[Patch v2 0/3] Refactor and clean up codes of mst

[Patch v2 0/3] Refactor and clean up codes of mst

[Wayne Lin]

This patch set is mainly trying to organize the mst code today a bit.
Like to clarify and organize the sequence of mst payload allocation and
removement.And also clean up some redundant codes today.

The main refactor one is the patch
"drm/mst: Refactor the flow for payload allocation/removement"
which is adding a new enum variable in stuct drm_dp_mst_atomic_payload
to represent the status of paylad alloction, and then handle the payload
accordingly. Besides, rename some drm mst functions to better express the
behind idea.

The other two patches are mainly to clean up unnecessary codes.

Changes since v1:
* Remove the set but not use variable 'old_payload' in function
  'nv50_msto_prepare'. Catched by kernel test robot <lkp@intel.com>

Wayne Lin (3):
  drm/mst: delete unnecessary case in drm_dp_add_payload_part2()
  drm/mst: Refactor the flow for payload allocation/removement
  drm/mst: adjust the function drm_dp_remove_payload_part2()

 .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  60 +-----
 drivers/gpu/drm/display/drm_dp_mst_topology.c | 189 +++++++++++-------
 drivers/gpu/drm/i915/display/intel_dp_mst.c   |  13 +-
 drivers/gpu/drm/nouveau/dispnv50/disp.c       |  17 +-
 include/drm/display/drm_dp_mst_helper.h       |  22 +-
 5 files changed, 159 insertions(+), 142 deletions(-)

-- 
2.37.3

[Patch v2 1/3] drm/mst: delete unnecessary case in drm_dp_add_payload_part2()

[Wayne Lin]

[Why]
There is no need to consider payload->delete case since we won't call
drm_dp_add_payload_part2() to create a payload when we're about to
remove it.

[How]
Delete unnecessary case to simplify the code.

Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
---
 drivers/gpu/drm/display/drm_dp_mst_topology.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index ed96cfcfa304..4d80426757ab 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -3411,12 +3411,8 @@ int drm_dp_add_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
 
 	ret = drm_dp_create_payload_step2(mgr, payload);
 	if (ret < 0) {
-		if (!payload->delete)
-			drm_err(mgr->dev, "Step 2 of creating MST payload for %p failed: %d\n",
-				payload->port, ret);
-		else
-			drm_dbg_kms(mgr->dev, "Step 2 of removing MST payload for %p failed: %d\n",
-				    payload->port, ret);
+		drm_err(mgr->dev, "Step 2 of creating MST payload for %p failed: %d\n",
+			payload->port, ret);
 	}
 
 	return ret;
-- 
2.37.3

[Patch v2 2/3] drm/mst: Refactor the flow for payload allocation/removement

[Wayne Lin]

[Why]
Today, the allocation/deallocation steps and status is a bit unclear.

For instance, payload->vc_start_slot = -1 stands for "the failure of
updating DPCD payload ID table" and can also represent as "payload is not
allocated yet". These two cases should be handled differently and hence
better to distinguish them for better understanding.

[How]
Define enumeration - ALLOCATION_LOCAL, ALLOCATION_DFP and ALLOCATION_REMOTE
to distinguish different allocation status. Adjust the code to handle
different status accordingly for better understanding the sequence of
payload allocation and payload removement.

For payload creation, the procedure should look like this:
DRM part 1:
* step 1 - update sw mst mgr variables to add a new payload
* step 2 - add payload at immediate DFP DPCD payload table

Driver:
* Add new payload in HW and sync up with DFP by sending ACT

DRM Part 2:
* Send ALLOCATE_PAYLOAD sideband message to allocate bandwidth along the
  virtual channel.

And as for payload removement, the procedure should look like this:
DRM part 1:
* step 1 - Send ALLOCATE_PAYLOAD sideband message to release bandwidth
           along the virtual channel
* step 2 - Clear payload allocation at immediate DFP DPCD payload table

Driver:
* Remove the payload in HW and sync up with DFP by sending ACT

DRM part 2:
* update sw mst mgr variables to remove the payload

Note that it's fine to fail when communicate with the branch device
connected at immediate downstrean-facing port, but updating variables of
SW mst mgr and HW configuration should be conducted anyway. That's because
it's under commit_tail and we need to complete the HW programming.

Changes since v1:
* Remove the set but not use variable 'old_payload' in function
  'nv50_msto_prepare'. Catched by kernel test robot <lkp@intel.com>

Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
---
 .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  20 ++-
 drivers/gpu/drm/display/drm_dp_mst_topology.c | 159 +++++++++++-------
 drivers/gpu/drm/i915/display/intel_dp_mst.c   |  18 +-
 drivers/gpu/drm/nouveau/dispnv50/disp.c       |  21 +--
 include/drm/display/drm_dp_mst_helper.h       |  23 ++-
 5 files changed, 153 insertions(+), 88 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
index d9a482908380..9ad509279b0a 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
@@ -219,7 +219,7 @@ static void dm_helpers_construct_old_payload(
 	/* Set correct time_slots/PBN of old payload.
 	 * other fields (delete & dsc_enabled) in
 	 * struct drm_dp_mst_atomic_payload are don't care fields
-	 * while calling drm_dp_remove_payload()
+	 * while calling drm_dp_remove_payload_part2()
 	 */
 	for (i = 0; i < current_link_table.stream_count; i++) {
 		dc_alloc =
@@ -262,13 +262,12 @@ bool dm_helpers_dp_mst_write_payload_allocation_table(
 
 	mst_mgr = &aconnector->mst_root->mst_mgr;
 	mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
-
-	/* It's OK for this to fail */
 	new_payload = drm_atomic_get_mst_payload_state(mst_state, aconnector->mst_output_port);
 
 	if (enable) {
 		target_payload = new_payload;
 
+		/* It's OK for this to fail */
 		drm_dp_add_payload_part1(mst_mgr, mst_state, new_payload);
 	} else {
 		/* construct old payload by VCPI*/
@@ -276,7 +275,7 @@ bool dm_helpers_dp_mst_write_payload_allocation_table(
 						new_payload, &old_payload);
 		target_payload = &old_payload;
 
-		drm_dp_remove_payload(mst_mgr, mst_state, &old_payload, new_payload);
+		drm_dp_remove_payload_part1(mst_mgr, mst_state, new_payload);
 	}
 
 	/* mst_mgr->->payloads are VC payload notify MST branch using DPCD or
@@ -342,7 +341,7 @@ bool dm_helpers_dp_mst_send_payload_allocation(
 	struct amdgpu_dm_connector *aconnector;
 	struct drm_dp_mst_topology_state *mst_state;
 	struct drm_dp_mst_topology_mgr *mst_mgr;
-	struct drm_dp_mst_atomic_payload *payload;
+	struct drm_dp_mst_atomic_payload *new_payload, *old_payload;
 	enum mst_progress_status set_flag = MST_ALLOCATE_NEW_PAYLOAD;
 	enum mst_progress_status clr_flag = MST_CLEAR_ALLOCATED_PAYLOAD;
 	int ret = 0;
@@ -355,15 +354,20 @@ bool dm_helpers_dp_mst_send_payload_allocation(
 	mst_mgr = &aconnector->mst_root->mst_mgr;
 	mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
 
-	payload = drm_atomic_get_mst_payload_state(mst_state, aconnector->mst_output_port);
+	new_payload = drm_atomic_get_mst_payload_state(mst_state, aconnector->mst_output_port);
 
 	if (!enable) {
 		set_flag = MST_CLEAR_ALLOCATED_PAYLOAD;
 		clr_flag = MST_ALLOCATE_NEW_PAYLOAD;
 	}
 
-	if (enable)
-		ret = drm_dp_add_payload_part2(mst_mgr, mst_state->base.state, payload);
+	if (enable) {
+		ret = drm_dp_add_payload_part2(mst_mgr, mst_state->base.state, new_payload);
+	} else {
+		dm_helpers_construct_old_payload(stream->link, mst_state->pbn_div,
+						 new_payload, old_payload);
+		drm_dp_remove_payload_part2(mst_mgr, mst_state, old_payload, new_payload);
+	}
 
 	if (ret) {
 		amdgpu_dm_set_mst_status(&aconnector->mst_status,
diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index 4d80426757ab..e04f87ff755a 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -3255,15 +3255,15 @@ int drm_dp_send_query_stream_enc_status(struct drm_dp_mst_topology_mgr *mgr,
 }
 EXPORT_SYMBOL(drm_dp_send_query_stream_enc_status);
 
-static int drm_dp_create_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
-				       struct drm_dp_mst_atomic_payload *payload)
+static int drm_dp_create_payload_at_dfp(struct drm_dp_mst_topology_mgr *mgr,
+					struct drm_dp_mst_atomic_payload *payload)
 {
 	return drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload->vc_start_slot,
 					 payload->time_slots);
 }
 
-static int drm_dp_create_payload_step2(struct drm_dp_mst_topology_mgr *mgr,
-				       struct drm_dp_mst_atomic_payload *payload)
+static int drm_dp_create_payload_to_remote(struct drm_dp_mst_topology_mgr *mgr,
+					   struct drm_dp_mst_atomic_payload *payload)
 {
 	int ret;
 	struct drm_dp_mst_port *port = drm_dp_mst_topology_get_port_validated(mgr, payload->port);
@@ -3276,17 +3276,20 @@ static int drm_dp_create_payload_step2(struct drm_dp_mst_topology_mgr *mgr,
 	return ret;
 }
 
-static int drm_dp_destroy_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
-					struct drm_dp_mst_topology_state *mst_state,
-					struct drm_dp_mst_atomic_payload *payload)
+static void drm_dp_destroy_payload_at_remote_and_dfp(struct drm_dp_mst_topology_mgr *mgr,
+						     struct drm_dp_mst_topology_state *mst_state,
+						     struct drm_dp_mst_atomic_payload *payload)
 {
 	drm_dbg_kms(mgr->dev, "\n");
 
 	/* it's okay for these to fail */
-	drm_dp_payload_send_msg(mgr, payload->port, payload->vcpi, 0);
-	drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload->vc_start_slot, 0);
+	if (payload->payload_allocation_status == DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE) {
+		drm_dp_payload_send_msg(mgr, payload->port, payload->vcpi, 0);
+		payload->payload_allocation_status = DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
+	}
 
-	return 0;
+	if (payload->payload_allocation_status == DRM_DP_MST_PAYLOAD_ALLOCATION_DFP)
+		drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload->vc_start_slot, 0);
 }
 
 /**
@@ -3296,81 +3299,105 @@ static int drm_dp_destroy_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
  * @payload: The payload to write
  *
  * Determines the starting time slot for the given payload, and programs the VCPI for this payload
- * into hardware. After calling this, the driver should generate ACT and payload packets.
+ * into the DPCD of DPRX. After calling this, the driver should generate ACT and payload packets.
  *
- * Returns: 0 on success, error code on failure. In the event that this fails,
- * @payload.vc_start_slot will also be set to -1.
+ * Returns: 0 on success, error code on failure.
  */
 int drm_dp_add_payload_part1(struct drm_dp_mst_topology_mgr *mgr,
 			     struct drm_dp_mst_topology_state *mst_state,
 			     struct drm_dp_mst_atomic_payload *payload)
 {
 	struct drm_dp_mst_port *port;
-	int ret;
+	int ret = 0;
+	bool allocate = true;
+
+	/* Update mst mgr info */
+	if (mgr->payload_count == 0)
+		mgr->next_start_slot = mst_state->start_slot;
+
+	payload->vc_start_slot = mgr->next_start_slot;
+
+	mgr->payload_count++;
+	mgr->next_start_slot += payload->time_slots;
 
+	/* Allocate payload to immediate downstream facing port */
 	port = drm_dp_mst_topology_get_port_validated(mgr, payload->port);
 	if (!port) {
 		drm_dbg_kms(mgr->dev,
-			    "VCPI %d for port %p not in topology, not creating a payload\n",
+			    "VCPI %d for port %p not in topology, not creating a payload to remote\n",
 			    payload->vcpi, payload->port);
-		payload->vc_start_slot = -1;
-		return 0;
+		allocate = false;
 	}
 
-	if (mgr->payload_count == 0)
-		mgr->next_start_slot = mst_state->start_slot;
-
-	payload->vc_start_slot = mgr->next_start_slot;
+	if (allocate) {
+		ret = drm_dp_create_payload_at_dfp(mgr, payload);
+		if (ret < 0)
+			drm_warn(mgr->dev, "Failed to create MST payload for port %p: %d\n",
+				 payload->port, ret);
 
-	ret = drm_dp_create_payload_step1(mgr, payload);
-	drm_dp_mst_topology_put_port(port);
-	if (ret < 0) {
-		drm_warn(mgr->dev, "Failed to create MST payload for port %p: %d\n",
-			 payload->port, ret);
-		payload->vc_start_slot = -1;
-		return ret;
 	}
 
-	mgr->payload_count++;
-	mgr->next_start_slot += payload->time_slots;
+	payload->payload_allocation_status =
+		(!allocate || ret < 0) ? DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL :
+								DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
 
-	return 0;
+	drm_dp_mst_topology_put_port(port);
+
+	return ret;
 }
 EXPORT_SYMBOL(drm_dp_add_payload_part1);
 
 /**
- * drm_dp_remove_payload() - Remove an MST payload
+ * drm_dp_remove_payload_part1() - Remove an MST payload along the virtual channel
  * @mgr: Manager to use.
  * @mst_state: The MST atomic state
- * @old_payload: The payload with its old state
- * @new_payload: The payload to write
+ * @payload: The payload to remove
  *
- * Removes a payload from an MST topology if it was successfully assigned a start slot. Also updates
- * the starting time slots of all other payloads which would have been shifted towards the start of
- * the VC table as a result. After calling this, the driver should generate ACT and payload packets.
+ * Removes a payload along the virtual channel if it was successfully allocated.
+ * After calling this, the driver should set HW to generate ACT and then switch to new
+ * payload allocation state.
  */
-void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
-			   struct drm_dp_mst_topology_state *mst_state,
-			   const struct drm_dp_mst_atomic_payload *old_payload,
-			   struct drm_dp_mst_atomic_payload *new_payload)
+void drm_dp_remove_payload_part1(struct drm_dp_mst_topology_mgr *mgr,
+				 struct drm_dp_mst_topology_state *mst_state,
+				 struct drm_dp_mst_atomic_payload *payload)
 {
-	struct drm_dp_mst_atomic_payload *pos;
+	/* Remove remote payload allocation */
 	bool send_remove = false;
 
-	/* We failed to make the payload, so nothing to do */
-	if (new_payload->vc_start_slot == -1)
-		return;
-
 	mutex_lock(&mgr->lock);
-	send_remove = drm_dp_mst_port_downstream_of_branch(new_payload->port, mgr->mst_primary);
+	send_remove = drm_dp_mst_port_downstream_of_branch(payload->port, mgr->mst_primary);
 	mutex_unlock(&mgr->lock);
 
 	if (send_remove)
-		drm_dp_destroy_payload_step1(mgr, mst_state, new_payload);
+		drm_dp_destroy_payload_at_remote_and_dfp(mgr, mst_state, payload);
 	else
 		drm_dbg_kms(mgr->dev, "Payload for VCPI %d not in topology, not sending remove\n",
-			    new_payload->vcpi);
+			    payload->vcpi);
+
+	payload->payload_allocation_status = DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL;
+}
+EXPORT_SYMBOL(drm_dp_remove_payload_part1);
 
+/**
+ * drm_dp_remove_payload_part2() - Remove an MST payload locally
+ * @mgr: Manager to use.
+ * @mst_state: The MST atomic state
+ * @old_payload: The payload with its old state
+ * @new_payload: The payload with its latest state
+ *
+ * Updates the starting time slots of all other payloads which would have been shifted towards
+ * the start of the payload ID table as a result of removing a payload. Driver should call this
+ * function whenever it removes a payload in its HW. It's independent to the result of payload
+ * allocation/deallocation at branch devices along the virtual channel.
+ */
+void drm_dp_remove_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
+				 struct drm_dp_mst_topology_state *mst_state,
+				 const struct drm_dp_mst_atomic_payload *old_payload,
+				 struct drm_dp_mst_atomic_payload *new_payload)
+{
+	struct drm_dp_mst_atomic_payload *pos;
+
+	/* Remove local payload allocation */
 	list_for_each_entry(pos, &mst_state->payloads, next) {
 		if (pos != new_payload && pos->vc_start_slot > new_payload->vc_start_slot)
 			pos->vc_start_slot -= old_payload->time_slots;
@@ -3382,9 +3409,10 @@ void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
 
 	if (new_payload->delete)
 		drm_dp_mst_put_port_malloc(new_payload->port);
-}
-EXPORT_SYMBOL(drm_dp_remove_payload);
 
+	new_payload->payload_allocation_status = DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
+}
+EXPORT_SYMBOL(drm_dp_remove_payload_part2);
 /**
  * drm_dp_add_payload_part2() - Execute payload update part 2
  * @mgr: Manager to use.
@@ -3403,17 +3431,19 @@ int drm_dp_add_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
 	int ret = 0;
 
 	/* Skip failed payloads */
-	if (payload->vc_start_slot == -1) {
-		drm_dbg_kms(mgr->dev, "Part 1 of payload creation for %s failed, skipping part 2\n",
+	if (payload->payload_allocation_status != DRM_DP_MST_PAYLOAD_ALLOCATION_DFP) {
+		drm_dbg_kms(state->dev, "Part 1 of payload creation for %s failed, skipping part 2\n",
 			    payload->port->connector->name);
 		return -EIO;
 	}
 
-	ret = drm_dp_create_payload_step2(mgr, payload);
-	if (ret < 0) {
+	/* Allocate payload to remote end */
+	ret = drm_dp_create_payload_to_remote(mgr, payload);
+	if (ret < 0)
 		drm_err(mgr->dev, "Step 2 of creating MST payload for %p failed: %d\n",
 			payload->port, ret);
-	}
+	else
+		payload->payload_allocation_status = DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE;
 
 	return ret;
 }
@@ -4324,6 +4354,7 @@ int drm_dp_atomic_find_time_slots(struct drm_atomic_state *state,
 		drm_dp_mst_get_port_malloc(port);
 		payload->port = port;
 		payload->vc_start_slot = -1;
+		payload->payload_allocation_status = DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
 		list_add(&payload->next, &topology_state->payloads);
 	}
 	payload->time_slots = req_slots;
@@ -4493,7 +4524,7 @@ void drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state *state)
 		}
 
 		/* Now that previous state is committed, it's safe to copy over the start slot
-		 * assignments
+		 * and allocation status assignments
 		 */
 		list_for_each_entry(old_payload, &old_mst_state->payloads, next) {
 			if (old_payload->delete)
@@ -4502,6 +4533,8 @@ void drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state *state)
 			new_payload = drm_atomic_get_mst_payload_state(new_mst_state,
 								       old_payload->port);
 			new_payload->vc_start_slot = old_payload->vc_start_slot;
+			new_payload->payload_allocation_status =
+							old_payload->payload_allocation_status;
 		}
 	}
 }
@@ -4818,6 +4851,13 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
 	struct drm_dp_mst_atomic_payload *payload;
 	int i, ret;
 
+	static const char *const status[] = {
+		"None",
+		"Local",
+		"DFP",
+		"Remote",
+	};
+
 	mutex_lock(&mgr->lock);
 	if (mgr->mst_primary)
 		drm_dp_mst_dump_mstb(m, mgr->mst_primary);
@@ -4834,7 +4874,7 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
 	seq_printf(m, "payload_mask: %x, max_payloads: %d, start_slot: %u, pbn_div: %d\n",
 		   state->payload_mask, mgr->max_payloads, state->start_slot, state->pbn_div);
 
-	seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc |     sink name     |\n");
+	seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc | status |     sink name     |\n");
 	for (i = 0; i < mgr->max_payloads; i++) {
 		list_for_each_entry(payload, &state->payloads, next) {
 			char name[14];
@@ -4843,7 +4883,7 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
 				continue;
 
 			fetch_monitor_name(mgr, payload->port, name, sizeof(name));
-			seq_printf(m, " %5d %6d %6d %02d - %02d %5d %5s %19s\n",
+			seq_printf(m, " %5d %6d %6d %02d - %02d %5d %5s %8s %19s\n",
 				   i,
 				   payload->port->port_num,
 				   payload->vcpi,
@@ -4851,6 +4891,7 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
 				   payload->vc_start_slot + payload->time_slots - 1,
 				   payload->pbn,
 				   payload->dsc_enabled ? "Y" : "N",
+				   status[payload->payload_allocation_status],
 				   (*name != 0) ? name : "Unknown");
 		}
 	}
diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index e3f176a093d2..5f73cdabe7a1 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -557,12 +557,8 @@ static void intel_mst_disable_dp(struct intel_atomic_state *state,
 	struct intel_dp *intel_dp = &dig_port->dp;
 	struct intel_connector *connector =
 		to_intel_connector(old_conn_state->connector);
-	struct drm_dp_mst_topology_state *old_mst_state =
-		drm_atomic_get_old_mst_topology_state(&state->base, &intel_dp->mst_mgr);
 	struct drm_dp_mst_topology_state *new_mst_state =
 		drm_atomic_get_new_mst_topology_state(&state->base, &intel_dp->mst_mgr);
-	const struct drm_dp_mst_atomic_payload *old_payload =
-		drm_atomic_get_mst_payload_state(old_mst_state, connector->port);
 	struct drm_dp_mst_atomic_payload *new_payload =
 		drm_atomic_get_mst_payload_state(new_mst_state, connector->port);
 	struct drm_i915_private *i915 = to_i915(connector->base.dev);
@@ -572,8 +568,7 @@ static void intel_mst_disable_dp(struct intel_atomic_state *state,
 
 	intel_hdcp_disable(intel_mst->connector);
 
-	drm_dp_remove_payload(&intel_dp->mst_mgr, new_mst_state,
-			      old_payload, new_payload);
+	drm_dp_remove_payload_part1(&intel_dp->mst_mgr, new_mst_state, new_payload);
 
 	intel_audio_codec_disable(encoder, old_crtc_state, old_conn_state);
 }
@@ -588,6 +583,14 @@ static void intel_mst_post_disable_dp(struct intel_atomic_state *state,
 	struct intel_dp *intel_dp = &dig_port->dp;
 	struct intel_connector *connector =
 		to_intel_connector(old_conn_state->connector);
+	struct drm_dp_mst_topology_state *old_mst_state =
+		drm_atomic_get_old_mst_topology_state(&state->base, &intel_dp->mst_mgr);
+	struct drm_dp_mst_topology_state *new_mst_state =
+		drm_atomic_get_new_mst_topology_state(&state->base, &intel_dp->mst_mgr);
+	const struct drm_dp_mst_atomic_payload *old_payload =
+		drm_atomic_get_mst_payload_state(old_mst_state, connector->port);
+	struct drm_dp_mst_atomic_payload *new_payload =
+		drm_atomic_get_mst_payload_state(new_mst_state, connector->port);
 	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
 	bool last_mst_stream;
 
@@ -608,6 +611,9 @@ static void intel_mst_post_disable_dp(struct intel_atomic_state *state,
 
 	wait_for_act_sent(encoder, old_crtc_state);
 
+	drm_dp_remove_payload_part2(&intel_dp->mst_mgr, new_mst_state,
+				    old_payload, new_payload);
+
 	intel_ddi_disable_transcoder_func(old_crtc_state);
 
 	if (DISPLAY_VER(dev_priv) >= 9)
diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index 4e7c9c353c51..bba01fa0780c 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -882,21 +882,26 @@ struct nouveau_encoder *nv50_real_outp(struct drm_encoder *encoder)
 
 static void
 nv50_msto_cleanup(struct drm_atomic_state *state,
-		  struct drm_dp_mst_topology_state *mst_state,
+		  struct drm_dp_mst_topology_state *new_mst_state,
 		  struct drm_dp_mst_topology_mgr *mgr,
 		  struct nv50_msto *msto)
 {
 	struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
-	struct drm_dp_mst_atomic_payload *payload =
-		drm_atomic_get_mst_payload_state(mst_state, msto->mstc->port);
+	struct drm_dp_mst_atomic_payload *new_payload =
+		drm_atomic_get_mst_payload_state(new_mst_state, msto->mstc->port);
+	struct drm_dp_mst_topology_state *old_mst_state =
+		drm_atomic_get_old_mst_topology_state(state, mgr);
+	const struct drm_dp_mst_atomic_payload *old_payload =
+		drm_atomic_get_mst_payload_state(old_mst_state, msto->mstc->port);
 
 	NV_ATOMIC(drm, "%s: msto cleanup\n", msto->encoder.name);
 
 	if (msto->disabled) {
 		msto->mstc = NULL;
 		msto->disabled = false;
+		drm_dp_remove_payload_part2(mgr, new_mst_state, old_payload, new_payload);
 	} else if (msto->enabled) {
-		drm_dp_add_payload_part2(mgr, state, payload);
+		drm_dp_add_payload_part2(mgr, state, new_payload);
 		msto->enabled = false;
 	}
 }
@@ -910,19 +915,15 @@ nv50_msto_prepare(struct drm_atomic_state *state,
 	struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
 	struct nv50_mstc *mstc = msto->mstc;
 	struct nv50_mstm *mstm = mstc->mstm;
-	struct drm_dp_mst_topology_state *old_mst_state;
-	struct drm_dp_mst_atomic_payload *payload, *old_payload;
+	struct drm_dp_mst_atomic_payload *payload;
 
 	NV_ATOMIC(drm, "%s: msto prepare\n", msto->encoder.name);
 
-	old_mst_state = drm_atomic_get_old_mst_topology_state(state, mgr);
-
 	payload = drm_atomic_get_mst_payload_state(mst_state, mstc->port);
-	old_payload = drm_atomic_get_mst_payload_state(old_mst_state, mstc->port);
 
 	// TODO: Figure out if we want to do a better job of handling VCPI allocation failures here?
 	if (msto->disabled) {
-		drm_dp_remove_payload(mgr, mst_state, old_payload, payload);
+		drm_dp_remove_payload_part1(mgr, mst_state, payload);
 
 		nvif_outp_dp_mst_vcpi(&mstm->outp->outp, msto->head->base.index, 0, 0, 0, 0);
 	} else {
diff --git a/include/drm/display/drm_dp_mst_helper.h b/include/drm/display/drm_dp_mst_helper.h
index ed5c9660563c..4429d3b1745b 100644
--- a/include/drm/display/drm_dp_mst_helper.h
+++ b/include/drm/display/drm_dp_mst_helper.h
@@ -46,6 +46,13 @@ struct drm_dp_mst_topology_ref_history {
 };
 #endif /* IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) */
 
+enum drm_dp_mst_payload_allocation {
+	DRM_DP_MST_PAYLOAD_ALLOCATION_NONE,
+	DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL,
+	DRM_DP_MST_PAYLOAD_ALLOCATION_DFP,
+	DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE,
+};
+
 struct drm_dp_mst_branch;
 
 /**
@@ -537,7 +544,7 @@ struct drm_dp_mst_atomic_payload {
 	 *   drm_dp_mst_atomic_wait_for_dependencies() has been called, which will ensure the
 	 *   previous MST states payload start slots have been copied over to the new state. Note
 	 *   that a new start slot won't be assigned/removed from this payload until
-	 *   drm_dp_add_payload_part1()/drm_dp_remove_payload() have been called.
+	 *   drm_dp_add_payload_part1()/drm_dp_remove_payload_part2() have been called.
 	 * * Acquire the MST modesetting lock, and then wait for any pending MST-related commits to
 	 *   get committed to hardware by calling drm_crtc_commit_wait() on each of the
 	 *   &drm_crtc_commit structs in &drm_dp_mst_topology_state.commit_deps.
@@ -564,6 +571,9 @@ struct drm_dp_mst_atomic_payload {
 	/** @dsc_enabled: Whether or not this payload has DSC enabled */
 	bool dsc_enabled : 1;
 
+	/** @payload_allocation_status: The allocation status of this payload */
+	enum drm_dp_mst_payload_allocation payload_allocation_status;
+
 	/** @next: The list node for this payload */
 	struct list_head next;
 };
@@ -842,10 +852,13 @@ int drm_dp_add_payload_part1(struct drm_dp_mst_topology_mgr *mgr,
 int drm_dp_add_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
 			     struct drm_atomic_state *state,
 			     struct drm_dp_mst_atomic_payload *payload);
-void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
-			   struct drm_dp_mst_topology_state *mst_state,
-			   const struct drm_dp_mst_atomic_payload *old_payload,
-			   struct drm_dp_mst_atomic_payload *new_payload);
+void drm_dp_remove_payload_part1(struct drm_dp_mst_topology_mgr *mgr,
+				 struct drm_dp_mst_topology_state *mst_state,
+				 struct drm_dp_mst_atomic_payload *payload);
+void drm_dp_remove_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
+				 struct drm_dp_mst_topology_state *mst_state,
+				 const struct drm_dp_mst_atomic_payload *old_payload,
+				 struct drm_dp_mst_atomic_payload *new_payload);
 
 int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr);
 
-- 
2.37.3

[Patch v2 3/3] drm/mst: adjust the function drm_dp_remove_payload_part2()

[Wayne Lin]

[Why]
Now in drm_dp_remove_payload_part2(), it utilizes the time slot number
of the payload in old state to represent the one in the payload table
at the moment.

It would be better to clarify the idea by using the latest allocated
time slot number for the port at the moment instead and which info is
already included in new mst_state. By this, we can also remove redundant
workaround for amdgpu driver.

[How]
Remove "old_payload" input of drm_dp_remove_payload_part2() and get the
latest number of allocated time slot for the port from new mst_state
instead.

Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
---
 .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c | 70 ++++---------------
 drivers/gpu/drm/display/drm_dp_mst_topology.c | 32 ++++++---
 drivers/gpu/drm/i915/display/intel_dp_mst.c   |  7 +-
 drivers/gpu/drm/nouveau/dispnv50/disp.c       |  6 +-
 include/drm/display/drm_dp_mst_helper.h       |  9 ++-
 5 files changed, 40 insertions(+), 84 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
index 9ad509279b0a..e852da686c26 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
@@ -203,40 +203,6 @@ void dm_helpers_dp_update_branch_info(
 	const struct dc_link *link)
 {}
 
-static void dm_helpers_construct_old_payload(
-			struct dc_link *link,
-			int pbn_per_slot,
-			struct drm_dp_mst_atomic_payload *new_payload,
-			struct drm_dp_mst_atomic_payload *old_payload)
-{
-	struct link_mst_stream_allocation_table current_link_table =
-									link->mst_stream_alloc_table;
-	struct link_mst_stream_allocation *dc_alloc;
-	int i;
-
-	*old_payload = *new_payload;
-
-	/* Set correct time_slots/PBN of old payload.
-	 * other fields (delete & dsc_enabled) in
-	 * struct drm_dp_mst_atomic_payload are don't care fields
-	 * while calling drm_dp_remove_payload_part2()
-	 */
-	for (i = 0; i < current_link_table.stream_count; i++) {
-		dc_alloc =
-			&current_link_table.stream_allocations[i];
-
-		if (dc_alloc->vcp_id == new_payload->vcpi) {
-			old_payload->time_slots = dc_alloc->slot_count;
-			old_payload->pbn = dc_alloc->slot_count * pbn_per_slot;
-			break;
-		}
-	}
-
-	/* make sure there is an old payload*/
-	ASSERT(i != current_link_table.stream_count);
-
-}
-
 /*
  * Writes payload allocation table in immediate downstream device.
  */
@@ -248,7 +214,7 @@ bool dm_helpers_dp_mst_write_payload_allocation_table(
 {
 	struct amdgpu_dm_connector *aconnector;
 	struct drm_dp_mst_topology_state *mst_state;
-	struct drm_dp_mst_atomic_payload *target_payload, *new_payload, old_payload;
+	struct drm_dp_mst_atomic_payload *payload;
 	struct drm_dp_mst_topology_mgr *mst_mgr;
 
 	aconnector = (struct amdgpu_dm_connector *)stream->dm_stream_context;
@@ -262,27 +228,20 @@ bool dm_helpers_dp_mst_write_payload_allocation_table(
 
 	mst_mgr = &aconnector->mst_root->mst_mgr;
 	mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
-	new_payload = drm_atomic_get_mst_payload_state(mst_state, aconnector->mst_output_port);
-
-	if (enable) {
-		target_payload = new_payload;
+	payload = drm_atomic_get_mst_payload_state(mst_state, aconnector->mst_output_port);
 
+	if (enable)
 		/* It's OK for this to fail */
-		drm_dp_add_payload_part1(mst_mgr, mst_state, new_payload);
-	} else {
-		/* construct old payload by VCPI*/
-		dm_helpers_construct_old_payload(stream->link, mst_state->pbn_div,
-						new_payload, &old_payload);
-		target_payload = &old_payload;
+		drm_dp_add_payload_part1(mst_mgr, mst_state, payload);
+	else
 
-		drm_dp_remove_payload_part1(mst_mgr, mst_state, new_payload);
-	}
+		drm_dp_remove_payload_part1(mst_mgr, mst_state, payload);
 
 	/* mst_mgr->->payloads are VC payload notify MST branch using DPCD or
 	 * AUX message. The sequence is slot 1-63 allocated sequence for each
 	 * stream. AMD ASIC stream slot allocation should follow the same
 	 * sequence. copy DRM MST allocation to dc */
-	fill_dc_mst_payload_table_from_drm(stream->link, enable, target_payload, proposed_table);
+	fill_dc_mst_payload_table_from_drm(stream->link, enable, payload, proposed_table);
 
 	return true;
 }
@@ -341,7 +300,7 @@ bool dm_helpers_dp_mst_send_payload_allocation(
 	struct amdgpu_dm_connector *aconnector;
 	struct drm_dp_mst_topology_state *mst_state;
 	struct drm_dp_mst_topology_mgr *mst_mgr;
-	struct drm_dp_mst_atomic_payload *new_payload, *old_payload;
+	struct drm_dp_mst_atomic_payload *payload;
 	enum mst_progress_status set_flag = MST_ALLOCATE_NEW_PAYLOAD;
 	enum mst_progress_status clr_flag = MST_CLEAR_ALLOCATED_PAYLOAD;
 	int ret = 0;
@@ -354,20 +313,17 @@ bool dm_helpers_dp_mst_send_payload_allocation(
 	mst_mgr = &aconnector->mst_root->mst_mgr;
 	mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
 
-	new_payload = drm_atomic_get_mst_payload_state(mst_state, aconnector->mst_output_port);
+	payload = drm_atomic_get_mst_payload_state(mst_state, aconnector->mst_output_port);
 
 	if (!enable) {
 		set_flag = MST_CLEAR_ALLOCATED_PAYLOAD;
 		clr_flag = MST_ALLOCATE_NEW_PAYLOAD;
 	}
 
-	if (enable) {
-		ret = drm_dp_add_payload_part2(mst_mgr, mst_state->base.state, new_payload);
-	} else {
-		dm_helpers_construct_old_payload(stream->link, mst_state->pbn_div,
-						 new_payload, old_payload);
-		drm_dp_remove_payload_part2(mst_mgr, mst_state, old_payload, new_payload);
-	}
+	if (enable)
+		ret = drm_dp_add_payload_part2(mst_mgr, mst_state->base.state, payload);
+	else
+		drm_dp_remove_payload_part2(mst_mgr, mst_state, payload);
 
 	if (ret) {
 		amdgpu_dm_set_mst_status(&aconnector->mst_status,
diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index e04f87ff755a..4270178f95f6 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -3382,8 +3382,7 @@ EXPORT_SYMBOL(drm_dp_remove_payload_part1);
  * drm_dp_remove_payload_part2() - Remove an MST payload locally
  * @mgr: Manager to use.
  * @mst_state: The MST atomic state
- * @old_payload: The payload with its old state
- * @new_payload: The payload with its latest state
+ * @payload: The payload with its latest state
  *
  * Updates the starting time slots of all other payloads which would have been shifted towards
  * the start of the payload ID table as a result of removing a payload. Driver should call this
@@ -3392,25 +3391,36 @@ EXPORT_SYMBOL(drm_dp_remove_payload_part1);
  */
 void drm_dp_remove_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
 				 struct drm_dp_mst_topology_state *mst_state,
-				 const struct drm_dp_mst_atomic_payload *old_payload,
-				 struct drm_dp_mst_atomic_payload *new_payload)
+				 struct drm_dp_mst_atomic_payload *payload)
 {
 	struct drm_dp_mst_atomic_payload *pos;
+	u8 time_slots_to_remove;
+	u8 next_payload_vc_start = mgr->next_start_slot;
+
+	/* Find the current allocated time slot number of the payload */
+	list_for_each_entry(pos, &mst_state->payloads, next) {
+		if (pos != payload &&
+		    pos->vc_start_slot > payload->vc_start_slot &&
+		    pos->vc_start_slot < next_payload_vc_start)
+			next_payload_vc_start = pos->vc_start_slot;
+	}
+
+	time_slots_to_remove = next_payload_vc_start - payload->vc_start_slot;
 
 	/* Remove local payload allocation */
 	list_for_each_entry(pos, &mst_state->payloads, next) {
-		if (pos != new_payload && pos->vc_start_slot > new_payload->vc_start_slot)
-			pos->vc_start_slot -= old_payload->time_slots;
+		if (pos != payload && pos->vc_start_slot > payload->vc_start_slot)
+			pos->vc_start_slot -= time_slots_to_remove;
 	}
-	new_payload->vc_start_slot = -1;
+	payload->vc_start_slot = -1;
 
 	mgr->payload_count--;
-	mgr->next_start_slot -= old_payload->time_slots;
+	mgr->next_start_slot -= time_slots_to_remove;
 
-	if (new_payload->delete)
-		drm_dp_mst_put_port_malloc(new_payload->port);
+	if (payload->delete)
+		drm_dp_mst_put_port_malloc(payload->port);
 
-	new_payload->payload_allocation_status = DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
+	payload->payload_allocation_status = DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
 }
 EXPORT_SYMBOL(drm_dp_remove_payload_part2);
 /**
diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index 5f73cdabe7a1..91750c1dfc48 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -583,12 +583,8 @@ static void intel_mst_post_disable_dp(struct intel_atomic_state *state,
 	struct intel_dp *intel_dp = &dig_port->dp;
 	struct intel_connector *connector =
 		to_intel_connector(old_conn_state->connector);
-	struct drm_dp_mst_topology_state *old_mst_state =
-		drm_atomic_get_old_mst_topology_state(&state->base, &intel_dp->mst_mgr);
 	struct drm_dp_mst_topology_state *new_mst_state =
 		drm_atomic_get_new_mst_topology_state(&state->base, &intel_dp->mst_mgr);
-	const struct drm_dp_mst_atomic_payload *old_payload =
-		drm_atomic_get_mst_payload_state(old_mst_state, connector->port);
 	struct drm_dp_mst_atomic_payload *new_payload =
 		drm_atomic_get_mst_payload_state(new_mst_state, connector->port);
 	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
@@ -611,8 +607,7 @@ static void intel_mst_post_disable_dp(struct intel_atomic_state *state,
 
 	wait_for_act_sent(encoder, old_crtc_state);
 
-	drm_dp_remove_payload_part2(&intel_dp->mst_mgr, new_mst_state,
-				    old_payload, new_payload);
+	drm_dp_remove_payload_part2(&intel_dp->mst_mgr, new_mst_state, new_payload);
 
 	intel_ddi_disable_transcoder_func(old_crtc_state);
 
diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index bba01fa0780c..0d4286d0d872 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -889,17 +889,13 @@ nv50_msto_cleanup(struct drm_atomic_state *state,
 	struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
 	struct drm_dp_mst_atomic_payload *new_payload =
 		drm_atomic_get_mst_payload_state(new_mst_state, msto->mstc->port);
-	struct drm_dp_mst_topology_state *old_mst_state =
-		drm_atomic_get_old_mst_topology_state(state, mgr);
-	const struct drm_dp_mst_atomic_payload *old_payload =
-		drm_atomic_get_mst_payload_state(old_mst_state, msto->mstc->port);
 
 	NV_ATOMIC(drm, "%s: msto cleanup\n", msto->encoder.name);
 
 	if (msto->disabled) {
 		msto->mstc = NULL;
 		msto->disabled = false;
-		drm_dp_remove_payload_part2(mgr, new_mst_state, old_payload, new_payload);
+		drm_dp_remove_payload_part2(mgr, new_mst_state, new_payload);
 	} else if (msto->enabled) {
 		drm_dp_add_payload_part2(mgr, state, new_payload);
 		msto->enabled = false;
diff --git a/include/drm/display/drm_dp_mst_helper.h b/include/drm/display/drm_dp_mst_helper.h
index 4429d3b1745b..3f8ad28c77b1 100644
--- a/include/drm/display/drm_dp_mst_helper.h
+++ b/include/drm/display/drm_dp_mst_helper.h
@@ -853,12 +853,11 @@ int drm_dp_add_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
 			     struct drm_atomic_state *state,
 			     struct drm_dp_mst_atomic_payload *payload);
 void drm_dp_remove_payload_part1(struct drm_dp_mst_topology_mgr *mgr,
-				 struct drm_dp_mst_topology_state *mst_state,
-				 struct drm_dp_mst_atomic_payload *payload);
+				  struct drm_dp_mst_topology_state *mst_state,
+				  struct drm_dp_mst_atomic_payload *payload);
 void drm_dp_remove_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
-				 struct drm_dp_mst_topology_state *mst_state,
-				 const struct drm_dp_mst_atomic_payload *old_payload,
-				 struct drm_dp_mst_atomic_payload *new_payload);
+				  struct drm_dp_mst_topology_state *mst_state,
+				  struct drm_dp_mst_atomic_payload *payload);
 
 int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr);
 
-- 
2.37.3

Re: [Patch v2 2/3] drm/mst: Refactor the flow for payload allocation/removement

[Lyude Paul]

Oooooo! This is a wonderful idea so far - keeping track of the status of
allocations like this solves a lot of problems, especially with regards to the
fact this actually seems to make it possible for us to have much better
handling of payload failures in drivers - especially in situations like
suspend/resume. The naming changes here are awesome too.

I think this patch is good as far as I can tell review-wise! I haven't been
able to test it quite yet but I'll do it asap.

On Mon, 2023-08-07 at 10:56 +0800, Wayne Lin wrote:
> [Why]
> Today, the allocation/deallocation steps and status is a bit unclear.
> 
> For instance, payload->vc_start_slot = -1 stands for "the failure of
> updating DPCD payload ID table" and can also represent as "payload is not
> allocated yet". These two cases should be handled differently and hence
> better to distinguish them for better understanding.
> 
> [How]
> Define enumeration - ALLOCATION_LOCAL, ALLOCATION_DFP and ALLOCATION_REMOTE
> to distinguish different allocation status. Adjust the code to handle
> different status accordingly for better understanding the sequence of
> payload allocation and payload removement.
> 
> For payload creation, the procedure should look like this:
> DRM part 1:
> * step 1 - update sw mst mgr variables to add a new payload
> * step 2 - add payload at immediate DFP DPCD payload table
> 
> Driver:
> * Add new payload in HW and sync up with DFP by sending ACT
> 
> DRM Part 2:
> * Send ALLOCATE_PAYLOAD sideband message to allocate bandwidth along the
>   virtual channel.
> 
> And as for payload removement, the procedure should look like this:
> DRM part 1:
> * step 1 - Send ALLOCATE_PAYLOAD sideband message to release bandwidth
>            along the virtual channel
> * step 2 - Clear payload allocation at immediate DFP DPCD payload table
> 
> Driver:
> * Remove the payload in HW and sync up with DFP by sending ACT
> 
> DRM part 2:
> * update sw mst mgr variables to remove the payload
> 
> Note that it's fine to fail when communicate with the branch device
> connected at immediate downstrean-facing port, but updating variables of
> SW mst mgr and HW configuration should be conducted anyway. That's because
> it's under commit_tail and we need to complete the HW programming.

yay!

> 
> Changes since v1:
> * Remove the set but not use variable 'old_payload' in function
>   'nv50_msto_prepare'. Catched by kernel test robot <lkp@intel.com>
> 
> Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
> ---
>  .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  20 ++-
>  drivers/gpu/drm/display/drm_dp_mst_topology.c | 159 +++++++++++-------
>  drivers/gpu/drm/i915/display/intel_dp_mst.c   |  18 +-
>  drivers/gpu/drm/nouveau/dispnv50/disp.c       |  21 +--
>  include/drm/display/drm_dp_mst_helper.h       |  23 ++-
>  5 files changed, 153 insertions(+), 88 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> index d9a482908380..9ad509279b0a 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> @@ -219,7 +219,7 @@ static void dm_helpers_construct_old_payload(
>  	/* Set correct time_slots/PBN of old payload.
>  	 * other fields (delete & dsc_enabled) in
>  	 * struct drm_dp_mst_atomic_payload are don't care fields
> -	 * while calling drm_dp_remove_payload()
> +	 * while calling drm_dp_remove_payload_part2()
>  	 */
>  	for (i = 0; i < current_link_table.stream_count; i++) {
>  		dc_alloc =
> @@ -262,13 +262,12 @@ bool dm_helpers_dp_mst_write_payload_allocation_table(
>  
>  	mst_mgr = &aconnector->mst_root->mst_mgr;
>  	mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
> -
> -	/* It's OK for this to fail */
>  	new_payload = drm_atomic_get_mst_payload_state(mst_state, aconnector->mst_output_port);
>  
>  	if (enable) {
>  		target_payload = new_payload;
>  
> +		/* It's OK for this to fail */
>  		drm_dp_add_payload_part1(mst_mgr, mst_state, new_payload);
>  	} else {
>  		/* construct old payload by VCPI*/
> @@ -276,7 +275,7 @@ bool dm_helpers_dp_mst_write_payload_allocation_table(
>  						new_payload, &old_payload);
>  		target_payload = &old_payload;
>  
> -		drm_dp_remove_payload(mst_mgr, mst_state, &old_payload, new_payload);
> +		drm_dp_remove_payload_part1(mst_mgr, mst_state, new_payload);
>  	}
>  
>  	/* mst_mgr->->payloads are VC payload notify MST branch using DPCD or
> @@ -342,7 +341,7 @@ bool dm_helpers_dp_mst_send_payload_allocation(
>  	struct amdgpu_dm_connector *aconnector;
>  	struct drm_dp_mst_topology_state *mst_state;
>  	struct drm_dp_mst_topology_mgr *mst_mgr;
> -	struct drm_dp_mst_atomic_payload *payload;
> +	struct drm_dp_mst_atomic_payload *new_payload, *old_payload;
>  	enum mst_progress_status set_flag = MST_ALLOCATE_NEW_PAYLOAD;
>  	enum mst_progress_status clr_flag = MST_CLEAR_ALLOCATED_PAYLOAD;
>  	int ret = 0;
> @@ -355,15 +354,20 @@ bool dm_helpers_dp_mst_send_payload_allocation(
>  	mst_mgr = &aconnector->mst_root->mst_mgr;
>  	mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
>  
> -	payload = drm_atomic_get_mst_payload_state(mst_state, aconnector->mst_output_port);
> +	new_payload = drm_atomic_get_mst_payload_state(mst_state, aconnector->mst_output_port);
>  
>  	if (!enable) {
>  		set_flag = MST_CLEAR_ALLOCATED_PAYLOAD;
>  		clr_flag = MST_ALLOCATE_NEW_PAYLOAD;
>  	}
>  
> -	if (enable)
> -		ret = drm_dp_add_payload_part2(mst_mgr, mst_state->base.state, payload);
> +	if (enable) {
> +		ret = drm_dp_add_payload_part2(mst_mgr, mst_state->base.state, new_payload);
> +	} else {
> +		dm_helpers_construct_old_payload(stream->link, mst_state->pbn_div,
> +						 new_payload, old_payload);
> +		drm_dp_remove_payload_part2(mst_mgr, mst_state, old_payload, new_payload);
> +	}
>  
>  	if (ret) {
>  		amdgpu_dm_set_mst_status(&aconnector->mst_status,
> diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> index 4d80426757ab..e04f87ff755a 100644
> --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> @@ -3255,15 +3255,15 @@ int drm_dp_send_query_stream_enc_status(struct drm_dp_mst_topology_mgr *mgr,
>  }
>  EXPORT_SYMBOL(drm_dp_send_query_stream_enc_status);
>  
> -static int drm_dp_create_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
> -				       struct drm_dp_mst_atomic_payload *payload)
> +static int drm_dp_create_payload_at_dfp(struct drm_dp_mst_topology_mgr *mgr,
> +					struct drm_dp_mst_atomic_payload *payload)
>  {
>  	return drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload->vc_start_slot,
>  					 payload->time_slots);
>  }
>  
> -static int drm_dp_create_payload_step2(struct drm_dp_mst_topology_mgr *mgr,
> -				       struct drm_dp_mst_atomic_payload *payload)
> +static int drm_dp_create_payload_to_remote(struct drm_dp_mst_topology_mgr *mgr,
> +					   struct drm_dp_mst_atomic_payload *payload)
>  {
>  	int ret;
>  	struct drm_dp_mst_port *port = drm_dp_mst_topology_get_port_validated(mgr, payload->port);
> @@ -3276,17 +3276,20 @@ static int drm_dp_create_payload_step2(struct drm_dp_mst_topology_mgr *mgr,
>  	return ret;
>  }
>  
> -static int drm_dp_destroy_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
> -					struct drm_dp_mst_topology_state *mst_state,
> -					struct drm_dp_mst_atomic_payload *payload)
> +static void drm_dp_destroy_payload_at_remote_and_dfp(struct drm_dp_mst_topology_mgr *mgr,
> +						     struct drm_dp_mst_topology_state *mst_state,
> +						     struct drm_dp_mst_atomic_payload *payload)
>  {
>  	drm_dbg_kms(mgr->dev, "\n");
>  
>  	/* it's okay for these to fail */
> -	drm_dp_payload_send_msg(mgr, payload->port, payload->vcpi, 0);
> -	drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload->vc_start_slot, 0);
> +	if (payload->payload_allocation_status == DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE) {
> +		drm_dp_payload_send_msg(mgr, payload->port, payload->vcpi, 0);
> +		payload->payload_allocation_status = DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
> +	}
>  
> -	return 0;
> +	if (payload->payload_allocation_status == DRM_DP_MST_PAYLOAD_ALLOCATION_DFP)
> +		drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload->vc_start_slot, 0);
>  }
>  
>  /**
> @@ -3296,81 +3299,105 @@ static int drm_dp_destroy_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
>   * @payload: The payload to write
>   *
>   * Determines the starting time slot for the given payload, and programs the VCPI for this payload
> - * into hardware. After calling this, the driver should generate ACT and payload packets.
> + * into the DPCD of DPRX. After calling this, the driver should generate ACT and payload packets.
>   *
> - * Returns: 0 on success, error code on failure. In the event that this fails,
> - * @payload.vc_start_slot will also be set to -1.
> + * Returns: 0 on success, error code on failure.
>   */
>  int drm_dp_add_payload_part1(struct drm_dp_mst_topology_mgr *mgr,
>  			     struct drm_dp_mst_topology_state *mst_state,
>  			     struct drm_dp_mst_atomic_payload *payload)
>  {
>  	struct drm_dp_mst_port *port;
> -	int ret;
> +	int ret = 0;
> +	bool allocate = true;
> +
> +	/* Update mst mgr info */
> +	if (mgr->payload_count == 0)
> +		mgr->next_start_slot = mst_state->start_slot;
> +
> +	payload->vc_start_slot = mgr->next_start_slot;
> +
> +	mgr->payload_count++;
> +	mgr->next_start_slot += payload->time_slots;
>  
> +	/* Allocate payload to immediate downstream facing port */
>  	port = drm_dp_mst_topology_get_port_validated(mgr, payload->port);
>  	if (!port) {
>  		drm_dbg_kms(mgr->dev,
> -			    "VCPI %d for port %p not in topology, not creating a payload\n",
> +			    "VCPI %d for port %p not in topology, not creating a payload to remote\n",
>  			    payload->vcpi, payload->port);
> -		payload->vc_start_slot = -1;
> -		return 0;
> +		allocate = false;
>  	}
>  
> -	if (mgr->payload_count == 0)
> -		mgr->next_start_slot = mst_state->start_slot;
> -
> -	payload->vc_start_slot = mgr->next_start_slot;
> +	if (allocate) {
> +		ret = drm_dp_create_payload_at_dfp(mgr, payload);
> +		if (ret < 0)
> +			drm_warn(mgr->dev, "Failed to create MST payload for port %p: %d\n",
> +				 payload->port, ret);
>  
> -	ret = drm_dp_create_payload_step1(mgr, payload);
> -	drm_dp_mst_topology_put_port(port);
> -	if (ret < 0) {
> -		drm_warn(mgr->dev, "Failed to create MST payload for port %p: %d\n",
> -			 payload->port, ret);
> -		payload->vc_start_slot = -1;
> -		return ret;
>  	}
>  
> -	mgr->payload_count++;
> -	mgr->next_start_slot += payload->time_slots;
> +	payload->payload_allocation_status =
> +		(!allocate || ret < 0) ? DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL :
> +								DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
>  
> -	return 0;
> +	drm_dp_mst_topology_put_port(port);
> +
> +	return ret;
>  }
>  EXPORT_SYMBOL(drm_dp_add_payload_part1);
>  
>  /**
> - * drm_dp_remove_payload() - Remove an MST payload
> + * drm_dp_remove_payload_part1() - Remove an MST payload along the virtual channel
>   * @mgr: Manager to use.
>   * @mst_state: The MST atomic state
> - * @old_payload: The payload with its old state
> - * @new_payload: The payload to write
> + * @payload: The payload to remove
>   *
> - * Removes a payload from an MST topology if it was successfully assigned a start slot. Also updates
> - * the starting time slots of all other payloads which would have been shifted towards the start of
> - * the VC table as a result. After calling this, the driver should generate ACT and payload packets.
> + * Removes a payload along the virtual channel if it was successfully allocated.
> + * After calling this, the driver should set HW to generate ACT and then switch to new
> + * payload allocation state.
>   */
> -void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
> -			   struct drm_dp_mst_topology_state *mst_state,
> -			   const struct drm_dp_mst_atomic_payload *old_payload,
> -			   struct drm_dp_mst_atomic_payload *new_payload)
> +void drm_dp_remove_payload_part1(struct drm_dp_mst_topology_mgr *mgr,
> +				 struct drm_dp_mst_topology_state *mst_state,
> +				 struct drm_dp_mst_atomic_payload *payload)
>  {
> -	struct drm_dp_mst_atomic_payload *pos;
> +	/* Remove remote payload allocation */
>  	bool send_remove = false;
>  
> -	/* We failed to make the payload, so nothing to do */
> -	if (new_payload->vc_start_slot == -1)
> -		return;
> -
>  	mutex_lock(&mgr->lock);
> -	send_remove = drm_dp_mst_port_downstream_of_branch(new_payload->port, mgr->mst_primary);
> +	send_remove = drm_dp_mst_port_downstream_of_branch(payload->port, mgr->mst_primary);
>  	mutex_unlock(&mgr->lock);
>  
>  	if (send_remove)
> -		drm_dp_destroy_payload_step1(mgr, mst_state, new_payload);
> +		drm_dp_destroy_payload_at_remote_and_dfp(mgr, mst_state, payload);
>  	else
>  		drm_dbg_kms(mgr->dev, "Payload for VCPI %d not in topology, not sending remove\n",
> -			    new_payload->vcpi);
> +			    payload->vcpi);
> +
> +	payload->payload_allocation_status = DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL;
> +}
> +EXPORT_SYMBOL(drm_dp_remove_payload_part1);
>  
> +/**
> + * drm_dp_remove_payload_part2() - Remove an MST payload locally
> + * @mgr: Manager to use.
> + * @mst_state: The MST atomic state
> + * @old_payload: The payload with its old state
> + * @new_payload: The payload with its latest state
> + *
> + * Updates the starting time slots of all other payloads which would have been shifted towards
> + * the start of the payload ID table as a result of removing a payload. Driver should call this
> + * function whenever it removes a payload in its HW. It's independent to the result of payload
> + * allocation/deallocation at branch devices along the virtual channel.
> + */
> +void drm_dp_remove_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
> +				 struct drm_dp_mst_topology_state *mst_state,
> +				 const struct drm_dp_mst_atomic_payload *old_payload,
> +				 struct drm_dp_mst_atomic_payload *new_payload)
> +{
> +	struct drm_dp_mst_atomic_payload *pos;
> +
> +	/* Remove local payload allocation */
>  	list_for_each_entry(pos, &mst_state->payloads, next) {
>  		if (pos != new_payload && pos->vc_start_slot > new_payload->vc_start_slot)
>  			pos->vc_start_slot -= old_payload->time_slots;
> @@ -3382,9 +3409,10 @@ void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
>  
>  	if (new_payload->delete)
>  		drm_dp_mst_put_port_malloc(new_payload->port);
> -}
> -EXPORT_SYMBOL(drm_dp_remove_payload);
>  
> +	new_payload->payload_allocation_status = DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
> +}
> +EXPORT_SYMBOL(drm_dp_remove_payload_part2);
>  /**
>   * drm_dp_add_payload_part2() - Execute payload update part 2
>   * @mgr: Manager to use.
> @@ -3403,17 +3431,19 @@ int drm_dp_add_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
>  	int ret = 0;
>  
>  	/* Skip failed payloads */
> -	if (payload->vc_start_slot == -1) {
> -		drm_dbg_kms(mgr->dev, "Part 1 of payload creation for %s failed, skipping part 2\n",
> +	if (payload->payload_allocation_status != DRM_DP_MST_PAYLOAD_ALLOCATION_DFP) {
> +		drm_dbg_kms(state->dev, "Part 1 of payload creation for %s failed, skipping part 2\n",
>  			    payload->port->connector->name);
>  		return -EIO;
>  	}
>  
> -	ret = drm_dp_create_payload_step2(mgr, payload);
> -	if (ret < 0) {
> +	/* Allocate payload to remote end */
> +	ret = drm_dp_create_payload_to_remote(mgr, payload);
> +	if (ret < 0)
>  		drm_err(mgr->dev, "Step 2 of creating MST payload for %p failed: %d\n",
>  			payload->port, ret);
> -	}
> +	else
> +		payload->payload_allocation_status = DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE;
>  
>  	return ret;
>  }
> @@ -4324,6 +4354,7 @@ int drm_dp_atomic_find_time_slots(struct drm_atomic_state *state,
>  		drm_dp_mst_get_port_malloc(port);
>  		payload->port = port;
>  		payload->vc_start_slot = -1;
> +		payload->payload_allocation_status = DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
>  		list_add(&payload->next, &topology_state->payloads);
>  	}
>  	payload->time_slots = req_slots;
> @@ -4493,7 +4524,7 @@ void drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state *state)
>  		}
>  
>  		/* Now that previous state is committed, it's safe to copy over the start slot
> -		 * assignments
> +		 * and allocation status assignments
>  		 */
>  		list_for_each_entry(old_payload, &old_mst_state->payloads, next) {
>  			if (old_payload->delete)
> @@ -4502,6 +4533,8 @@ void drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state *state)
>  			new_payload = drm_atomic_get_mst_payload_state(new_mst_state,
>  								       old_payload->port);
>  			new_payload->vc_start_slot = old_payload->vc_start_slot;
> +			new_payload->payload_allocation_status =
> +							old_payload->payload_allocation_status;
>  		}
>  	}
>  }
> @@ -4818,6 +4851,13 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
>  	struct drm_dp_mst_atomic_payload *payload;
>  	int i, ret;
>  
> +	static const char *const status[] = {
> +		"None",
> +		"Local",
> +		"DFP",
> +		"Remote",
> +	};
> +
>  	mutex_lock(&mgr->lock);
>  	if (mgr->mst_primary)
>  		drm_dp_mst_dump_mstb(m, mgr->mst_primary);
> @@ -4834,7 +4874,7 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
>  	seq_printf(m, "payload_mask: %x, max_payloads: %d, start_slot: %u, pbn_div: %d\n",
>  		   state->payload_mask, mgr->max_payloads, state->start_slot, state->pbn_div);
>  
> -	seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc |     sink name     |\n");
> +	seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc | status |     sink name     |\n");
>  	for (i = 0; i < mgr->max_payloads; i++) {
>  		list_for_each_entry(payload, &state->payloads, next) {
>  			char name[14];
> @@ -4843,7 +4883,7 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
>  				continue;
>  
>  			fetch_monitor_name(mgr, payload->port, name, sizeof(name));
> -			seq_printf(m, " %5d %6d %6d %02d - %02d %5d %5s %19s\n",
> +			seq_printf(m, " %5d %6d %6d %02d - %02d %5d %5s %8s %19s\n",
>  				   i,
>  				   payload->port->port_num,
>  				   payload->vcpi,
> @@ -4851,6 +4891,7 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
>  				   payload->vc_start_slot + payload->time_slots - 1,
>  				   payload->pbn,
>  				   payload->dsc_enabled ? "Y" : "N",
> +				   status[payload->payload_allocation_status],
>  				   (*name != 0) ? name : "Unknown");
>  		}
>  	}
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> index e3f176a093d2..5f73cdabe7a1 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> @@ -557,12 +557,8 @@ static void intel_mst_disable_dp(struct intel_atomic_state *state,
>  	struct intel_dp *intel_dp = &dig_port->dp;
>  	struct intel_connector *connector =
>  		to_intel_connector(old_conn_state->connector);
> -	struct drm_dp_mst_topology_state *old_mst_state =
> -		drm_atomic_get_old_mst_topology_state(&state->base, &intel_dp->mst_mgr);
>  	struct drm_dp_mst_topology_state *new_mst_state =
>  		drm_atomic_get_new_mst_topology_state(&state->base, &intel_dp->mst_mgr);
> -	const struct drm_dp_mst_atomic_payload *old_payload =
> -		drm_atomic_get_mst_payload_state(old_mst_state, connector->port);
>  	struct drm_dp_mst_atomic_payload *new_payload =
>  		drm_atomic_get_mst_payload_state(new_mst_state, connector->port);
>  	struct drm_i915_private *i915 = to_i915(connector->base.dev);
> @@ -572,8 +568,7 @@ static void intel_mst_disable_dp(struct intel_atomic_state *state,
>  
>  	intel_hdcp_disable(intel_mst->connector);
>  
> -	drm_dp_remove_payload(&intel_dp->mst_mgr, new_mst_state,
> -			      old_payload, new_payload);
> +	drm_dp_remove_payload_part1(&intel_dp->mst_mgr, new_mst_state, new_payload);
>  
>  	intel_audio_codec_disable(encoder, old_crtc_state, old_conn_state);
>  }
> @@ -588,6 +583,14 @@ static void intel_mst_post_disable_dp(struct intel_atomic_state *state,
>  	struct intel_dp *intel_dp = &dig_port->dp;
>  	struct intel_connector *connector =
>  		to_intel_connector(old_conn_state->connector);
> +	struct drm_dp_mst_topology_state *old_mst_state =
> +		drm_atomic_get_old_mst_topology_state(&state->base, &intel_dp->mst_mgr);
> +	struct drm_dp_mst_topology_state *new_mst_state =
> +		drm_atomic_get_new_mst_topology_state(&state->base, &intel_dp->mst_mgr);
> +	const struct drm_dp_mst_atomic_payload *old_payload =
> +		drm_atomic_get_mst_payload_state(old_mst_state, connector->port);
> +	struct drm_dp_mst_atomic_payload *new_payload =
> +		drm_atomic_get_mst_payload_state(new_mst_state, connector->port);
>  	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
>  	bool last_mst_stream;
>  
> @@ -608,6 +611,9 @@ static void intel_mst_post_disable_dp(struct intel_atomic_state *state,
>  
>  	wait_for_act_sent(encoder, old_crtc_state);
>  
> +	drm_dp_remove_payload_part2(&intel_dp->mst_mgr, new_mst_state,
> +				    old_payload, new_payload);
> +
>  	intel_ddi_disable_transcoder_func(old_crtc_state);
>  
>  	if (DISPLAY_VER(dev_priv) >= 9)
> diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> index 4e7c9c353c51..bba01fa0780c 100644
> --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> @@ -882,21 +882,26 @@ struct nouveau_encoder *nv50_real_outp(struct drm_encoder *encoder)
>  
>  static void
>  nv50_msto_cleanup(struct drm_atomic_state *state,
> -		  struct drm_dp_mst_topology_state *mst_state,
> +		  struct drm_dp_mst_topology_state *new_mst_state,
>  		  struct drm_dp_mst_topology_mgr *mgr,
>  		  struct nv50_msto *msto)
>  {
>  	struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
> -	struct drm_dp_mst_atomic_payload *payload =
> -		drm_atomic_get_mst_payload_state(mst_state, msto->mstc->port);
> +	struct drm_dp_mst_atomic_payload *new_payload =
> +		drm_atomic_get_mst_payload_state(new_mst_state, msto->mstc->port);
> +	struct drm_dp_mst_topology_state *old_mst_state =
> +		drm_atomic_get_old_mst_topology_state(state, mgr);
> +	const struct drm_dp_mst_atomic_payload *old_payload =
> +		drm_atomic_get_mst_payload_state(old_mst_state, msto->mstc->port);
>  
>  	NV_ATOMIC(drm, "%s: msto cleanup\n", msto->encoder.name);
>  
>  	if (msto->disabled) {
>  		msto->mstc = NULL;
>  		msto->disabled = false;
> +		drm_dp_remove_payload_part2(mgr, new_mst_state, old_payload, new_payload);
>  	} else if (msto->enabled) {
> -		drm_dp_add_payload_part2(mgr, state, payload);
> +		drm_dp_add_payload_part2(mgr, state, new_payload);
>  		msto->enabled = false;
>  	}
>  }
> @@ -910,19 +915,15 @@ nv50_msto_prepare(struct drm_atomic_state *state,
>  	struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
>  	struct nv50_mstc *mstc = msto->mstc;
>  	struct nv50_mstm *mstm = mstc->mstm;
> -	struct drm_dp_mst_topology_state *old_mst_state;
> -	struct drm_dp_mst_atomic_payload *payload, *old_payload;
> +	struct drm_dp_mst_atomic_payload *payload;
>  
>  	NV_ATOMIC(drm, "%s: msto prepare\n", msto->encoder.name);
>  
> -	old_mst_state = drm_atomic_get_old_mst_topology_state(state, mgr);
> -
>  	payload = drm_atomic_get_mst_payload_state(mst_state, mstc->port);
> -	old_payload = drm_atomic_get_mst_payload_state(old_mst_state, mstc->port);
>  
>  	// TODO: Figure out if we want to do a better job of handling VCPI allocation failures here?
>  	if (msto->disabled) {
> -		drm_dp_remove_payload(mgr, mst_state, old_payload, payload);
> +		drm_dp_remove_payload_part1(mgr, mst_state, payload);
>  
>  		nvif_outp_dp_mst_vcpi(&mstm->outp->outp, msto->head->base.index, 0, 0, 0, 0);
>  	} else {
> diff --git a/include/drm/display/drm_dp_mst_helper.h b/include/drm/display/drm_dp_mst_helper.h
> index ed5c9660563c..4429d3b1745b 100644
> --- a/include/drm/display/drm_dp_mst_helper.h
> +++ b/include/drm/display/drm_dp_mst_helper.h
> @@ -46,6 +46,13 @@ struct drm_dp_mst_topology_ref_history {
>  };
>  #endif /* IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) */
>  
> +enum drm_dp_mst_payload_allocation {
> +	DRM_DP_MST_PAYLOAD_ALLOCATION_NONE,
> +	DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL,
> +	DRM_DP_MST_PAYLOAD_ALLOCATION_DFP,
> +	DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE,
> +};
> +
>  struct drm_dp_mst_branch;
>  
>  /**
> @@ -537,7 +544,7 @@ struct drm_dp_mst_atomic_payload {
>  	 *   drm_dp_mst_atomic_wait_for_dependencies() has been called, which will ensure the
>  	 *   previous MST states payload start slots have been copied over to the new state. Note
>  	 *   that a new start slot won't be assigned/removed from this payload until
> -	 *   drm_dp_add_payload_part1()/drm_dp_remove_payload() have been called.
> +	 *   drm_dp_add_payload_part1()/drm_dp_remove_payload_part2() have been called.
>  	 * * Acquire the MST modesetting lock, and then wait for any pending MST-related commits to
>  	 *   get committed to hardware by calling drm_crtc_commit_wait() on each of the
>  	 *   &drm_crtc_commit structs in &drm_dp_mst_topology_state.commit_deps.
> @@ -564,6 +571,9 @@ struct drm_dp_mst_atomic_payload {
>  	/** @dsc_enabled: Whether or not this payload has DSC enabled */
>  	bool dsc_enabled : 1;
>  
> +	/** @payload_allocation_status: The allocation status of this payload */
> +	enum drm_dp_mst_payload_allocation payload_allocation_status;
> +
>  	/** @next: The list node for this payload */
>  	struct list_head next;
>  };
> @@ -842,10 +852,13 @@ int drm_dp_add_payload_part1(struct drm_dp_mst_topology_mgr *mgr,
>  int drm_dp_add_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
>  			     struct drm_atomic_state *state,
>  			     struct drm_dp_mst_atomic_payload *payload);
> -void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
> -			   struct drm_dp_mst_topology_state *mst_state,
> -			   const struct drm_dp_mst_atomic_payload *old_payload,
> -			   struct drm_dp_mst_atomic_payload *new_payload);
> +void drm_dp_remove_payload_part1(struct drm_dp_mst_topology_mgr *mgr,
> +				 struct drm_dp_mst_topology_state *mst_state,
> +				 struct drm_dp_mst_atomic_payload *payload);
> +void drm_dp_remove_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
> +				 struct drm_dp_mst_topology_state *mst_state,
> +				 const struct drm_dp_mst_atomic_payload *old_payload,
> +				 struct drm_dp_mst_atomic_payload *new_payload);
>  
>  int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr);
>  

-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat

RE: [Patch v2 2/3] drm/mst: Refactor the flow for payload allocation/removement

[Lin, Wayne]

[AMD Official Use Only - General]

Thanks for your time, Lyude!

Regards,
Wayne

> -----Original Message-----
> From: Lyude Paul <lyude@redhat.com>
> Sent: Tuesday, August 8, 2023 4:23 AM
> To: Lin, Wayne <Wayne.Lin@amd.com>; dri-devel@lists.freedesktop.org;
> amd-gfx@lists.freedesktop.org
> Cc: jani.nikula@intel.com; ville.syrjala@linux.intel.com; imre.deak@intel.com;
> Wentland, Harry <Harry.Wentland@amd.com>; Zuo, Jerry
> <Jerry.Zuo@amd.com>
> Subject: Re: [Patch v2 2/3] drm/mst: Refactor the flow for payload
> allocation/removement
>
> Oooooo! This is a wonderful idea so far - keeping track of the status of
> allocations like this solves a lot of problems, especially with regards to the fact
> this actually seems to make it possible for us to have much better handling of
> payload failures in drivers - especially in situations like suspend/resume. The
> naming changes here are awesome too.
>
> I think this patch is good as far as I can tell review-wise! I haven't been able to
> test it quite yet but I'll do it asap.
>
> On Mon, 2023-08-07 at 10:56 +0800, Wayne Lin wrote:
> > [Why]
> > Today, the allocation/deallocation steps and status is a bit unclear.
> >
> > For instance, payload->vc_start_slot = -1 stands for "the failure of
> > updating DPCD payload ID table" and can also represent as "payload is
> > not allocated yet". These two cases should be handled differently and
> > hence better to distinguish them for better understanding.
> >
> > [How]
> > Define enumeration - ALLOCATION_LOCAL, ALLOCATION_DFP and
> > ALLOCATION_REMOTE to distinguish different allocation status. Adjust
> > the code to handle different status accordingly for better
> > understanding the sequence of payload allocation and payload
> removement.
> >
> > For payload creation, the procedure should look like this:
> > DRM part 1:
> > * step 1 - update sw mst mgr variables to add a new payload
> > * step 2 - add payload at immediate DFP DPCD payload table
> >
> > Driver:
> > * Add new payload in HW and sync up with DFP by sending ACT
> >
> > DRM Part 2:
> > * Send ALLOCATE_PAYLOAD sideband message to allocate bandwidth along
> the
> >   virtual channel.
> >
> > And as for payload removement, the procedure should look like this:
> > DRM part 1:
> > * step 1 - Send ALLOCATE_PAYLOAD sideband message to release bandwidth
> >            along the virtual channel
> > * step 2 - Clear payload allocation at immediate DFP DPCD payload
> > table
> >
> > Driver:
> > * Remove the payload in HW and sync up with DFP by sending ACT
> >
> > DRM part 2:
> > * update sw mst mgr variables to remove the payload
> >
> > Note that it's fine to fail when communicate with the branch device
> > connected at immediate downstrean-facing port, but updating variables
> > of SW mst mgr and HW configuration should be conducted anyway. That's
> > because it's under commit_tail and we need to complete the HW
> programming.
>
> yay!
>
> >
> > Changes since v1:
> > * Remove the set but not use variable 'old_payload' in function
> >   'nv50_msto_prepare'. Catched by kernel test robot <lkp@intel.com>
> >
> > Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
> > ---
> >  .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  20 ++-
> > drivers/gpu/drm/display/drm_dp_mst_topology.c | 159 +++++++++++------
> -
> >  drivers/gpu/drm/i915/display/intel_dp_mst.c   |  18 +-
> >  drivers/gpu/drm/nouveau/dispnv50/disp.c       |  21 +--
> >  include/drm/display/drm_dp_mst_helper.h       |  23 ++-
> >  5 files changed, 153 insertions(+), 88 deletions(-)
> >
> > diff --git
> a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > index d9a482908380..9ad509279b0a 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > @@ -219,7 +219,7 @@ static void dm_helpers_construct_old_payload(
> >     /* Set correct time_slots/PBN of old payload.
> >      * other fields (delete & dsc_enabled) in
> >      * struct drm_dp_mst_atomic_payload are don't care fields
> > -    * while calling drm_dp_remove_payload()
> > +    * while calling drm_dp_remove_payload_part2()
> >      */
> >     for (i = 0; i < current_link_table.stream_count; i++) {
> >             dc_alloc =
> > @@ -262,13 +262,12 @@ bool
> > dm_helpers_dp_mst_write_payload_allocation_table(
> >
> >     mst_mgr = &aconnector->mst_root->mst_mgr;
> >     mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
> > -
> > -   /* It's OK for this to fail */
> >     new_payload = drm_atomic_get_mst_payload_state(mst_state,
> > aconnector->mst_output_port);
> >
> >     if (enable) {
> >             target_payload = new_payload;
> >
> > +           /* It's OK for this to fail */
> >             drm_dp_add_payload_part1(mst_mgr, mst_state,
> new_payload);
> >     } else {
> >             /* construct old payload by VCPI*/
> > @@ -276,7 +275,7 @@ bool
> dm_helpers_dp_mst_write_payload_allocation_table(
> >                                             new_payload, &old_payload);
> >             target_payload = &old_payload;
> >
> > -           drm_dp_remove_payload(mst_mgr, mst_state,
> &old_payload, new_payload);
> > +           drm_dp_remove_payload_part1(mst_mgr, mst_state,
> new_payload);
> >     }
> >
> >     /* mst_mgr->->payloads are VC payload notify MST branch using
> DPCD
> > or @@ -342,7 +341,7 @@ bool
> dm_helpers_dp_mst_send_payload_allocation(
> >     struct amdgpu_dm_connector *aconnector;
> >     struct drm_dp_mst_topology_state *mst_state;
> >     struct drm_dp_mst_topology_mgr *mst_mgr;
> > -   struct drm_dp_mst_atomic_payload *payload;
> > +   struct drm_dp_mst_atomic_payload *new_payload, *old_payload;
> >     enum mst_progress_status set_flag =
> MST_ALLOCATE_NEW_PAYLOAD;
> >     enum mst_progress_status clr_flag =
> MST_CLEAR_ALLOCATED_PAYLOAD;
> >     int ret = 0;
> > @@ -355,15 +354,20 @@ bool
> dm_helpers_dp_mst_send_payload_allocation(
> >     mst_mgr = &aconnector->mst_root->mst_mgr;
> >     mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
> >
> > -   payload = drm_atomic_get_mst_payload_state(mst_state,
> aconnector->mst_output_port);
> > +   new_payload = drm_atomic_get_mst_payload_state(mst_state,
> > +aconnector->mst_output_port);
> >
> >     if (!enable) {
> >             set_flag = MST_CLEAR_ALLOCATED_PAYLOAD;
> >             clr_flag = MST_ALLOCATE_NEW_PAYLOAD;
> >     }
> >
> > -   if (enable)
> > -           ret = drm_dp_add_payload_part2(mst_mgr, mst_state-
> >base.state, payload);
> > +   if (enable) {
> > +           ret = drm_dp_add_payload_part2(mst_mgr, mst_state-
> >base.state, new_payload);
> > +   } else {
> > +           dm_helpers_construct_old_payload(stream->link, mst_state-
> >pbn_div,
> > +                                            new_payload, old_payload);
> > +           drm_dp_remove_payload_part2(mst_mgr, mst_state,
> old_payload, new_payload);
> > +   }
> >
> >     if (ret) {
> >             amdgpu_dm_set_mst_status(&aconnector->mst_status,
> > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > index 4d80426757ab..e04f87ff755a 100644
> > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > @@ -3255,15 +3255,15 @@ int
> drm_dp_send_query_stream_enc_status(struct
> > drm_dp_mst_topology_mgr *mgr,  }
> > EXPORT_SYMBOL(drm_dp_send_query_stream_enc_status);
> >
> > -static int drm_dp_create_payload_step1(struct drm_dp_mst_topology_mgr
> *mgr,
> > -                                  struct drm_dp_mst_atomic_payload
> *payload)
> > +static int drm_dp_create_payload_at_dfp(struct
> drm_dp_mst_topology_mgr *mgr,
> > +                                   struct drm_dp_mst_atomic_payload
> *payload)
> >  {
> >     return drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload-
> >vc_start_slot,
> >                                      payload->time_slots);
> >  }
> >
> > -static int drm_dp_create_payload_step2(struct drm_dp_mst_topology_mgr
> *mgr,
> > -                                  struct drm_dp_mst_atomic_payload
> *payload)
> > +static int drm_dp_create_payload_to_remote(struct
> drm_dp_mst_topology_mgr *mgr,
> > +                                      struct drm_dp_mst_atomic_payload
> *payload)
> >  {
> >     int ret;
> >     struct drm_dp_mst_port *port =
> > drm_dp_mst_topology_get_port_validated(mgr, payload->port); @@ -
> 3276,17 +3276,20 @@ static int drm_dp_create_payload_step2(struct
> drm_dp_mst_topology_mgr *mgr,
> >     return ret;
> >  }
> >
> > -static int drm_dp_destroy_payload_step1(struct
> drm_dp_mst_topology_mgr *mgr,
> > -                                   struct drm_dp_mst_topology_state
> *mst_state,
> > -                                   struct drm_dp_mst_atomic_payload
> *payload)
> > +static void drm_dp_destroy_payload_at_remote_and_dfp(struct
> drm_dp_mst_topology_mgr *mgr,
> > +                                                struct
> drm_dp_mst_topology_state *mst_state,
> > +                                                struct
> drm_dp_mst_atomic_payload *payload)
> >  {
> >     drm_dbg_kms(mgr->dev, "\n");
> >
> >     /* it's okay for these to fail */
> > -   drm_dp_payload_send_msg(mgr, payload->port, payload->vcpi, 0);
> > -   drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload-
> >vc_start_slot, 0);
> > +   if (payload->payload_allocation_status ==
> DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE) {
> > +           drm_dp_payload_send_msg(mgr, payload->port, payload-
> >vcpi, 0);
> > +           payload->payload_allocation_status =
> DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
> > +   }
> >
> > -   return 0;
> > +   if (payload->payload_allocation_status ==
> DRM_DP_MST_PAYLOAD_ALLOCATION_DFP)
> > +           drm_dp_dpcd_write_payload(mgr, payload->vcpi,
> > +payload->vc_start_slot, 0);
> >  }
> >
> >  /**
> > @@ -3296,81 +3299,105 @@ static int
> drm_dp_destroy_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
> >   * @payload: The payload to write
> >   *
> >   * Determines the starting time slot for the given payload, and
> > programs the VCPI for this payload
> > - * into hardware. After calling this, the driver should generate ACT and
> payload packets.
> > + * into the DPCD of DPRX. After calling this, the driver should generate ACT
> and payload packets.
> >   *
> > - * Returns: 0 on success, error code on failure. In the event that
> > this fails,
> > - * @payload.vc_start_slot will also be set to -1.
> > + * Returns: 0 on success, error code on failure.
> >   */
> >  int drm_dp_add_payload_part1(struct drm_dp_mst_topology_mgr *mgr,
> >                          struct drm_dp_mst_topology_state *mst_state,
> >                          struct drm_dp_mst_atomic_payload *payload)  {
> >     struct drm_dp_mst_port *port;
> > -   int ret;
> > +   int ret = 0;
> > +   bool allocate = true;
> > +
> > +   /* Update mst mgr info */
> > +   if (mgr->payload_count == 0)
> > +           mgr->next_start_slot = mst_state->start_slot;
> > +
> > +   payload->vc_start_slot = mgr->next_start_slot;
> > +
> > +   mgr->payload_count++;
> > +   mgr->next_start_slot += payload->time_slots;
> >
> > +   /* Allocate payload to immediate downstream facing port */
> >     port = drm_dp_mst_topology_get_port_validated(mgr, payload-
> >port);
> >     if (!port) {
> >             drm_dbg_kms(mgr->dev,
> > -                       "VCPI %d for port %p not in topology, not creating a
> payload\n",
> > +                       "VCPI %d for port %p not in topology, not creating a
> payload
> > +to remote\n",
> >                         payload->vcpi, payload->port);
> > -           payload->vc_start_slot = -1;
> > -           return 0;
> > +           allocate = false;
> >     }
> >
> > -   if (mgr->payload_count == 0)
> > -           mgr->next_start_slot = mst_state->start_slot;
> > -
> > -   payload->vc_start_slot = mgr->next_start_slot;
> > +   if (allocate) {
> > +           ret = drm_dp_create_payload_at_dfp(mgr, payload);
> > +           if (ret < 0)
> > +                   drm_warn(mgr->dev, "Failed to create MST payload
> for port %p: %d\n",
> > +                            payload->port, ret);
> >
> > -   ret = drm_dp_create_payload_step1(mgr, payload);
> > -   drm_dp_mst_topology_put_port(port);
> > -   if (ret < 0) {
> > -           drm_warn(mgr->dev, "Failed to create MST payload for port
> %p: %d\n",
> > -                    payload->port, ret);
> > -           payload->vc_start_slot = -1;
> > -           return ret;
> >     }
> >
> > -   mgr->payload_count++;
> > -   mgr->next_start_slot += payload->time_slots;
> > +   payload->payload_allocation_status =
> > +           (!allocate || ret < 0) ?
> DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL :
> > +
>       DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
> >
> > -   return 0;
> > +   drm_dp_mst_topology_put_port(port);
> > +
> > +   return ret;
> >  }
> >  EXPORT_SYMBOL(drm_dp_add_payload_part1);
> >
> >  /**
> > - * drm_dp_remove_payload() - Remove an MST payload
> > + * drm_dp_remove_payload_part1() - Remove an MST payload along the
> > + virtual channel
> >   * @mgr: Manager to use.
> >   * @mst_state: The MST atomic state
> > - * @old_payload: The payload with its old state
> > - * @new_payload: The payload to write
> > + * @payload: The payload to remove
> >   *
> > - * Removes a payload from an MST topology if it was successfully
> > assigned a start slot. Also updates
> > - * the starting time slots of all other payloads which would have
> > been shifted towards the start of
> > - * the VC table as a result. After calling this, the driver should generate ACT
> and payload packets.
> > + * Removes a payload along the virtual channel if it was successfully
> allocated.
> > + * After calling this, the driver should set HW to generate ACT and
> > + then switch to new
> > + * payload allocation state.
> >   */
> > -void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
> > -                      struct drm_dp_mst_topology_state *mst_state,
> > -                      const struct drm_dp_mst_atomic_payload
> *old_payload,
> > -                      struct drm_dp_mst_atomic_payload *new_payload)
> > +void drm_dp_remove_payload_part1(struct drm_dp_mst_topology_mgr
> *mgr,
> > +                            struct drm_dp_mst_topology_state
> *mst_state,
> > +                            struct drm_dp_mst_atomic_payload
> *payload)
> >  {
> > -   struct drm_dp_mst_atomic_payload *pos;
> > +   /* Remove remote payload allocation */
> >     bool send_remove = false;
> >
> > -   /* We failed to make the payload, so nothing to do */
> > -   if (new_payload->vc_start_slot == -1)
> > -           return;
> > -
> >     mutex_lock(&mgr->lock);
> > -   send_remove =
> drm_dp_mst_port_downstream_of_branch(new_payload->port, mgr-
> >mst_primary);
> > +   send_remove = drm_dp_mst_port_downstream_of_branch(payload-
> >port,
> > +mgr->mst_primary);
> >     mutex_unlock(&mgr->lock);
> >
> >     if (send_remove)
> > -           drm_dp_destroy_payload_step1(mgr, mst_state,
> new_payload);
> > +           drm_dp_destroy_payload_at_remote_and_dfp(mgr,
> mst_state, payload);
> >     else
> >             drm_dbg_kms(mgr->dev, "Payload for VCPI %d not in
> topology, not sending remove\n",
> > -                       new_payload->vcpi);
> > +                       payload->vcpi);
> > +
> > +   payload->payload_allocation_status =
> > +DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL;
> > +}
> > +EXPORT_SYMBOL(drm_dp_remove_payload_part1);
> >
> > +/**
> > + * drm_dp_remove_payload_part2() - Remove an MST payload locally
> > + * @mgr: Manager to use.
> > + * @mst_state: The MST atomic state
> > + * @old_payload: The payload with its old state
> > + * @new_payload: The payload with its latest state
> > + *
> > + * Updates the starting time slots of all other payloads which would
> > +have been shifted towards
> > + * the start of the payload ID table as a result of removing a
> > +payload. Driver should call this
> > + * function whenever it removes a payload in its HW. It's independent
> > +to the result of payload
> > + * allocation/deallocation at branch devices along the virtual channel.
> > + */
> > +void drm_dp_remove_payload_part2(struct drm_dp_mst_topology_mgr
> *mgr,
> > +                            struct drm_dp_mst_topology_state
> *mst_state,
> > +                            const struct drm_dp_mst_atomic_payload
> *old_payload,
> > +                            struct drm_dp_mst_atomic_payload
> *new_payload) {
> > +   struct drm_dp_mst_atomic_payload *pos;
> > +
> > +   /* Remove local payload allocation */
> >     list_for_each_entry(pos, &mst_state->payloads, next) {
> >             if (pos != new_payload && pos->vc_start_slot > new_payload-
> >vc_start_slot)
> >                     pos->vc_start_slot -= old_payload->time_slots; @@ -
> 3382,9 +3409,10
> > @@ void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr
> *mgr,
> >
> >     if (new_payload->delete)
> >             drm_dp_mst_put_port_malloc(new_payload->port);
> > -}
> > -EXPORT_SYMBOL(drm_dp_remove_payload);
> >
> > +   new_payload->payload_allocation_status =
> > +DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
> > +}
> > +EXPORT_SYMBOL(drm_dp_remove_payload_part2);
> >  /**
> >   * drm_dp_add_payload_part2() - Execute payload update part 2
> >   * @mgr: Manager to use.
> > @@ -3403,17 +3431,19 @@ int drm_dp_add_payload_part2(struct
> drm_dp_mst_topology_mgr *mgr,
> >     int ret = 0;
> >
> >     /* Skip failed payloads */
> > -   if (payload->vc_start_slot == -1) {
> > -           drm_dbg_kms(mgr->dev, "Part 1 of payload creation for %s
> failed, skipping part 2\n",
> > +   if (payload->payload_allocation_status !=
> DRM_DP_MST_PAYLOAD_ALLOCATION_DFP) {
> > +           drm_dbg_kms(state->dev, "Part 1 of payload creation for %s
> failed,
> > +skipping part 2\n",
> >                         payload->port->connector->name);
> >             return -EIO;
> >     }
> >
> > -   ret = drm_dp_create_payload_step2(mgr, payload);
> > -   if (ret < 0) {
> > +   /* Allocate payload to remote end */
> > +   ret = drm_dp_create_payload_to_remote(mgr, payload);
> > +   if (ret < 0)
> >             drm_err(mgr->dev, "Step 2 of creating MST payload for %p
> failed: %d\n",
> >                     payload->port, ret);
> > -   }
> > +   else
> > +           payload->payload_allocation_status =
> > +DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE;
> >
> >     return ret;
> >  }
> > @@ -4324,6 +4354,7 @@ int drm_dp_atomic_find_time_slots(struct
> drm_atomic_state *state,
> >             drm_dp_mst_get_port_malloc(port);
> >             payload->port = port;
> >             payload->vc_start_slot = -1;
> > +           payload->payload_allocation_status =
> > +DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
> >             list_add(&payload->next, &topology_state->payloads);
> >     }
> >     payload->time_slots = req_slots;
> > @@ -4493,7 +4524,7 @@ void
> drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state
> *state)
> >             }
> >
> >             /* Now that previous state is committed, it's safe to copy over
> the start slot
> > -            * assignments
> > +            * and allocation status assignments
> >              */
> >             list_for_each_entry(old_payload, &old_mst_state->payloads,
> next) {
> >                     if (old_payload->delete)
> > @@ -4502,6 +4533,8 @@ void
> drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state
> *state)
> >                     new_payload =
> drm_atomic_get_mst_payload_state(new_mst_state,
> >
> old_payload->port);
> >                     new_payload->vc_start_slot = old_payload-
> >vc_start_slot;
> > +                   new_payload->payload_allocation_status =
> > +                                                   old_payload-
> >payload_allocation_status;
> >             }
> >     }
> >  }
> > @@ -4818,6 +4851,13 @@ void drm_dp_mst_dump_topology(struct
> seq_file *m,
> >     struct drm_dp_mst_atomic_payload *payload;
> >     int i, ret;
> >
> > +   static const char *const status[] = {
> > +           "None",
> > +           "Local",
> > +           "DFP",
> > +           "Remote",
> > +   };
> > +
> >     mutex_lock(&mgr->lock);
> >     if (mgr->mst_primary)
> >             drm_dp_mst_dump_mstb(m, mgr->mst_primary); @@ -
> 4834,7 +4874,7 @@
> > void drm_dp_mst_dump_topology(struct seq_file *m,
> >     seq_printf(m, "payload_mask: %x, max_payloads: %d, start_slot: %u,
> pbn_div: %d\n",
> >                state->payload_mask, mgr->max_payloads, state-
> >start_slot,
> > state->pbn_div);
> >
> > -   seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc |     sink name
> |\n");
> > +   seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc | status |     sink
> name     |\n");
> >     for (i = 0; i < mgr->max_payloads; i++) {
> >             list_for_each_entry(payload, &state->payloads, next) {
> >                     char name[14];
> > @@ -4843,7 +4883,7 @@ void drm_dp_mst_dump_topology(struct
> seq_file *m,
> >                             continue;
> >
> >                     fetch_monitor_name(mgr, payload->port, name,
> sizeof(name));
> > -                   seq_printf(m, " %5d %6d %6d %02d - %02d %5d %5s
> %19s\n",
> > +                   seq_printf(m, " %5d %6d %6d %02d - %02d %5d %5s
> %8s %19s\n",
> >                                i,
> >                                payload->port->port_num,
> >                                payload->vcpi,
> > @@ -4851,6 +4891,7 @@ void drm_dp_mst_dump_topology(struct
> seq_file *m,
> >                                payload->vc_start_slot + payload-
> >time_slots - 1,
> >                                payload->pbn,
> >                                payload->dsc_enabled ? "Y" : "N",
> > +                              status[payload->payload_allocation_status],
> >                                (*name != 0) ? name : "Unknown");
> >             }
> >     }
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > index e3f176a093d2..5f73cdabe7a1 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > @@ -557,12 +557,8 @@ static void intel_mst_disable_dp(struct
> intel_atomic_state *state,
> >     struct intel_dp *intel_dp = &dig_port->dp;
> >     struct intel_connector *connector =
> >             to_intel_connector(old_conn_state->connector);
> > -   struct drm_dp_mst_topology_state *old_mst_state =
> > -           drm_atomic_get_old_mst_topology_state(&state->base,
> &intel_dp->mst_mgr);
> >     struct drm_dp_mst_topology_state *new_mst_state =
> >             drm_atomic_get_new_mst_topology_state(&state->base,
> &intel_dp->mst_mgr);
> > -   const struct drm_dp_mst_atomic_payload *old_payload =
> > -           drm_atomic_get_mst_payload_state(old_mst_state,
> connector->port);
> >     struct drm_dp_mst_atomic_payload *new_payload =
> >             drm_atomic_get_mst_payload_state(new_mst_state,
> connector->port);
> >     struct drm_i915_private *i915 = to_i915(connector->base.dev); @@
> > -572,8 +568,7 @@ static void intel_mst_disable_dp(struct
> > intel_atomic_state *state,
> >
> >     intel_hdcp_disable(intel_mst->connector);
> >
> > -   drm_dp_remove_payload(&intel_dp->mst_mgr, new_mst_state,
> > -                         old_payload, new_payload);
> > +   drm_dp_remove_payload_part1(&intel_dp->mst_mgr,
> new_mst_state,
> > +new_payload);
> >
> >     intel_audio_codec_disable(encoder, old_crtc_state, old_conn_state);
> > } @@ -588,6 +583,14 @@ static void intel_mst_post_disable_dp(struct
> > intel_atomic_state *state,
> >     struct intel_dp *intel_dp = &dig_port->dp;
> >     struct intel_connector *connector =
> >             to_intel_connector(old_conn_state->connector);
> > +   struct drm_dp_mst_topology_state *old_mst_state =
> > +           drm_atomic_get_old_mst_topology_state(&state->base,
> &intel_dp->mst_mgr);
> > +   struct drm_dp_mst_topology_state *new_mst_state =
> > +           drm_atomic_get_new_mst_topology_state(&state->base,
> &intel_dp->mst_mgr);
> > +   const struct drm_dp_mst_atomic_payload *old_payload =
> > +           drm_atomic_get_mst_payload_state(old_mst_state,
> connector->port);
> > +   struct drm_dp_mst_atomic_payload *new_payload =
> > +           drm_atomic_get_mst_payload_state(new_mst_state,
> connector->port);
> >     struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
> >     bool last_mst_stream;
> >
> > @@ -608,6 +611,9 @@ static void intel_mst_post_disable_dp(struct
> > intel_atomic_state *state,
> >
> >     wait_for_act_sent(encoder, old_crtc_state);
> >
> > +   drm_dp_remove_payload_part2(&intel_dp->mst_mgr,
> new_mst_state,
> > +                               old_payload, new_payload);
> > +
> >     intel_ddi_disable_transcoder_func(old_crtc_state);
> >
> >     if (DISPLAY_VER(dev_priv) >= 9)
> > diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > index 4e7c9c353c51..bba01fa0780c 100644
> > --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > @@ -882,21 +882,26 @@ struct nouveau_encoder *nv50_real_outp(struct
> > drm_encoder *encoder)
> >
> >  static void
> >  nv50_msto_cleanup(struct drm_atomic_state *state,
> > -             struct drm_dp_mst_topology_state *mst_state,
> > +             struct drm_dp_mst_topology_state *new_mst_state,
> >               struct drm_dp_mst_topology_mgr *mgr,
> >               struct nv50_msto *msto)
> >  {
> >     struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
> > -   struct drm_dp_mst_atomic_payload *payload =
> > -           drm_atomic_get_mst_payload_state(mst_state, msto->mstc-
> >port);
> > +   struct drm_dp_mst_atomic_payload *new_payload =
> > +           drm_atomic_get_mst_payload_state(new_mst_state, msto-
> >mstc->port);
> > +   struct drm_dp_mst_topology_state *old_mst_state =
> > +           drm_atomic_get_old_mst_topology_state(state, mgr);
> > +   const struct drm_dp_mst_atomic_payload *old_payload =
> > +           drm_atomic_get_mst_payload_state(old_mst_state, msto-
> >mstc->port);
> >
> >     NV_ATOMIC(drm, "%s: msto cleanup\n", msto->encoder.name);
> >
> >     if (msto->disabled) {
> >             msto->mstc = NULL;
> >             msto->disabled = false;
> > +           drm_dp_remove_payload_part2(mgr, new_mst_state,
> old_payload,
> > +new_payload);
> >     } else if (msto->enabled) {
> > -           drm_dp_add_payload_part2(mgr, state, payload);
> > +           drm_dp_add_payload_part2(mgr, state, new_payload);
> >             msto->enabled = false;
> >     }
> >  }
> > @@ -910,19 +915,15 @@ nv50_msto_prepare(struct drm_atomic_state
> *state,
> >     struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
> >     struct nv50_mstc *mstc = msto->mstc;
> >     struct nv50_mstm *mstm = mstc->mstm;
> > -   struct drm_dp_mst_topology_state *old_mst_state;
> > -   struct drm_dp_mst_atomic_payload *payload, *old_payload;
> > +   struct drm_dp_mst_atomic_payload *payload;
> >
> >     NV_ATOMIC(drm, "%s: msto prepare\n", msto->encoder.name);
> >
> > -   old_mst_state = drm_atomic_get_old_mst_topology_state(state,
> mgr);
> > -
> >     payload = drm_atomic_get_mst_payload_state(mst_state, mstc-
> >port);
> > -   old_payload = drm_atomic_get_mst_payload_state(old_mst_state,
> mstc->port);
> >
> >     // TODO: Figure out if we want to do a better job of handling VCPI
> allocation failures here?
> >     if (msto->disabled) {
> > -           drm_dp_remove_payload(mgr, mst_state, old_payload,
> payload);
> > +           drm_dp_remove_payload_part1(mgr, mst_state, payload);
> >
> >             nvif_outp_dp_mst_vcpi(&mstm->outp->outp, msto->head-
> >base.index, 0, 0, 0, 0);
> >     } else {
> > diff --git a/include/drm/display/drm_dp_mst_helper.h
> > b/include/drm/display/drm_dp_mst_helper.h
> > index ed5c9660563c..4429d3b1745b 100644
> > --- a/include/drm/display/drm_dp_mst_helper.h
> > +++ b/include/drm/display/drm_dp_mst_helper.h
> > @@ -46,6 +46,13 @@ struct drm_dp_mst_topology_ref_history {  };
> > #endif /* IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) */
> >
> > +enum drm_dp_mst_payload_allocation {
> > +   DRM_DP_MST_PAYLOAD_ALLOCATION_NONE,
> > +   DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL,
> > +   DRM_DP_MST_PAYLOAD_ALLOCATION_DFP,
> > +   DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE,
> > +};
> > +
> >  struct drm_dp_mst_branch;
> >
> >  /**
> > @@ -537,7 +544,7 @@ struct drm_dp_mst_atomic_payload {
> >      *   drm_dp_mst_atomic_wait_for_dependencies() has been called,
> which will ensure the
> >      *   previous MST states payload start slots have been copied over to
> the new state. Note
> >      *   that a new start slot won't be assigned/removed from this payload
> until
> > -    *   drm_dp_add_payload_part1()/drm_dp_remove_payload() have
> been called.
> > +    *   drm_dp_add_payload_part1()/drm_dp_remove_payload_part2()
> have been called.
> >      * * Acquire the MST modesetting lock, and then wait for any pending
> MST-related commits to
> >      *   get committed to hardware by calling drm_crtc_commit_wait() on
> each of the
> >      *   &drm_crtc_commit structs in
> &drm_dp_mst_topology_state.commit_deps.
> > @@ -564,6 +571,9 @@ struct drm_dp_mst_atomic_payload {
> >     /** @dsc_enabled: Whether or not this payload has DSC enabled */
> >     bool dsc_enabled : 1;
> >
> > +   /** @payload_allocation_status: The allocation status of this payload
> */
> > +   enum drm_dp_mst_payload_allocation payload_allocation_status;
> > +
> >     /** @next: The list node for this payload */
> >     struct list_head next;
> >  };
> > @@ -842,10 +852,13 @@ int drm_dp_add_payload_part1(struct
> > drm_dp_mst_topology_mgr *mgr,  int drm_dp_add_payload_part2(struct
> drm_dp_mst_topology_mgr *mgr,
> >                          struct drm_atomic_state *state,
> >                          struct drm_dp_mst_atomic_payload *payload); -
> void
> > drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
> > -                      struct drm_dp_mst_topology_state *mst_state,
> > -                      const struct drm_dp_mst_atomic_payload
> *old_payload,
> > -                      struct drm_dp_mst_atomic_payload
> *new_payload);
> > +void drm_dp_remove_payload_part1(struct drm_dp_mst_topology_mgr
> *mgr,
> > +                            struct drm_dp_mst_topology_state
> *mst_state,
> > +                            struct drm_dp_mst_atomic_payload
> *payload); void
> > +drm_dp_remove_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
> > +                            struct drm_dp_mst_topology_state
> *mst_state,
> > +                            const struct drm_dp_mst_atomic_payload
> *old_payload,
> > +                            struct drm_dp_mst_atomic_payload
> *new_payload);
> >
> >  int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr);
> >
>
> --
> Cheers,
>  Lyude Paul (she/her)
>  Software Engineer at Red Hat

Re: [Patch v2 2/3] drm/mst: Refactor the flow for payload allocation/removement

[Lyude Paul]

Two small comments:

On Mon, 2023-08-07 at 10:56 +0800, Wayne Lin wrote:
> [Why]
> Today, the allocation/deallocation steps and status is a bit unclear.
> 
> For instance, payload->vc_start_slot = -1 stands for "the failure of
> updating DPCD payload ID table" and can also represent as "payload is not
> allocated yet". These two cases should be handled differently and hence
> better to distinguish them for better understanding.
> 
> [How]
> Define enumeration - ALLOCATION_LOCAL, ALLOCATION_DFP and ALLOCATION_REMOTE
> to distinguish different allocation status. Adjust the code to handle
> different status accordingly for better understanding the sequence of
> payload allocation and payload removement.
> 
> For payload creation, the procedure should look like this:
> DRM part 1:
> * step 1 - update sw mst mgr variables to add a new payload
> * step 2 - add payload at immediate DFP DPCD payload table
> 
> Driver:
> * Add new payload in HW and sync up with DFP by sending ACT
> 
> DRM Part 2:
> * Send ALLOCATE_PAYLOAD sideband message to allocate bandwidth along the
>   virtual channel.
> 
> And as for payload removement, the procedure should look like this:
> DRM part 1:
> * step 1 - Send ALLOCATE_PAYLOAD sideband message to release bandwidth
>            along the virtual channel
> * step 2 - Clear payload allocation at immediate DFP DPCD payload table
> 
> Driver:
> * Remove the payload in HW and sync up with DFP by sending ACT
> 
> DRM part 2:
> * update sw mst mgr variables to remove the payload
> 
> Note that it's fine to fail when communicate with the branch device
> connected at immediate downstrean-facing port, but updating variables of
> SW mst mgr and HW configuration should be conducted anyway. That's because
> it's under commit_tail and we need to complete the HW programming.
> 
> Changes since v1:
> * Remove the set but not use variable 'old_payload' in function
>   'nv50_msto_prepare'. Catched by kernel test robot <lkp@intel.com>
> 
> Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
> ---
>  .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  20 ++-
>  drivers/gpu/drm/display/drm_dp_mst_topology.c | 159 +++++++++++-------
>  drivers/gpu/drm/i915/display/intel_dp_mst.c   |  18 +-
>  drivers/gpu/drm/nouveau/dispnv50/disp.c       |  21 +--
>  include/drm/display/drm_dp_mst_helper.h       |  23 ++-
>  5 files changed, 153 insertions(+), 88 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> index d9a482908380..9ad509279b0a 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> @@ -219,7 +219,7 @@ static void dm_helpers_construct_old_payload(
>  	/* Set correct time_slots/PBN of old payload.
>  	 * other fields (delete & dsc_enabled) in
>  	 * struct drm_dp_mst_atomic_payload are don't care fields
> -	 * while calling drm_dp_remove_payload()
> +	 * while calling drm_dp_remove_payload_part2()
>  	 */
>  	for (i = 0; i < current_link_table.stream_count; i++) {
>  		dc_alloc =
> @@ -262,13 +262,12 @@ bool dm_helpers_dp_mst_write_payload_allocation_table(
>  
>  	mst_mgr = &aconnector->mst_root->mst_mgr;
>  	mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
> -
> -	/* It's OK for this to fail */
>  	new_payload = drm_atomic_get_mst_payload_state(mst_state, aconnector->mst_output_port);
>  
>  	if (enable) {
>  		target_payload = new_payload;
>  
> +		/* It's OK for this to fail */
>  		drm_dp_add_payload_part1(mst_mgr, mst_state, new_payload);
>  	} else {
>  		/* construct old payload by VCPI*/
> @@ -276,7 +275,7 @@ bool dm_helpers_dp_mst_write_payload_allocation_table(
>  						new_payload, &old_payload);
>  		target_payload = &old_payload;
>  
> -		drm_dp_remove_payload(mst_mgr, mst_state, &old_payload, new_payload);
> +		drm_dp_remove_payload_part1(mst_mgr, mst_state, new_payload);
>  	}
>  
>  	/* mst_mgr->->payloads are VC payload notify MST branch using DPCD or
> @@ -342,7 +341,7 @@ bool dm_helpers_dp_mst_send_payload_allocation(
>  	struct amdgpu_dm_connector *aconnector;
>  	struct drm_dp_mst_topology_state *mst_state;
>  	struct drm_dp_mst_topology_mgr *mst_mgr;
> -	struct drm_dp_mst_atomic_payload *payload;
> +	struct drm_dp_mst_atomic_payload *new_payload, *old_payload;
>  	enum mst_progress_status set_flag = MST_ALLOCATE_NEW_PAYLOAD;
>  	enum mst_progress_status clr_flag = MST_CLEAR_ALLOCATED_PAYLOAD;
>  	int ret = 0;
> @@ -355,15 +354,20 @@ bool dm_helpers_dp_mst_send_payload_allocation(
>  	mst_mgr = &aconnector->mst_root->mst_mgr;
>  	mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
>  
> -	payload = drm_atomic_get_mst_payload_state(mst_state, aconnector->mst_output_port);
> +	new_payload = drm_atomic_get_mst_payload_state(mst_state, aconnector->mst_output_port);
>  
>  	if (!enable) {
>  		set_flag = MST_CLEAR_ALLOCATED_PAYLOAD;
>  		clr_flag = MST_ALLOCATE_NEW_PAYLOAD;
>  	}
>  
> -	if (enable)
> -		ret = drm_dp_add_payload_part2(mst_mgr, mst_state->base.state, payload);
> +	if (enable) {
> +		ret = drm_dp_add_payload_part2(mst_mgr, mst_state->base.state, new_payload);
> +	} else {
> +		dm_helpers_construct_old_payload(stream->link, mst_state->pbn_div,
> +						 new_payload, old_payload);
> +		drm_dp_remove_payload_part2(mst_mgr, mst_state, old_payload, new_payload);
> +	}
>  
>  	if (ret) {
>  		amdgpu_dm_set_mst_status(&aconnector->mst_status,
> diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> index 4d80426757ab..e04f87ff755a 100644
> --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> @@ -3255,15 +3255,15 @@ int drm_dp_send_query_stream_enc_status(struct drm_dp_mst_topology_mgr *mgr,
>  }
>  EXPORT_SYMBOL(drm_dp_send_query_stream_enc_status);
>  
> -static int drm_dp_create_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
> -				       struct drm_dp_mst_atomic_payload *payload)
> +static int drm_dp_create_payload_at_dfp(struct drm_dp_mst_topology_mgr *mgr,
> +					struct drm_dp_mst_atomic_payload *payload)
>  {
>  	return drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload->vc_start_slot,
>  					 payload->time_slots);
>  }
>  
> -static int drm_dp_create_payload_step2(struct drm_dp_mst_topology_mgr *mgr,
> -				       struct drm_dp_mst_atomic_payload *payload)
> +static int drm_dp_create_payload_to_remote(struct drm_dp_mst_topology_mgr *mgr,
> +					   struct drm_dp_mst_atomic_payload *payload)
>  {
>  	int ret;
>  	struct drm_dp_mst_port *port = drm_dp_mst_topology_get_port_validated(mgr, payload->port);
> @@ -3276,17 +3276,20 @@ static int drm_dp_create_payload_step2(struct drm_dp_mst_topology_mgr *mgr,
>  	return ret;
>  }
>  
> -static int drm_dp_destroy_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
> -					struct drm_dp_mst_topology_state *mst_state,
> -					struct drm_dp_mst_atomic_payload *payload)
> +static void drm_dp_destroy_payload_at_remote_and_dfp(struct drm_dp_mst_topology_mgr *mgr,
> +						     struct drm_dp_mst_topology_state *mst_state,
> +						     struct drm_dp_mst_atomic_payload *payload)
>  {
>  	drm_dbg_kms(mgr->dev, "\n");
>  
>  	/* it's okay for these to fail */
> -	drm_dp_payload_send_msg(mgr, payload->port, payload->vcpi, 0);
> -	drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload->vc_start_slot, 0);
> +	if (payload->payload_allocation_status == DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE) {
> +		drm_dp_payload_send_msg(mgr, payload->port, payload->vcpi, 0);
> +		payload->payload_allocation_status = DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
> +	}
>  
> -	return 0;
> +	if (payload->payload_allocation_status == DRM_DP_MST_PAYLOAD_ALLOCATION_DFP)
> +		drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload->vc_start_slot, 0);
>  }
>  
>  /**
> @@ -3296,81 +3299,105 @@ static int drm_dp_destroy_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
>   * @payload: The payload to write
>   *
>   * Determines the starting time slot for the given payload, and programs the VCPI for this payload
> - * into hardware. After calling this, the driver should generate ACT and payload packets.
> + * into the DPCD of DPRX. After calling this, the driver should generate ACT and payload packets.
>   *
> - * Returns: 0 on success, error code on failure. In the event that this fails,
> - * @payload.vc_start_slot will also be set to -1.
> + * Returns: 0 on success, error code on failure.
>   */
>  int drm_dp_add_payload_part1(struct drm_dp_mst_topology_mgr *mgr,
>  			     struct drm_dp_mst_topology_state *mst_state,
>  			     struct drm_dp_mst_atomic_payload *payload)
>  {
>  	struct drm_dp_mst_port *port;
> -	int ret;
> +	int ret = 0;
> +	bool allocate = true;
> +
> +	/* Update mst mgr info */
> +	if (mgr->payload_count == 0)
> +		mgr->next_start_slot = mst_state->start_slot;
> +
> +	payload->vc_start_slot = mgr->next_start_slot;
> +
> +	mgr->payload_count++;
> +	mgr->next_start_slot += payload->time_slots;
>  
> +	/* Allocate payload to immediate downstream facing port */
>  	port = drm_dp_mst_topology_get_port_validated(mgr, payload->port);
>  	if (!port) {
>  		drm_dbg_kms(mgr->dev,
> -			    "VCPI %d for port %p not in topology, not creating a payload\n",
> +			    "VCPI %d for port %p not in topology, not creating a payload to remote\n",
>  			    payload->vcpi, payload->port);
> -		payload->vc_start_slot = -1;
> -		return 0;
> +		allocate = false;
>  	}
>  
> -	if (mgr->payload_count == 0)
> -		mgr->next_start_slot = mst_state->start_slot;
> -
> -	payload->vc_start_slot = mgr->next_start_slot;
> +	if (allocate) {
> +		ret = drm_dp_create_payload_at_dfp(mgr, payload);
> +		if (ret < 0)
> +			drm_warn(mgr->dev, "Failed to create MST payload for port %p: %d\n",
> +				 payload->port, ret);
>  
> -	ret = drm_dp_create_payload_step1(mgr, payload);
> -	drm_dp_mst_topology_put_port(port);
> -	if (ret < 0) {
> -		drm_warn(mgr->dev, "Failed to create MST payload for port %p: %d\n",
> -			 payload->port, ret);
> -		payload->vc_start_slot = -1;
> -		return ret;
>  	}
>  
> -	mgr->payload_count++;
> -	mgr->next_start_slot += payload->time_slots;
> +	payload->payload_allocation_status =
> +		(!allocate || ret < 0) ? DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL :
> +								DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;

Just need to fix indenting here

>  
> -	return 0;
> +	drm_dp_mst_topology_put_port(port);
> +
> +	return ret;
>  }
>  EXPORT_SYMBOL(drm_dp_add_payload_part1);
>  
>  /**
> - * drm_dp_remove_payload() - Remove an MST payload
> + * drm_dp_remove_payload_part1() - Remove an MST payload along the virtual channel
>   * @mgr: Manager to use.
>   * @mst_state: The MST atomic state
> - * @old_payload: The payload with its old state
> - * @new_payload: The payload to write
> + * @payload: The payload to remove
>   *
> - * Removes a payload from an MST topology if it was successfully assigned a start slot. Also updates
> - * the starting time slots of all other payloads which would have been shifted towards the start of
> - * the VC table as a result. After calling this, the driver should generate ACT and payload packets.
> + * Removes a payload along the virtual channel if it was successfully allocated.
> + * After calling this, the driver should set HW to generate ACT and then switch to new
> + * payload allocation state.
>   */
> -void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
> -			   struct drm_dp_mst_topology_state *mst_state,
> -			   const struct drm_dp_mst_atomic_payload *old_payload,
> -			   struct drm_dp_mst_atomic_payload *new_payload)
> +void drm_dp_remove_payload_part1(struct drm_dp_mst_topology_mgr *mgr,
> +				 struct drm_dp_mst_topology_state *mst_state,
> +				 struct drm_dp_mst_atomic_payload *payload)
>  {
> -	struct drm_dp_mst_atomic_payload *pos;
> +	/* Remove remote payload allocation */
>  	bool send_remove = false;
>  
> -	/* We failed to make the payload, so nothing to do */
> -	if (new_payload->vc_start_slot == -1)
> -		return;
> -
>  	mutex_lock(&mgr->lock);
> -	send_remove = drm_dp_mst_port_downstream_of_branch(new_payload->port, mgr->mst_primary);
> +	send_remove = drm_dp_mst_port_downstream_of_branch(payload->port, mgr->mst_primary);
>  	mutex_unlock(&mgr->lock);
>  
>  	if (send_remove)
> -		drm_dp_destroy_payload_step1(mgr, mst_state, new_payload);
> +		drm_dp_destroy_payload_at_remote_and_dfp(mgr, mst_state, payload);
>  	else
>  		drm_dbg_kms(mgr->dev, "Payload for VCPI %d not in topology, not sending remove\n",
> -			    new_payload->vcpi);
> +			    payload->vcpi);
> +
> +	payload->payload_allocation_status = DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL;
> +}
> +EXPORT_SYMBOL(drm_dp_remove_payload_part1);
>  
> +/**
> + * drm_dp_remove_payload_part2() - Remove an MST payload locally
> + * @mgr: Manager to use.
> + * @mst_state: The MST atomic state
> + * @old_payload: The payload with its old state
> + * @new_payload: The payload with its latest state
> + *
> + * Updates the starting time slots of all other payloads which would have been shifted towards
> + * the start of the payload ID table as a result of removing a payload. Driver should call this
> + * function whenever it removes a payload in its HW. It's independent to the result of payload
> + * allocation/deallocation at branch devices along the virtual channel.
> + */
> +void drm_dp_remove_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
> +				 struct drm_dp_mst_topology_state *mst_state,
> +				 const struct drm_dp_mst_atomic_payload *old_payload,
> +				 struct drm_dp_mst_atomic_payload *new_payload)
> +{
> +	struct drm_dp_mst_atomic_payload *pos;
> +
> +	/* Remove local payload allocation */
>  	list_for_each_entry(pos, &mst_state->payloads, next) {
>  		if (pos != new_payload && pos->vc_start_slot > new_payload->vc_start_slot)
>  			pos->vc_start_slot -= old_payload->time_slots;
> @@ -3382,9 +3409,10 @@ void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
>  
>  	if (new_payload->delete)
>  		drm_dp_mst_put_port_malloc(new_payload->port);
> -}
> -EXPORT_SYMBOL(drm_dp_remove_payload);
>  
> +	new_payload->payload_allocation_status = DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
> +}
> +EXPORT_SYMBOL(drm_dp_remove_payload_part2);
>  /**
>   * drm_dp_add_payload_part2() - Execute payload update part 2
>   * @mgr: Manager to use.
> @@ -3403,17 +3431,19 @@ int drm_dp_add_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
>  	int ret = 0;
>  
>  	/* Skip failed payloads */
> -	if (payload->vc_start_slot == -1) {
> -		drm_dbg_kms(mgr->dev, "Part 1 of payload creation for %s failed, skipping part 2\n",
> +	if (payload->payload_allocation_status != DRM_DP_MST_PAYLOAD_ALLOCATION_DFP) {
> +		drm_dbg_kms(state->dev, "Part 1 of payload creation for %s failed, skipping part 2\n",
>  			    payload->port->connector->name);
>  		return -EIO;
>  	}
>  
> -	ret = drm_dp_create_payload_step2(mgr, payload);
> -	if (ret < 0) {
> +	/* Allocate payload to remote end */
> +	ret = drm_dp_create_payload_to_remote(mgr, payload);
> +	if (ret < 0)
>  		drm_err(mgr->dev, "Step 2 of creating MST payload for %p failed: %d\n",
>  			payload->port, ret);
> -	}
> +	else
> +		payload->payload_allocation_status = DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE;
>  
>  	return ret;
>  }
> @@ -4324,6 +4354,7 @@ int drm_dp_atomic_find_time_slots(struct drm_atomic_state *state,
>  		drm_dp_mst_get_port_malloc(port);
>  		payload->port = port;
>  		payload->vc_start_slot = -1;
> +		payload->payload_allocation_status = DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
>  		list_add(&payload->next, &topology_state->payloads);
>  	}
>  	payload->time_slots = req_slots;
> @@ -4493,7 +4524,7 @@ void drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state *state)
>  		}
>  
>  		/* Now that previous state is committed, it's safe to copy over the start slot
> -		 * assignments
> +		 * and allocation status assignments
>  		 */
>  		list_for_each_entry(old_payload, &old_mst_state->payloads, next) {
>  			if (old_payload->delete)
> @@ -4502,6 +4533,8 @@ void drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state *state)
>  			new_payload = drm_atomic_get_mst_payload_state(new_mst_state,
>  								       old_payload->port);
>  			new_payload->vc_start_slot = old_payload->vc_start_slot;
> +			new_payload->payload_allocation_status =
> +							old_payload->payload_allocation_status;

And here. Besides that, I think patches 1/3 and 2/3 look great! Just finished
testing them on nouveau:

Reviewed-by: Lyude Paul <lyude@redhat.com>

Patch 3/3 I gotta think about a bit more (and am curious about Imre's current
take on it) I think

>  		}
>  	}
>  }
> @@ -4818,6 +4851,13 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
>  	struct drm_dp_mst_atomic_payload *payload;
>  	int i, ret;
>  
> +	static const char *const status[] = {
> +		"None",
> +		"Local",
> +		"DFP",
> +		"Remote",
> +	};
> +
>  	mutex_lock(&mgr->lock);
>  	if (mgr->mst_primary)
>  		drm_dp_mst_dump_mstb(m, mgr->mst_primary);
> @@ -4834,7 +4874,7 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
>  	seq_printf(m, "payload_mask: %x, max_payloads: %d, start_slot: %u, pbn_div: %d\n",
>  		   state->payload_mask, mgr->max_payloads, state->start_slot, state->pbn_div);
>  
> -	seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc |     sink name     |\n");
> +	seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc | status |     sink name     |\n");
>  	for (i = 0; i < mgr->max_payloads; i++) {
>  		list_for_each_entry(payload, &state->payloads, next) {
>  			char name[14];
> @@ -4843,7 +4883,7 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
>  				continue;
>  
>  			fetch_monitor_name(mgr, payload->port, name, sizeof(name));
> -			seq_printf(m, " %5d %6d %6d %02d - %02d %5d %5s %19s\n",
> +			seq_printf(m, " %5d %6d %6d %02d - %02d %5d %5s %8s %19s\n",
>  				   i,
>  				   payload->port->port_num,
>  				   payload->vcpi,
> @@ -4851,6 +4891,7 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
>  				   payload->vc_start_slot + payload->time_slots - 1,
>  				   payload->pbn,
>  				   payload->dsc_enabled ? "Y" : "N",
> +				   status[payload->payload_allocation_status],
>  				   (*name != 0) ? name : "Unknown");
>  		}
>  	}
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> index e3f176a093d2..5f73cdabe7a1 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> @@ -557,12 +557,8 @@ static void intel_mst_disable_dp(struct intel_atomic_state *state,
>  	struct intel_dp *intel_dp = &dig_port->dp;
>  	struct intel_connector *connector =
>  		to_intel_connector(old_conn_state->connector);
> -	struct drm_dp_mst_topology_state *old_mst_state =
> -		drm_atomic_get_old_mst_topology_state(&state->base, &intel_dp->mst_mgr);
>  	struct drm_dp_mst_topology_state *new_mst_state =
>  		drm_atomic_get_new_mst_topology_state(&state->base, &intel_dp->mst_mgr);
> -	const struct drm_dp_mst_atomic_payload *old_payload =
> -		drm_atomic_get_mst_payload_state(old_mst_state, connector->port);
>  	struct drm_dp_mst_atomic_payload *new_payload =
>  		drm_atomic_get_mst_payload_state(new_mst_state, connector->port);
>  	struct drm_i915_private *i915 = to_i915(connector->base.dev);
> @@ -572,8 +568,7 @@ static void intel_mst_disable_dp(struct intel_atomic_state *state,
>  
>  	intel_hdcp_disable(intel_mst->connector);
>  
> -	drm_dp_remove_payload(&intel_dp->mst_mgr, new_mst_state,
> -			      old_payload, new_payload);
> +	drm_dp_remove_payload_part1(&intel_dp->mst_mgr, new_mst_state, new_payload);
>  
>  	intel_audio_codec_disable(encoder, old_crtc_state, old_conn_state);
>  }
> @@ -588,6 +583,14 @@ static void intel_mst_post_disable_dp(struct intel_atomic_state *state,
>  	struct intel_dp *intel_dp = &dig_port->dp;
>  	struct intel_connector *connector =
>  		to_intel_connector(old_conn_state->connector);
> +	struct drm_dp_mst_topology_state *old_mst_state =
> +		drm_atomic_get_old_mst_topology_state(&state->base, &intel_dp->mst_mgr);
> +	struct drm_dp_mst_topology_state *new_mst_state =
> +		drm_atomic_get_new_mst_topology_state(&state->base, &intel_dp->mst_mgr);
> +	const struct drm_dp_mst_atomic_payload *old_payload =
> +		drm_atomic_get_mst_payload_state(old_mst_state, connector->port);
> +	struct drm_dp_mst_atomic_payload *new_payload =
> +		drm_atomic_get_mst_payload_state(new_mst_state, connector->port);
>  	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
>  	bool last_mst_stream;
>  
> @@ -608,6 +611,9 @@ static void intel_mst_post_disable_dp(struct intel_atomic_state *state,
>  
>  	wait_for_act_sent(encoder, old_crtc_state);
>  
> +	drm_dp_remove_payload_part2(&intel_dp->mst_mgr, new_mst_state,
> +				    old_payload, new_payload);
> +
>  	intel_ddi_disable_transcoder_func(old_crtc_state);
>  
>  	if (DISPLAY_VER(dev_priv) >= 9)
> diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> index 4e7c9c353c51..bba01fa0780c 100644
> --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> @@ -882,21 +882,26 @@ struct nouveau_encoder *nv50_real_outp(struct drm_encoder *encoder)
>  
>  static void
>  nv50_msto_cleanup(struct drm_atomic_state *state,
> -		  struct drm_dp_mst_topology_state *mst_state,
> +		  struct drm_dp_mst_topology_state *new_mst_state,
>  		  struct drm_dp_mst_topology_mgr *mgr,
>  		  struct nv50_msto *msto)
>  {
>  	struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
> -	struct drm_dp_mst_atomic_payload *payload =
> -		drm_atomic_get_mst_payload_state(mst_state, msto->mstc->port);
> +	struct drm_dp_mst_atomic_payload *new_payload =
> +		drm_atomic_get_mst_payload_state(new_mst_state, msto->mstc->port);
> +	struct drm_dp_mst_topology_state *old_mst_state =
> +		drm_atomic_get_old_mst_topology_state(state, mgr);
> +	const struct drm_dp_mst_atomic_payload *old_payload =
> +		drm_atomic_get_mst_payload_state(old_mst_state, msto->mstc->port);
>  
>  	NV_ATOMIC(drm, "%s: msto cleanup\n", msto->encoder.name);
>  
>  	if (msto->disabled) {
>  		msto->mstc = NULL;
>  		msto->disabled = false;
> +		drm_dp_remove_payload_part2(mgr, new_mst_state, old_payload, new_payload);
>  	} else if (msto->enabled) {
> -		drm_dp_add_payload_part2(mgr, state, payload);
> +		drm_dp_add_payload_part2(mgr, state, new_payload);
>  		msto->enabled = false;
>  	}
>  }
> @@ -910,19 +915,15 @@ nv50_msto_prepare(struct drm_atomic_state *state,
>  	struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
>  	struct nv50_mstc *mstc = msto->mstc;
>  	struct nv50_mstm *mstm = mstc->mstm;
> -	struct drm_dp_mst_topology_state *old_mst_state;
> -	struct drm_dp_mst_atomic_payload *payload, *old_payload;
> +	struct drm_dp_mst_atomic_payload *payload;
>  
>  	NV_ATOMIC(drm, "%s: msto prepare\n", msto->encoder.name);
>  
> -	old_mst_state = drm_atomic_get_old_mst_topology_state(state, mgr);
> -
>  	payload = drm_atomic_get_mst_payload_state(mst_state, mstc->port);
> -	old_payload = drm_atomic_get_mst_payload_state(old_mst_state, mstc->port);
>  
>  	// TODO: Figure out if we want to do a better job of handling VCPI allocation failures here?
>  	if (msto->disabled) {
> -		drm_dp_remove_payload(mgr, mst_state, old_payload, payload);
> +		drm_dp_remove_payload_part1(mgr, mst_state, payload);
>  
>  		nvif_outp_dp_mst_vcpi(&mstm->outp->outp, msto->head->base.index, 0, 0, 0, 0);
>  	} else {
> diff --git a/include/drm/display/drm_dp_mst_helper.h b/include/drm/display/drm_dp_mst_helper.h
> index ed5c9660563c..4429d3b1745b 100644
> --- a/include/drm/display/drm_dp_mst_helper.h
> +++ b/include/drm/display/drm_dp_mst_helper.h
> @@ -46,6 +46,13 @@ struct drm_dp_mst_topology_ref_history {
>  };
>  #endif /* IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) */
>  
> +enum drm_dp_mst_payload_allocation {
> +	DRM_DP_MST_PAYLOAD_ALLOCATION_NONE,
> +	DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL,
> +	DRM_DP_MST_PAYLOAD_ALLOCATION_DFP,
> +	DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE,
> +};
> +
>  struct drm_dp_mst_branch;
>  
>  /**
> @@ -537,7 +544,7 @@ struct drm_dp_mst_atomic_payload {
>  	 *   drm_dp_mst_atomic_wait_for_dependencies() has been called, which will ensure the
>  	 *   previous MST states payload start slots have been copied over to the new state. Note
>  	 *   that a new start slot won't be assigned/removed from this payload until
> -	 *   drm_dp_add_payload_part1()/drm_dp_remove_payload() have been called.
> +	 *   drm_dp_add_payload_part1()/drm_dp_remove_payload_part2() have been called.
>  	 * * Acquire the MST modesetting lock, and then wait for any pending MST-related commits to
>  	 *   get committed to hardware by calling drm_crtc_commit_wait() on each of the
>  	 *   &drm_crtc_commit structs in &drm_dp_mst_topology_state.commit_deps.
> @@ -564,6 +571,9 @@ struct drm_dp_mst_atomic_payload {
>  	/** @dsc_enabled: Whether or not this payload has DSC enabled */
>  	bool dsc_enabled : 1;
>  
> +	/** @payload_allocation_status: The allocation status of this payload */
> +	enum drm_dp_mst_payload_allocation payload_allocation_status;
> +
>  	/** @next: The list node for this payload */
>  	struct list_head next;
>  };
> @@ -842,10 +852,13 @@ int drm_dp_add_payload_part1(struct drm_dp_mst_topology_mgr *mgr,
>  int drm_dp_add_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
>  			     struct drm_atomic_state *state,
>  			     struct drm_dp_mst_atomic_payload *payload);
> -void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
> -			   struct drm_dp_mst_topology_state *mst_state,
> -			   const struct drm_dp_mst_atomic_payload *old_payload,
> -			   struct drm_dp_mst_atomic_payload *new_payload);
> +void drm_dp_remove_payload_part1(struct drm_dp_mst_topology_mgr *mgr,
> +				 struct drm_dp_mst_topology_state *mst_state,
> +				 struct drm_dp_mst_atomic_payload *payload);
> +void drm_dp_remove_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
> +				 struct drm_dp_mst_topology_state *mst_state,
> +				 const struct drm_dp_mst_atomic_payload *old_payload,
> +				 struct drm_dp_mst_atomic_payload *new_payload);
>  
>  int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr);
>  

-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat

RE: [Patch v2 2/3] drm/mst: Refactor the flow for payload allocation/removement

[Lin, Wayne]

[Public]

Thanks, Lyude!
Should I push another version to fix the indention?

> -----Original Message-----
> From: Lyude Paul <lyude@redhat.com>
> Sent: Friday, August 18, 2023 6:17 AM
> To: Lin, Wayne <Wayne.Lin@amd.com>; dri-devel@lists.freedesktop.org;
> amd-gfx@lists.freedesktop.org
> Cc: jani.nikula@intel.com; ville.syrjala@linux.intel.com; imre.deak@intel.com;
> Wentland, Harry <Harry.Wentland@amd.com>; Zuo, Jerry
> <Jerry.Zuo@amd.com>
> Subject: Re: [Patch v2 2/3] drm/mst: Refactor the flow for payload
> allocation/removement
>
> Two small comments:
>
> On Mon, 2023-08-07 at 10:56 +0800, Wayne Lin wrote:
> > [Why]
> > Today, the allocation/deallocation steps and status is a bit unclear.
> >
> > For instance, payload->vc_start_slot = -1 stands for "the failure of
> > updating DPCD payload ID table" and can also represent as "payload is
> > not allocated yet". These two cases should be handled differently and
> > hence better to distinguish them for better understanding.
> >
> > [How]
> > Define enumeration - ALLOCATION_LOCAL, ALLOCATION_DFP and
> > ALLOCATION_REMOTE to distinguish different allocation status. Adjust
> > the code to handle different status accordingly for better
> > understanding the sequence of payload allocation and payload
> removement.
> >
> > For payload creation, the procedure should look like this:
> > DRM part 1:
> > * step 1 - update sw mst mgr variables to add a new payload
> > * step 2 - add payload at immediate DFP DPCD payload table
> >
> > Driver:
> > * Add new payload in HW and sync up with DFP by sending ACT
> >
> > DRM Part 2:
> > * Send ALLOCATE_PAYLOAD sideband message to allocate bandwidth along
> the
> >   virtual channel.
> >
> > And as for payload removement, the procedure should look like this:
> > DRM part 1:
> > * step 1 - Send ALLOCATE_PAYLOAD sideband message to release bandwidth
> >            along the virtual channel
> > * step 2 - Clear payload allocation at immediate DFP DPCD payload
> > table
> >
> > Driver:
> > * Remove the payload in HW and sync up with DFP by sending ACT
> >
> > DRM part 2:
> > * update sw mst mgr variables to remove the payload
> >
> > Note that it's fine to fail when communicate with the branch device
> > connected at immediate downstrean-facing port, but updating variables
> > of SW mst mgr and HW configuration should be conducted anyway. That's
> > because it's under commit_tail and we need to complete the HW
> programming.
> >
> > Changes since v1:
> > * Remove the set but not use variable 'old_payload' in function
> >   'nv50_msto_prepare'. Catched by kernel test robot <lkp@intel.com>
> >
> > Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
> > ---
> >  .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  20 ++-
> > drivers/gpu/drm/display/drm_dp_mst_topology.c | 159 +++++++++++------
> -
> >  drivers/gpu/drm/i915/display/intel_dp_mst.c   |  18 +-
> >  drivers/gpu/drm/nouveau/dispnv50/disp.c       |  21 +--
> >  include/drm/display/drm_dp_mst_helper.h       |  23 ++-
> >  5 files changed, 153 insertions(+), 88 deletions(-)
> >
> > diff --git
> a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > index d9a482908380..9ad509279b0a 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > @@ -219,7 +219,7 @@ static void dm_helpers_construct_old_payload(
> >     /* Set correct time_slots/PBN of old payload.
> >      * other fields (delete & dsc_enabled) in
> >      * struct drm_dp_mst_atomic_payload are don't care fields
> > -    * while calling drm_dp_remove_payload()
> > +    * while calling drm_dp_remove_payload_part2()
> >      */
> >     for (i = 0; i < current_link_table.stream_count; i++) {
> >             dc_alloc =
> > @@ -262,13 +262,12 @@ bool
> > dm_helpers_dp_mst_write_payload_allocation_table(
> >
> >     mst_mgr = &aconnector->mst_root->mst_mgr;
> >     mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
> > -
> > -   /* It's OK for this to fail */
> >     new_payload = drm_atomic_get_mst_payload_state(mst_state,
> > aconnector->mst_output_port);
> >
> >     if (enable) {
> >             target_payload = new_payload;
> >
> > +           /* It's OK for this to fail */
> >             drm_dp_add_payload_part1(mst_mgr, mst_state,
> new_payload);
> >     } else {
> >             /* construct old payload by VCPI*/
> > @@ -276,7 +275,7 @@ bool
> dm_helpers_dp_mst_write_payload_allocation_table(
> >                                             new_payload, &old_payload);
> >             target_payload = &old_payload;
> >
> > -           drm_dp_remove_payload(mst_mgr, mst_state,
> &old_payload, new_payload);
> > +           drm_dp_remove_payload_part1(mst_mgr, mst_state,
> new_payload);
> >     }
> >
> >     /* mst_mgr->->payloads are VC payload notify MST branch using
> DPCD
> > or @@ -342,7 +341,7 @@ bool
> dm_helpers_dp_mst_send_payload_allocation(
> >     struct amdgpu_dm_connector *aconnector;
> >     struct drm_dp_mst_topology_state *mst_state;
> >     struct drm_dp_mst_topology_mgr *mst_mgr;
> > -   struct drm_dp_mst_atomic_payload *payload;
> > +   struct drm_dp_mst_atomic_payload *new_payload, *old_payload;
> >     enum mst_progress_status set_flag =
> MST_ALLOCATE_NEW_PAYLOAD;
> >     enum mst_progress_status clr_flag =
> MST_CLEAR_ALLOCATED_PAYLOAD;
> >     int ret = 0;
> > @@ -355,15 +354,20 @@ bool
> dm_helpers_dp_mst_send_payload_allocation(
> >     mst_mgr = &aconnector->mst_root->mst_mgr;
> >     mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
> >
> > -   payload = drm_atomic_get_mst_payload_state(mst_state,
> aconnector->mst_output_port);
> > +   new_payload = drm_atomic_get_mst_payload_state(mst_state,
> > +aconnector->mst_output_port);
> >
> >     if (!enable) {
> >             set_flag = MST_CLEAR_ALLOCATED_PAYLOAD;
> >             clr_flag = MST_ALLOCATE_NEW_PAYLOAD;
> >     }
> >
> > -   if (enable)
> > -           ret = drm_dp_add_payload_part2(mst_mgr, mst_state-
> >base.state, payload);
> > +   if (enable) {
> > +           ret = drm_dp_add_payload_part2(mst_mgr, mst_state-
> >base.state, new_payload);
> > +   } else {
> > +           dm_helpers_construct_old_payload(stream->link, mst_state-
> >pbn_div,
> > +                                            new_payload, old_payload);
> > +           drm_dp_remove_payload_part2(mst_mgr, mst_state,
> old_payload, new_payload);
> > +   }
> >
> >     if (ret) {
> >             amdgpu_dm_set_mst_status(&aconnector->mst_status,
> > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > index 4d80426757ab..e04f87ff755a 100644
> > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > @@ -3255,15 +3255,15 @@ int
> drm_dp_send_query_stream_enc_status(struct
> > drm_dp_mst_topology_mgr *mgr,  }
> > EXPORT_SYMBOL(drm_dp_send_query_stream_enc_status);
> >
> > -static int drm_dp_create_payload_step1(struct drm_dp_mst_topology_mgr
> *mgr,
> > -                                  struct drm_dp_mst_atomic_payload
> *payload)
> > +static int drm_dp_create_payload_at_dfp(struct
> drm_dp_mst_topology_mgr *mgr,
> > +                                   struct drm_dp_mst_atomic_payload
> *payload)
> >  {
> >     return drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload-
> >vc_start_slot,
> >                                      payload->time_slots);
> >  }
> >
> > -static int drm_dp_create_payload_step2(struct drm_dp_mst_topology_mgr
> *mgr,
> > -                                  struct drm_dp_mst_atomic_payload
> *payload)
> > +static int drm_dp_create_payload_to_remote(struct
> drm_dp_mst_topology_mgr *mgr,
> > +                                      struct drm_dp_mst_atomic_payload
> *payload)
> >  {
> >     int ret;
> >     struct drm_dp_mst_port *port =
> > drm_dp_mst_topology_get_port_validated(mgr, payload->port); @@ -
> 3276,17 +3276,20 @@ static int drm_dp_create_payload_step2(struct
> drm_dp_mst_topology_mgr *mgr,
> >     return ret;
> >  }
> >
> > -static int drm_dp_destroy_payload_step1(struct
> drm_dp_mst_topology_mgr *mgr,
> > -                                   struct drm_dp_mst_topology_state
> *mst_state,
> > -                                   struct drm_dp_mst_atomic_payload
> *payload)
> > +static void drm_dp_destroy_payload_at_remote_and_dfp(struct
> drm_dp_mst_topology_mgr *mgr,
> > +                                                struct
> drm_dp_mst_topology_state *mst_state,
> > +                                                struct
> drm_dp_mst_atomic_payload *payload)
> >  {
> >     drm_dbg_kms(mgr->dev, "\n");
> >
> >     /* it's okay for these to fail */
> > -   drm_dp_payload_send_msg(mgr, payload->port, payload->vcpi, 0);
> > -   drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload-
> >vc_start_slot, 0);
> > +   if (payload->payload_allocation_status ==
> DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE) {
> > +           drm_dp_payload_send_msg(mgr, payload->port, payload-
> >vcpi, 0);
> > +           payload->payload_allocation_status =
> DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
> > +   }
> >
> > -   return 0;
> > +   if (payload->payload_allocation_status ==
> DRM_DP_MST_PAYLOAD_ALLOCATION_DFP)
> > +           drm_dp_dpcd_write_payload(mgr, payload->vcpi,
> > +payload->vc_start_slot, 0);
> >  }
> >
> >  /**
> > @@ -3296,81 +3299,105 @@ static int
> drm_dp_destroy_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
> >   * @payload: The payload to write
> >   *
> >   * Determines the starting time slot for the given payload, and
> > programs the VCPI for this payload
> > - * into hardware. After calling this, the driver should generate ACT and
> payload packets.
> > + * into the DPCD of DPRX. After calling this, the driver should generate ACT
> and payload packets.
> >   *
> > - * Returns: 0 on success, error code on failure. In the event that
> > this fails,
> > - * @payload.vc_start_slot will also be set to -1.
> > + * Returns: 0 on success, error code on failure.
> >   */
> >  int drm_dp_add_payload_part1(struct drm_dp_mst_topology_mgr *mgr,
> >                          struct drm_dp_mst_topology_state *mst_state,
> >                          struct drm_dp_mst_atomic_payload *payload)  {
> >     struct drm_dp_mst_port *port;
> > -   int ret;
> > +   int ret = 0;
> > +   bool allocate = true;
> > +
> > +   /* Update mst mgr info */
> > +   if (mgr->payload_count == 0)
> > +           mgr->next_start_slot = mst_state->start_slot;
> > +
> > +   payload->vc_start_slot = mgr->next_start_slot;
> > +
> > +   mgr->payload_count++;
> > +   mgr->next_start_slot += payload->time_slots;
> >
> > +   /* Allocate payload to immediate downstream facing port */
> >     port = drm_dp_mst_topology_get_port_validated(mgr, payload-
> >port);
> >     if (!port) {
> >             drm_dbg_kms(mgr->dev,
> > -                       "VCPI %d for port %p not in topology, not creating a
> payload\n",
> > +                       "VCPI %d for port %p not in topology, not creating a
> payload
> > +to remote\n",
> >                         payload->vcpi, payload->port);
> > -           payload->vc_start_slot = -1;
> > -           return 0;
> > +           allocate = false;
> >     }
> >
> > -   if (mgr->payload_count == 0)
> > -           mgr->next_start_slot = mst_state->start_slot;
> > -
> > -   payload->vc_start_slot = mgr->next_start_slot;
> > +   if (allocate) {
> > +           ret = drm_dp_create_payload_at_dfp(mgr, payload);
> > +           if (ret < 0)
> > +                   drm_warn(mgr->dev, "Failed to create MST payload
> for port %p: %d\n",
> > +                            payload->port, ret);
> >
> > -   ret = drm_dp_create_payload_step1(mgr, payload);
> > -   drm_dp_mst_topology_put_port(port);
> > -   if (ret < 0) {
> > -           drm_warn(mgr->dev, "Failed to create MST payload for port
> %p: %d\n",
> > -                    payload->port, ret);
> > -           payload->vc_start_slot = -1;
> > -           return ret;
> >     }
> >
> > -   mgr->payload_count++;
> > -   mgr->next_start_slot += payload->time_slots;
> > +   payload->payload_allocation_status =
> > +           (!allocate || ret < 0) ?
> DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL :
> > +
>       DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
>
> Just need to fix indenting here
>
> >
> > -   return 0;
> > +   drm_dp_mst_topology_put_port(port);
> > +
> > +   return ret;
> >  }
> >  EXPORT_SYMBOL(drm_dp_add_payload_part1);
> >
> >  /**
> > - * drm_dp_remove_payload() - Remove an MST payload
> > + * drm_dp_remove_payload_part1() - Remove an MST payload along the
> > + virtual channel
> >   * @mgr: Manager to use.
> >   * @mst_state: The MST atomic state
> > - * @old_payload: The payload with its old state
> > - * @new_payload: The payload to write
> > + * @payload: The payload to remove
> >   *
> > - * Removes a payload from an MST topology if it was successfully
> > assigned a start slot. Also updates
> > - * the starting time slots of all other payloads which would have
> > been shifted towards the start of
> > - * the VC table as a result. After calling this, the driver should generate ACT
> and payload packets.
> > + * Removes a payload along the virtual channel if it was successfully
> allocated.
> > + * After calling this, the driver should set HW to generate ACT and
> > + then switch to new
> > + * payload allocation state.
> >   */
> > -void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
> > -                      struct drm_dp_mst_topology_state *mst_state,
> > -                      const struct drm_dp_mst_atomic_payload
> *old_payload,
> > -                      struct drm_dp_mst_atomic_payload *new_payload)
> > +void drm_dp_remove_payload_part1(struct drm_dp_mst_topology_mgr
> *mgr,
> > +                            struct drm_dp_mst_topology_state
> *mst_state,
> > +                            struct drm_dp_mst_atomic_payload
> *payload)
> >  {
> > -   struct drm_dp_mst_atomic_payload *pos;
> > +   /* Remove remote payload allocation */
> >     bool send_remove = false;
> >
> > -   /* We failed to make the payload, so nothing to do */
> > -   if (new_payload->vc_start_slot == -1)
> > -           return;
> > -
> >     mutex_lock(&mgr->lock);
> > -   send_remove =
> drm_dp_mst_port_downstream_of_branch(new_payload->port, mgr-
> >mst_primary);
> > +   send_remove = drm_dp_mst_port_downstream_of_branch(payload-
> >port,
> > +mgr->mst_primary);
> >     mutex_unlock(&mgr->lock);
> >
> >     if (send_remove)
> > -           drm_dp_destroy_payload_step1(mgr, mst_state,
> new_payload);
> > +           drm_dp_destroy_payload_at_remote_and_dfp(mgr,
> mst_state, payload);
> >     else
> >             drm_dbg_kms(mgr->dev, "Payload for VCPI %d not in
> topology, not sending remove\n",
> > -                       new_payload->vcpi);
> > +                       payload->vcpi);
> > +
> > +   payload->payload_allocation_status =
> > +DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL;
> > +}
> > +EXPORT_SYMBOL(drm_dp_remove_payload_part1);
> >
> > +/**
> > + * drm_dp_remove_payload_part2() - Remove an MST payload locally
> > + * @mgr: Manager to use.
> > + * @mst_state: The MST atomic state
> > + * @old_payload: The payload with its old state
> > + * @new_payload: The payload with its latest state
> > + *
> > + * Updates the starting time slots of all other payloads which would
> > +have been shifted towards
> > + * the start of the payload ID table as a result of removing a
> > +payload. Driver should call this
> > + * function whenever it removes a payload in its HW. It's independent
> > +to the result of payload
> > + * allocation/deallocation at branch devices along the virtual channel.
> > + */
> > +void drm_dp_remove_payload_part2(struct drm_dp_mst_topology_mgr
> *mgr,
> > +                            struct drm_dp_mst_topology_state
> *mst_state,
> > +                            const struct drm_dp_mst_atomic_payload
> *old_payload,
> > +                            struct drm_dp_mst_atomic_payload
> *new_payload) {
> > +   struct drm_dp_mst_atomic_payload *pos;
> > +
> > +   /* Remove local payload allocation */
> >     list_for_each_entry(pos, &mst_state->payloads, next) {
> >             if (pos != new_payload && pos->vc_start_slot > new_payload-
> >vc_start_slot)
> >                     pos->vc_start_slot -= old_payload->time_slots; @@ -
> 3382,9 +3409,10
> > @@ void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr
> *mgr,
> >
> >     if (new_payload->delete)
> >             drm_dp_mst_put_port_malloc(new_payload->port);
> > -}
> > -EXPORT_SYMBOL(drm_dp_remove_payload);
> >
> > +   new_payload->payload_allocation_status =
> > +DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
> > +}
> > +EXPORT_SYMBOL(drm_dp_remove_payload_part2);
> >  /**
> >   * drm_dp_add_payload_part2() - Execute payload update part 2
> >   * @mgr: Manager to use.
> > @@ -3403,17 +3431,19 @@ int drm_dp_add_payload_part2(struct
> drm_dp_mst_topology_mgr *mgr,
> >     int ret = 0;
> >
> >     /* Skip failed payloads */
> > -   if (payload->vc_start_slot == -1) {
> > -           drm_dbg_kms(mgr->dev, "Part 1 of payload creation for %s
> failed, skipping part 2\n",
> > +   if (payload->payload_allocation_status !=
> DRM_DP_MST_PAYLOAD_ALLOCATION_DFP) {
> > +           drm_dbg_kms(state->dev, "Part 1 of payload creation for %s
> failed,
> > +skipping part 2\n",
> >                         payload->port->connector->name);
> >             return -EIO;
> >     }
> >
> > -   ret = drm_dp_create_payload_step2(mgr, payload);
> > -   if (ret < 0) {
> > +   /* Allocate payload to remote end */
> > +   ret = drm_dp_create_payload_to_remote(mgr, payload);
> > +   if (ret < 0)
> >             drm_err(mgr->dev, "Step 2 of creating MST payload for %p
> failed: %d\n",
> >                     payload->port, ret);
> > -   }
> > +   else
> > +           payload->payload_allocation_status =
> > +DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE;
> >
> >     return ret;
> >  }
> > @@ -4324,6 +4354,7 @@ int drm_dp_atomic_find_time_slots(struct
> drm_atomic_state *state,
> >             drm_dp_mst_get_port_malloc(port);
> >             payload->port = port;
> >             payload->vc_start_slot = -1;
> > +           payload->payload_allocation_status =
> > +DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
> >             list_add(&payload->next, &topology_state->payloads);
> >     }
> >     payload->time_slots = req_slots;
> > @@ -4493,7 +4524,7 @@ void
> drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state
> *state)
> >             }
> >
> >             /* Now that previous state is committed, it's safe to copy over
> the start slot
> > -            * assignments
> > +            * and allocation status assignments
> >              */
> >             list_for_each_entry(old_payload, &old_mst_state->payloads,
> next) {
> >                     if (old_payload->delete)
> > @@ -4502,6 +4533,8 @@ void
> drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state
> *state)
> >                     new_payload =
> drm_atomic_get_mst_payload_state(new_mst_state,
> >
> old_payload->port);
> >                     new_payload->vc_start_slot = old_payload-
> >vc_start_slot;
> > +                   new_payload->payload_allocation_status =
> > +                                                   old_payload-
> >payload_allocation_status;
>
> And here. Besides that, I think patches 1/3 and 2/3 look great! Just finished
> testing them on nouveau:
>
> Reviewed-by: Lyude Paul <lyude@redhat.com>
>
> Patch 3/3 I gotta think about a bit more (and am curious about Imre's current
> take on it) I think
>
> >             }
> >     }
> >  }
> > @@ -4818,6 +4851,13 @@ void drm_dp_mst_dump_topology(struct
> seq_file *m,
> >     struct drm_dp_mst_atomic_payload *payload;
> >     int i, ret;
> >
> > +   static const char *const status[] = {
> > +           "None",
> > +           "Local",
> > +           "DFP",
> > +           "Remote",
> > +   };
> > +
> >     mutex_lock(&mgr->lock);
> >     if (mgr->mst_primary)
> >             drm_dp_mst_dump_mstb(m, mgr->mst_primary); @@ -
> 4834,7 +4874,7 @@
> > void drm_dp_mst_dump_topology(struct seq_file *m,
> >     seq_printf(m, "payload_mask: %x, max_payloads: %d, start_slot: %u,
> pbn_div: %d\n",
> >                state->payload_mask, mgr->max_payloads, state-
> >start_slot,
> > state->pbn_div);
> >
> > -   seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc |     sink name
> |\n");
> > +   seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc | status |     sink
> name     |\n");
> >     for (i = 0; i < mgr->max_payloads; i++) {
> >             list_for_each_entry(payload, &state->payloads, next) {
> >                     char name[14];
> > @@ -4843,7 +4883,7 @@ void drm_dp_mst_dump_topology(struct
> seq_file *m,
> >                             continue;
> >
> >                     fetch_monitor_name(mgr, payload->port, name,
> sizeof(name));
> > -                   seq_printf(m, " %5d %6d %6d %02d - %02d %5d %5s
> %19s\n",
> > +                   seq_printf(m, " %5d %6d %6d %02d - %02d %5d %5s
> %8s %19s\n",
> >                                i,
> >                                payload->port->port_num,
> >                                payload->vcpi,
> > @@ -4851,6 +4891,7 @@ void drm_dp_mst_dump_topology(struct
> seq_file *m,
> >                                payload->vc_start_slot + payload-
> >time_slots - 1,
> >                                payload->pbn,
> >                                payload->dsc_enabled ? "Y" : "N",
> > +                              status[payload->payload_allocation_status],
> >                                (*name != 0) ? name : "Unknown");
> >             }
> >     }
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > index e3f176a093d2..5f73cdabe7a1 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > @@ -557,12 +557,8 @@ static void intel_mst_disable_dp(struct
> intel_atomic_state *state,
> >     struct intel_dp *intel_dp = &dig_port->dp;
> >     struct intel_connector *connector =
> >             to_intel_connector(old_conn_state->connector);
> > -   struct drm_dp_mst_topology_state *old_mst_state =
> > -           drm_atomic_get_old_mst_topology_state(&state->base,
> &intel_dp->mst_mgr);
> >     struct drm_dp_mst_topology_state *new_mst_state =
> >             drm_atomic_get_new_mst_topology_state(&state->base,
> &intel_dp->mst_mgr);
> > -   const struct drm_dp_mst_atomic_payload *old_payload =
> > -           drm_atomic_get_mst_payload_state(old_mst_state,
> connector->port);
> >     struct drm_dp_mst_atomic_payload *new_payload =
> >             drm_atomic_get_mst_payload_state(new_mst_state,
> connector->port);
> >     struct drm_i915_private *i915 = to_i915(connector->base.dev); @@
> > -572,8 +568,7 @@ static void intel_mst_disable_dp(struct
> > intel_atomic_state *state,
> >
> >     intel_hdcp_disable(intel_mst->connector);
> >
> > -   drm_dp_remove_payload(&intel_dp->mst_mgr, new_mst_state,
> > -                         old_payload, new_payload);
> > +   drm_dp_remove_payload_part1(&intel_dp->mst_mgr,
> new_mst_state,
> > +new_payload);
> >
> >     intel_audio_codec_disable(encoder, old_crtc_state, old_conn_state);
> > } @@ -588,6 +583,14 @@ static void intel_mst_post_disable_dp(struct
> > intel_atomic_state *state,
> >     struct intel_dp *intel_dp = &dig_port->dp;
> >     struct intel_connector *connector =
> >             to_intel_connector(old_conn_state->connector);
> > +   struct drm_dp_mst_topology_state *old_mst_state =
> > +           drm_atomic_get_old_mst_topology_state(&state->base,
> &intel_dp->mst_mgr);
> > +   struct drm_dp_mst_topology_state *new_mst_state =
> > +           drm_atomic_get_new_mst_topology_state(&state->base,
> &intel_dp->mst_mgr);
> > +   const struct drm_dp_mst_atomic_payload *old_payload =
> > +           drm_atomic_get_mst_payload_state(old_mst_state,
> connector->port);
> > +   struct drm_dp_mst_atomic_payload *new_payload =
> > +           drm_atomic_get_mst_payload_state(new_mst_state,
> connector->port);
> >     struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
> >     bool last_mst_stream;
> >
> > @@ -608,6 +611,9 @@ static void intel_mst_post_disable_dp(struct
> > intel_atomic_state *state,
> >
> >     wait_for_act_sent(encoder, old_crtc_state);
> >
> > +   drm_dp_remove_payload_part2(&intel_dp->mst_mgr,
> new_mst_state,
> > +                               old_payload, new_payload);
> > +
> >     intel_ddi_disable_transcoder_func(old_crtc_state);
> >
> >     if (DISPLAY_VER(dev_priv) >= 9)
> > diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > index 4e7c9c353c51..bba01fa0780c 100644
> > --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > @@ -882,21 +882,26 @@ struct nouveau_encoder *nv50_real_outp(struct
> > drm_encoder *encoder)
> >
> >  static void
> >  nv50_msto_cleanup(struct drm_atomic_state *state,
> > -             struct drm_dp_mst_topology_state *mst_state,
> > +             struct drm_dp_mst_topology_state *new_mst_state,
> >               struct drm_dp_mst_topology_mgr *mgr,
> >               struct nv50_msto *msto)
> >  {
> >     struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
> > -   struct drm_dp_mst_atomic_payload *payload =
> > -           drm_atomic_get_mst_payload_state(mst_state, msto->mstc-
> >port);
> > +   struct drm_dp_mst_atomic_payload *new_payload =
> > +           drm_atomic_get_mst_payload_state(new_mst_state, msto-
> >mstc->port);
> > +   struct drm_dp_mst_topology_state *old_mst_state =
> > +           drm_atomic_get_old_mst_topology_state(state, mgr);
> > +   const struct drm_dp_mst_atomic_payload *old_payload =
> > +           drm_atomic_get_mst_payload_state(old_mst_state, msto-
> >mstc->port);
> >
> >     NV_ATOMIC(drm, "%s: msto cleanup\n", msto->encoder.name);
> >
> >     if (msto->disabled) {
> >             msto->mstc = NULL;
> >             msto->disabled = false;
> > +           drm_dp_remove_payload_part2(mgr, new_mst_state,
> old_payload,
> > +new_payload);
> >     } else if (msto->enabled) {
> > -           drm_dp_add_payload_part2(mgr, state, payload);
> > +           drm_dp_add_payload_part2(mgr, state, new_payload);
> >             msto->enabled = false;
> >     }
> >  }
> > @@ -910,19 +915,15 @@ nv50_msto_prepare(struct drm_atomic_state
> *state,
> >     struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
> >     struct nv50_mstc *mstc = msto->mstc;
> >     struct nv50_mstm *mstm = mstc->mstm;
> > -   struct drm_dp_mst_topology_state *old_mst_state;
> > -   struct drm_dp_mst_atomic_payload *payload, *old_payload;
> > +   struct drm_dp_mst_atomic_payload *payload;
> >
> >     NV_ATOMIC(drm, "%s: msto prepare\n", msto->encoder.name);
> >
> > -   old_mst_state = drm_atomic_get_old_mst_topology_state(state,
> mgr);
> > -
> >     payload = drm_atomic_get_mst_payload_state(mst_state, mstc-
> >port);
> > -   old_payload = drm_atomic_get_mst_payload_state(old_mst_state,
> mstc->port);
> >
> >     // TODO: Figure out if we want to do a better job of handling VCPI
> allocation failures here?
> >     if (msto->disabled) {
> > -           drm_dp_remove_payload(mgr, mst_state, old_payload,
> payload);
> > +           drm_dp_remove_payload_part1(mgr, mst_state, payload);
> >
> >             nvif_outp_dp_mst_vcpi(&mstm->outp->outp, msto->head-
> >base.index, 0, 0, 0, 0);
> >     } else {
> > diff --git a/include/drm/display/drm_dp_mst_helper.h
> > b/include/drm/display/drm_dp_mst_helper.h
> > index ed5c9660563c..4429d3b1745b 100644
> > --- a/include/drm/display/drm_dp_mst_helper.h
> > +++ b/include/drm/display/drm_dp_mst_helper.h
> > @@ -46,6 +46,13 @@ struct drm_dp_mst_topology_ref_history {  };
> > #endif /* IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) */
> >
> > +enum drm_dp_mst_payload_allocation {
> > +   DRM_DP_MST_PAYLOAD_ALLOCATION_NONE,
> > +   DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL,
> > +   DRM_DP_MST_PAYLOAD_ALLOCATION_DFP,
> > +   DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE,
> > +};
> > +
> >  struct drm_dp_mst_branch;
> >
> >  /**
> > @@ -537,7 +544,7 @@ struct drm_dp_mst_atomic_payload {
> >      *   drm_dp_mst_atomic_wait_for_dependencies() has been called,
> which will ensure the
> >      *   previous MST states payload start slots have been copied over to
> the new state. Note
> >      *   that a new start slot won't be assigned/removed from this payload
> until
> > -    *   drm_dp_add_payload_part1()/drm_dp_remove_payload() have
> been called.
> > +    *   drm_dp_add_payload_part1()/drm_dp_remove_payload_part2()
> have been called.
> >      * * Acquire the MST modesetting lock, and then wait for any pending
> MST-related commits to
> >      *   get committed to hardware by calling drm_crtc_commit_wait() on
> each of the
> >      *   &drm_crtc_commit structs in
> &drm_dp_mst_topology_state.commit_deps.
> > @@ -564,6 +571,9 @@ struct drm_dp_mst_atomic_payload {
> >     /** @dsc_enabled: Whether or not this payload has DSC enabled */
> >     bool dsc_enabled : 1;
> >
> > +   /** @payload_allocation_status: The allocation status of this payload
> */
> > +   enum drm_dp_mst_payload_allocation payload_allocation_status;
> > +
> >     /** @next: The list node for this payload */
> >     struct list_head next;
> >  };
> > @@ -842,10 +852,13 @@ int drm_dp_add_payload_part1(struct
> > drm_dp_mst_topology_mgr *mgr,  int drm_dp_add_payload_part2(struct
> drm_dp_mst_topology_mgr *mgr,
> >                          struct drm_atomic_state *state,
> >                          struct drm_dp_mst_atomic_payload *payload); -
> void
> > drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
> > -                      struct drm_dp_mst_topology_state *mst_state,
> > -                      const struct drm_dp_mst_atomic_payload
> *old_payload,
> > -                      struct drm_dp_mst_atomic_payload
> *new_payload);
> > +void drm_dp_remove_payload_part1(struct drm_dp_mst_topology_mgr
> *mgr,
> > +                            struct drm_dp_mst_topology_state
> *mst_state,
> > +                            struct drm_dp_mst_atomic_payload
> *payload); void
> > +drm_dp_remove_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
> > +                            struct drm_dp_mst_topology_state
> *mst_state,
> > +                            const struct drm_dp_mst_atomic_payload
> *old_payload,
> > +                            struct drm_dp_mst_atomic_payload
> *new_payload);
> >
> >  int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr);
> >
>
> --
> Cheers,
>  Lyude Paul (she/her)
>  Software Engineer at Red Hat
--
Regards,
Wayne

Re: [Patch v2 2/3] drm/mst: Refactor the flow for payload allocation/removement

[Lyude Paul]

Sure - you're also welcome to push the first two patches after fixing the
indentation if you'd like

On Wed, 2023-08-23 at 03:19 +0000, Lin, Wayne wrote:
> [Public]
> 
> Thanks, Lyude!
> Should I push another version to fix the indention?
> 
> > -----Original Message-----
> > From: Lyude Paul <lyude@redhat.com>
> > Sent: Friday, August 18, 2023 6:17 AM
> > To: Lin, Wayne <Wayne.Lin@amd.com>; dri-devel@lists.freedesktop.org;
> > amd-gfx@lists.freedesktop.org
> > Cc: jani.nikula@intel.com; ville.syrjala@linux.intel.com; imre.deak@intel.com;
> > Wentland, Harry <Harry.Wentland@amd.com>; Zuo, Jerry
> > <Jerry.Zuo@amd.com>
> > Subject: Re: [Patch v2 2/3] drm/mst: Refactor the flow for payload
> > allocation/removement
> > 
> > Two small comments:
> > 
> > On Mon, 2023-08-07 at 10:56 +0800, Wayne Lin wrote:
> > > [Why]
> > > Today, the allocation/deallocation steps and status is a bit unclear.
> > > 
> > > For instance, payload->vc_start_slot = -1 stands for "the failure of
> > > updating DPCD payload ID table" and can also represent as "payload is
> > > not allocated yet". These two cases should be handled differently and
> > > hence better to distinguish them for better understanding.
> > > 
> > > [How]
> > > Define enumeration - ALLOCATION_LOCAL, ALLOCATION_DFP and
> > > ALLOCATION_REMOTE to distinguish different allocation status. Adjust
> > > the code to handle different status accordingly for better
> > > understanding the sequence of payload allocation and payload
> > removement.
> > > 
> > > For payload creation, the procedure should look like this:
> > > DRM part 1:
> > > * step 1 - update sw mst mgr variables to add a new payload
> > > * step 2 - add payload at immediate DFP DPCD payload table
> > > 
> > > Driver:
> > > * Add new payload in HW and sync up with DFP by sending ACT
> > > 
> > > DRM Part 2:
> > > * Send ALLOCATE_PAYLOAD sideband message to allocate bandwidth along
> > the
> > >   virtual channel.
> > > 
> > > And as for payload removement, the procedure should look like this:
> > > DRM part 1:
> > > * step 1 - Send ALLOCATE_PAYLOAD sideband message to release bandwidth
> > >            along the virtual channel
> > > * step 2 - Clear payload allocation at immediate DFP DPCD payload
> > > table
> > > 
> > > Driver:
> > > * Remove the payload in HW and sync up with DFP by sending ACT
> > > 
> > > DRM part 2:
> > > * update sw mst mgr variables to remove the payload
> > > 
> > > Note that it's fine to fail when communicate with the branch device
> > > connected at immediate downstrean-facing port, but updating variables
> > > of SW mst mgr and HW configuration should be conducted anyway. That's
> > > because it's under commit_tail and we need to complete the HW
> > programming.
> > > 
> > > Changes since v1:
> > > * Remove the set but not use variable 'old_payload' in function
> > >   'nv50_msto_prepare'. Catched by kernel test robot <lkp@intel.com>
> > > 
> > > Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
> > > ---
> > >  .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  20 ++-
> > > drivers/gpu/drm/display/drm_dp_mst_topology.c | 159 +++++++++++------
> > -
> > >  drivers/gpu/drm/i915/display/intel_dp_mst.c   |  18 +-
> > >  drivers/gpu/drm/nouveau/dispnv50/disp.c       |  21 +--
> > >  include/drm/display/drm_dp_mst_helper.h       |  23 ++-
> > >  5 files changed, 153 insertions(+), 88 deletions(-)
> > > 
> > > diff --git
> > a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > index d9a482908380..9ad509279b0a 100644
> > > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > @@ -219,7 +219,7 @@ static void dm_helpers_construct_old_payload(
> > >     /* Set correct time_slots/PBN of old payload.
> > >      * other fields (delete & dsc_enabled) in
> > >      * struct drm_dp_mst_atomic_payload are don't care fields
> > > -    * while calling drm_dp_remove_payload()
> > > +    * while calling drm_dp_remove_payload_part2()
> > >      */
> > >     for (i = 0; i < current_link_table.stream_count; i++) {
> > >             dc_alloc =
> > > @@ -262,13 +262,12 @@ bool
> > > dm_helpers_dp_mst_write_payload_allocation_table(
> > > 
> > >     mst_mgr = &aconnector->mst_root->mst_mgr;
> > >     mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
> > > -
> > > -   /* It's OK for this to fail */
> > >     new_payload = drm_atomic_get_mst_payload_state(mst_state,
> > > aconnector->mst_output_port);
> > > 
> > >     if (enable) {
> > >             target_payload = new_payload;
> > > 
> > > +           /* It's OK for this to fail */
> > >             drm_dp_add_payload_part1(mst_mgr, mst_state,
> > new_payload);
> > >     } else {
> > >             /* construct old payload by VCPI*/
> > > @@ -276,7 +275,7 @@ bool
> > dm_helpers_dp_mst_write_payload_allocation_table(
> > >                                             new_payload, &old_payload);
> > >             target_payload = &old_payload;
> > > 
> > > -           drm_dp_remove_payload(mst_mgr, mst_state,
> > &old_payload, new_payload);
> > > +           drm_dp_remove_payload_part1(mst_mgr, mst_state,
> > new_payload);
> > >     }
> > > 
> > >     /* mst_mgr->->payloads are VC payload notify MST branch using
> > DPCD
> > > or @@ -342,7 +341,7 @@ bool
> > dm_helpers_dp_mst_send_payload_allocation(
> > >     struct amdgpu_dm_connector *aconnector;
> > >     struct drm_dp_mst_topology_state *mst_state;
> > >     struct drm_dp_mst_topology_mgr *mst_mgr;
> > > -   struct drm_dp_mst_atomic_payload *payload;
> > > +   struct drm_dp_mst_atomic_payload *new_payload, *old_payload;
> > >     enum mst_progress_status set_flag =
> > MST_ALLOCATE_NEW_PAYLOAD;
> > >     enum mst_progress_status clr_flag =
> > MST_CLEAR_ALLOCATED_PAYLOAD;
> > >     int ret = 0;
> > > @@ -355,15 +354,20 @@ bool
> > dm_helpers_dp_mst_send_payload_allocation(
> > >     mst_mgr = &aconnector->mst_root->mst_mgr;
> > >     mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
> > > 
> > > -   payload = drm_atomic_get_mst_payload_state(mst_state,
> > aconnector->mst_output_port);
> > > +   new_payload = drm_atomic_get_mst_payload_state(mst_state,
> > > +aconnector->mst_output_port);
> > > 
> > >     if (!enable) {
> > >             set_flag = MST_CLEAR_ALLOCATED_PAYLOAD;
> > >             clr_flag = MST_ALLOCATE_NEW_PAYLOAD;
> > >     }
> > > 
> > > -   if (enable)
> > > -           ret = drm_dp_add_payload_part2(mst_mgr, mst_state-
> > > base.state, payload);
> > > +   if (enable) {
> > > +           ret = drm_dp_add_payload_part2(mst_mgr, mst_state-
> > > base.state, new_payload);
> > > +   } else {
> > > +           dm_helpers_construct_old_payload(stream->link, mst_state-
> > > pbn_div,
> > > +                                            new_payload, old_payload);
> > > +           drm_dp_remove_payload_part2(mst_mgr, mst_state,
> > old_payload, new_payload);
> > > +   }
> > > 
> > >     if (ret) {
> > >             amdgpu_dm_set_mst_status(&aconnector->mst_status,
> > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > index 4d80426757ab..e04f87ff755a 100644
> > > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > @@ -3255,15 +3255,15 @@ int
> > drm_dp_send_query_stream_enc_status(struct
> > > drm_dp_mst_topology_mgr *mgr,  }
> > > EXPORT_SYMBOL(drm_dp_send_query_stream_enc_status);
> > > 
> > > -static int drm_dp_create_payload_step1(struct drm_dp_mst_topology_mgr
> > *mgr,
> > > -                                  struct drm_dp_mst_atomic_payload
> > *payload)
> > > +static int drm_dp_create_payload_at_dfp(struct
> > drm_dp_mst_topology_mgr *mgr,
> > > +                                   struct drm_dp_mst_atomic_payload
> > *payload)
> > >  {
> > >     return drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload-
> > > vc_start_slot,
> > >                                      payload->time_slots);
> > >  }
> > > 
> > > -static int drm_dp_create_payload_step2(struct drm_dp_mst_topology_mgr
> > *mgr,
> > > -                                  struct drm_dp_mst_atomic_payload
> > *payload)
> > > +static int drm_dp_create_payload_to_remote(struct
> > drm_dp_mst_topology_mgr *mgr,
> > > +                                      struct drm_dp_mst_atomic_payload
> > *payload)
> > >  {
> > >     int ret;
> > >     struct drm_dp_mst_port *port =
> > > drm_dp_mst_topology_get_port_validated(mgr, payload->port); @@ -
> > 3276,17 +3276,20 @@ static int drm_dp_create_payload_step2(struct
> > drm_dp_mst_topology_mgr *mgr,
> > >     return ret;
> > >  }
> > > 
> > > -static int drm_dp_destroy_payload_step1(struct
> > drm_dp_mst_topology_mgr *mgr,
> > > -                                   struct drm_dp_mst_topology_state
> > *mst_state,
> > > -                                   struct drm_dp_mst_atomic_payload
> > *payload)
> > > +static void drm_dp_destroy_payload_at_remote_and_dfp(struct
> > drm_dp_mst_topology_mgr *mgr,
> > > +                                                struct
> > drm_dp_mst_topology_state *mst_state,
> > > +                                                struct
> > drm_dp_mst_atomic_payload *payload)
> > >  {
> > >     drm_dbg_kms(mgr->dev, "\n");
> > > 
> > >     /* it's okay for these to fail */
> > > -   drm_dp_payload_send_msg(mgr, payload->port, payload->vcpi, 0);
> > > -   drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload-
> > > vc_start_slot, 0);
> > > +   if (payload->payload_allocation_status ==
> > DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE) {
> > > +           drm_dp_payload_send_msg(mgr, payload->port, payload-
> > > vcpi, 0);
> > > +           payload->payload_allocation_status =
> > DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
> > > +   }
> > > 
> > > -   return 0;
> > > +   if (payload->payload_allocation_status ==
> > DRM_DP_MST_PAYLOAD_ALLOCATION_DFP)
> > > +           drm_dp_dpcd_write_payload(mgr, payload->vcpi,
> > > +payload->vc_start_slot, 0);
> > >  }
> > > 
> > >  /**
> > > @@ -3296,81 +3299,105 @@ static int
> > drm_dp_destroy_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
> > >   * @payload: The payload to write
> > >   *
> > >   * Determines the starting time slot for the given payload, and
> > > programs the VCPI for this payload
> > > - * into hardware. After calling this, the driver should generate ACT and
> > payload packets.
> > > + * into the DPCD of DPRX. After calling this, the driver should generate ACT
> > and payload packets.
> > >   *
> > > - * Returns: 0 on success, error code on failure. In the event that
> > > this fails,
> > > - * @payload.vc_start_slot will also be set to -1.
> > > + * Returns: 0 on success, error code on failure.
> > >   */
> > >  int drm_dp_add_payload_part1(struct drm_dp_mst_topology_mgr *mgr,
> > >                          struct drm_dp_mst_topology_state *mst_state,
> > >                          struct drm_dp_mst_atomic_payload *payload)  {
> > >     struct drm_dp_mst_port *port;
> > > -   int ret;
> > > +   int ret = 0;
> > > +   bool allocate = true;
> > > +
> > > +   /* Update mst mgr info */
> > > +   if (mgr->payload_count == 0)
> > > +           mgr->next_start_slot = mst_state->start_slot;
> > > +
> > > +   payload->vc_start_slot = mgr->next_start_slot;
> > > +
> > > +   mgr->payload_count++;
> > > +   mgr->next_start_slot += payload->time_slots;
> > > 
> > > +   /* Allocate payload to immediate downstream facing port */
> > >     port = drm_dp_mst_topology_get_port_validated(mgr, payload-
> > > port);
> > >     if (!port) {
> > >             drm_dbg_kms(mgr->dev,
> > > -                       "VCPI %d for port %p not in topology, not creating a
> > payload\n",
> > > +                       "VCPI %d for port %p not in topology, not creating a
> > payload
> > > +to remote\n",
> > >                         payload->vcpi, payload->port);
> > > -           payload->vc_start_slot = -1;
> > > -           return 0;
> > > +           allocate = false;
> > >     }
> > > 
> > > -   if (mgr->payload_count == 0)
> > > -           mgr->next_start_slot = mst_state->start_slot;
> > > -
> > > -   payload->vc_start_slot = mgr->next_start_slot;
> > > +   if (allocate) {
> > > +           ret = drm_dp_create_payload_at_dfp(mgr, payload);
> > > +           if (ret < 0)
> > > +                   drm_warn(mgr->dev, "Failed to create MST payload
> > for port %p: %d\n",
> > > +                            payload->port, ret);
> > > 
> > > -   ret = drm_dp_create_payload_step1(mgr, payload);
> > > -   drm_dp_mst_topology_put_port(port);
> > > -   if (ret < 0) {
> > > -           drm_warn(mgr->dev, "Failed to create MST payload for port
> > %p: %d\n",
> > > -                    payload->port, ret);
> > > -           payload->vc_start_slot = -1;
> > > -           return ret;
> > >     }
> > > 
> > > -   mgr->payload_count++;
> > > -   mgr->next_start_slot += payload->time_slots;
> > > +   payload->payload_allocation_status =
> > > +           (!allocate || ret < 0) ?
> > DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL :
> > > +
> >       DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
> > 
> > Just need to fix indenting here
> > 
> > > 
> > > -   return 0;
> > > +   drm_dp_mst_topology_put_port(port);
> > > +
> > > +   return ret;
> > >  }
> > >  EXPORT_SYMBOL(drm_dp_add_payload_part1);
> > > 
> > >  /**
> > > - * drm_dp_remove_payload() - Remove an MST payload
> > > + * drm_dp_remove_payload_part1() - Remove an MST payload along the
> > > + virtual channel
> > >   * @mgr: Manager to use.
> > >   * @mst_state: The MST atomic state
> > > - * @old_payload: The payload with its old state
> > > - * @new_payload: The payload to write
> > > + * @payload: The payload to remove
> > >   *
> > > - * Removes a payload from an MST topology if it was successfully
> > > assigned a start slot. Also updates
> > > - * the starting time slots of all other payloads which would have
> > > been shifted towards the start of
> > > - * the VC table as a result. After calling this, the driver should generate ACT
> > and payload packets.
> > > + * Removes a payload along the virtual channel if it was successfully
> > allocated.
> > > + * After calling this, the driver should set HW to generate ACT and
> > > + then switch to new
> > > + * payload allocation state.
> > >   */
> > > -void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
> > > -                      struct drm_dp_mst_topology_state *mst_state,
> > > -                      const struct drm_dp_mst_atomic_payload
> > *old_payload,
> > > -                      struct drm_dp_mst_atomic_payload *new_payload)
> > > +void drm_dp_remove_payload_part1(struct drm_dp_mst_topology_mgr
> > *mgr,
> > > +                            struct drm_dp_mst_topology_state
> > *mst_state,
> > > +                            struct drm_dp_mst_atomic_payload
> > *payload)
> > >  {
> > > -   struct drm_dp_mst_atomic_payload *pos;
> > > +   /* Remove remote payload allocation */
> > >     bool send_remove = false;
> > > 
> > > -   /* We failed to make the payload, so nothing to do */
> > > -   if (new_payload->vc_start_slot == -1)
> > > -           return;
> > > -
> > >     mutex_lock(&mgr->lock);
> > > -   send_remove =
> > drm_dp_mst_port_downstream_of_branch(new_payload->port, mgr-
> > > mst_primary);
> > > +   send_remove = drm_dp_mst_port_downstream_of_branch(payload-
> > > port,
> > > +mgr->mst_primary);
> > >     mutex_unlock(&mgr->lock);
> > > 
> > >     if (send_remove)
> > > -           drm_dp_destroy_payload_step1(mgr, mst_state,
> > new_payload);
> > > +           drm_dp_destroy_payload_at_remote_and_dfp(mgr,
> > mst_state, payload);
> > >     else
> > >             drm_dbg_kms(mgr->dev, "Payload for VCPI %d not in
> > topology, not sending remove\n",
> > > -                       new_payload->vcpi);
> > > +                       payload->vcpi);
> > > +
> > > +   payload->payload_allocation_status =
> > > +DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL;
> > > +}
> > > +EXPORT_SYMBOL(drm_dp_remove_payload_part1);
> > > 
> > > +/**
> > > + * drm_dp_remove_payload_part2() - Remove an MST payload locally
> > > + * @mgr: Manager to use.
> > > + * @mst_state: The MST atomic state
> > > + * @old_payload: The payload with its old state
> > > + * @new_payload: The payload with its latest state
> > > + *
> > > + * Updates the starting time slots of all other payloads which would
> > > +have been shifted towards
> > > + * the start of the payload ID table as a result of removing a
> > > +payload. Driver should call this
> > > + * function whenever it removes a payload in its HW. It's independent
> > > +to the result of payload
> > > + * allocation/deallocation at branch devices along the virtual channel.
> > > + */
> > > +void drm_dp_remove_payload_part2(struct drm_dp_mst_topology_mgr
> > *mgr,
> > > +                            struct drm_dp_mst_topology_state
> > *mst_state,
> > > +                            const struct drm_dp_mst_atomic_payload
> > *old_payload,
> > > +                            struct drm_dp_mst_atomic_payload
> > *new_payload) {
> > > +   struct drm_dp_mst_atomic_payload *pos;
> > > +
> > > +   /* Remove local payload allocation */
> > >     list_for_each_entry(pos, &mst_state->payloads, next) {
> > >             if (pos != new_payload && pos->vc_start_slot > new_payload-
> > > vc_start_slot)
> > >                     pos->vc_start_slot -= old_payload->time_slots; @@ -
> > 3382,9 +3409,10
> > > @@ void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr
> > *mgr,
> > > 
> > >     if (new_payload->delete)
> > >             drm_dp_mst_put_port_malloc(new_payload->port);
> > > -}
> > > -EXPORT_SYMBOL(drm_dp_remove_payload);
> > > 
> > > +   new_payload->payload_allocation_status =
> > > +DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
> > > +}
> > > +EXPORT_SYMBOL(drm_dp_remove_payload_part2);
> > >  /**
> > >   * drm_dp_add_payload_part2() - Execute payload update part 2
> > >   * @mgr: Manager to use.
> > > @@ -3403,17 +3431,19 @@ int drm_dp_add_payload_part2(struct
> > drm_dp_mst_topology_mgr *mgr,
> > >     int ret = 0;
> > > 
> > >     /* Skip failed payloads */
> > > -   if (payload->vc_start_slot == -1) {
> > > -           drm_dbg_kms(mgr->dev, "Part 1 of payload creation for %s
> > failed, skipping part 2\n",
> > > +   if (payload->payload_allocation_status !=
> > DRM_DP_MST_PAYLOAD_ALLOCATION_DFP) {
> > > +           drm_dbg_kms(state->dev, "Part 1 of payload creation for %s
> > failed,
> > > +skipping part 2\n",
> > >                         payload->port->connector->name);
> > >             return -EIO;
> > >     }
> > > 
> > > -   ret = drm_dp_create_payload_step2(mgr, payload);
> > > -   if (ret < 0) {
> > > +   /* Allocate payload to remote end */
> > > +   ret = drm_dp_create_payload_to_remote(mgr, payload);
> > > +   if (ret < 0)
> > >             drm_err(mgr->dev, "Step 2 of creating MST payload for %p
> > failed: %d\n",
> > >                     payload->port, ret);
> > > -   }
> > > +   else
> > > +           payload->payload_allocation_status =
> > > +DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE;
> > > 
> > >     return ret;
> > >  }
> > > @@ -4324,6 +4354,7 @@ int drm_dp_atomic_find_time_slots(struct
> > drm_atomic_state *state,
> > >             drm_dp_mst_get_port_malloc(port);
> > >             payload->port = port;
> > >             payload->vc_start_slot = -1;
> > > +           payload->payload_allocation_status =
> > > +DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
> > >             list_add(&payload->next, &topology_state->payloads);
> > >     }
> > >     payload->time_slots = req_slots;
> > > @@ -4493,7 +4524,7 @@ void
> > drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state
> > *state)
> > >             }
> > > 
> > >             /* Now that previous state is committed, it's safe to copy over
> > the start slot
> > > -            * assignments
> > > +            * and allocation status assignments
> > >              */
> > >             list_for_each_entry(old_payload, &old_mst_state->payloads,
> > next) {
> > >                     if (old_payload->delete)
> > > @@ -4502,6 +4533,8 @@ void
> > drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state
> > *state)
> > >                     new_payload =
> > drm_atomic_get_mst_payload_state(new_mst_state,
> > > 
> > old_payload->port);
> > >                     new_payload->vc_start_slot = old_payload-
> > > vc_start_slot;
> > > +                   new_payload->payload_allocation_status =
> > > +                                                   old_payload-
> > > payload_allocation_status;
> > 
> > And here. Besides that, I think patches 1/3 and 2/3 look great! Just finished
> > testing them on nouveau:
> > 
> > Reviewed-by: Lyude Paul <lyude@redhat.com>
> > 
> > Patch 3/3 I gotta think about a bit more (and am curious about Imre's current
> > take on it) I think
> > 
> > >             }
> > >     }
> > >  }
> > > @@ -4818,6 +4851,13 @@ void drm_dp_mst_dump_topology(struct
> > seq_file *m,
> > >     struct drm_dp_mst_atomic_payload *payload;
> > >     int i, ret;
> > > 
> > > +   static const char *const status[] = {
> > > +           "None",
> > > +           "Local",
> > > +           "DFP",
> > > +           "Remote",
> > > +   };
> > > +
> > >     mutex_lock(&mgr->lock);
> > >     if (mgr->mst_primary)
> > >             drm_dp_mst_dump_mstb(m, mgr->mst_primary); @@ -
> > 4834,7 +4874,7 @@
> > > void drm_dp_mst_dump_topology(struct seq_file *m,
> > >     seq_printf(m, "payload_mask: %x, max_payloads: %d, start_slot: %u,
> > pbn_div: %d\n",
> > >                state->payload_mask, mgr->max_payloads, state-
> > > start_slot,
> > > state->pbn_div);
> > > 
> > > -   seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc |     sink name
> > > \n");
> > > +   seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc | status |     sink
> > name     |\n");
> > >     for (i = 0; i < mgr->max_payloads; i++) {
> > >             list_for_each_entry(payload, &state->payloads, next) {
> > >                     char name[14];
> > > @@ -4843,7 +4883,7 @@ void drm_dp_mst_dump_topology(struct
> > seq_file *m,
> > >                             continue;
> > > 
> > >                     fetch_monitor_name(mgr, payload->port, name,
> > sizeof(name));
> > > -                   seq_printf(m, " %5d %6d %6d %02d - %02d %5d %5s
> > %19s\n",
> > > +                   seq_printf(m, " %5d %6d %6d %02d - %02d %5d %5s
> > %8s %19s\n",
> > >                                i,
> > >                                payload->port->port_num,
> > >                                payload->vcpi,
> > > @@ -4851,6 +4891,7 @@ void drm_dp_mst_dump_topology(struct
> > seq_file *m,
> > >                                payload->vc_start_slot + payload-
> > > time_slots - 1,
> > >                                payload->pbn,
> > >                                payload->dsc_enabled ? "Y" : "N",
> > > +                              status[payload->payload_allocation_status],
> > >                                (*name != 0) ? name : "Unknown");
> > >             }
> > >     }
> > > diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > index e3f176a093d2..5f73cdabe7a1 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > @@ -557,12 +557,8 @@ static void intel_mst_disable_dp(struct
> > intel_atomic_state *state,
> > >     struct intel_dp *intel_dp = &dig_port->dp;
> > >     struct intel_connector *connector =
> > >             to_intel_connector(old_conn_state->connector);
> > > -   struct drm_dp_mst_topology_state *old_mst_state =
> > > -           drm_atomic_get_old_mst_topology_state(&state->base,
> > &intel_dp->mst_mgr);
> > >     struct drm_dp_mst_topology_state *new_mst_state =
> > >             drm_atomic_get_new_mst_topology_state(&state->base,
> > &intel_dp->mst_mgr);
> > > -   const struct drm_dp_mst_atomic_payload *old_payload =
> > > -           drm_atomic_get_mst_payload_state(old_mst_state,
> > connector->port);
> > >     struct drm_dp_mst_atomic_payload *new_payload =
> > >             drm_atomic_get_mst_payload_state(new_mst_state,
> > connector->port);
> > >     struct drm_i915_private *i915 = to_i915(connector->base.dev); @@
> > > -572,8 +568,7 @@ static void intel_mst_disable_dp(struct
> > > intel_atomic_state *state,
> > > 
> > >     intel_hdcp_disable(intel_mst->connector);
> > > 
> > > -   drm_dp_remove_payload(&intel_dp->mst_mgr, new_mst_state,
> > > -                         old_payload, new_payload);
> > > +   drm_dp_remove_payload_part1(&intel_dp->mst_mgr,
> > new_mst_state,
> > > +new_payload);
> > > 
> > >     intel_audio_codec_disable(encoder, old_crtc_state, old_conn_state);
> > > } @@ -588,6 +583,14 @@ static void intel_mst_post_disable_dp(struct
> > > intel_atomic_state *state,
> > >     struct intel_dp *intel_dp = &dig_port->dp;
> > >     struct intel_connector *connector =
> > >             to_intel_connector(old_conn_state->connector);
> > > +   struct drm_dp_mst_topology_state *old_mst_state =
> > > +           drm_atomic_get_old_mst_topology_state(&state->base,
> > &intel_dp->mst_mgr);
> > > +   struct drm_dp_mst_topology_state *new_mst_state =
> > > +           drm_atomic_get_new_mst_topology_state(&state->base,
> > &intel_dp->mst_mgr);
> > > +   const struct drm_dp_mst_atomic_payload *old_payload =
> > > +           drm_atomic_get_mst_payload_state(old_mst_state,
> > connector->port);
> > > +   struct drm_dp_mst_atomic_payload *new_payload =
> > > +           drm_atomic_get_mst_payload_state(new_mst_state,
> > connector->port);
> > >     struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
> > >     bool last_mst_stream;
> > > 
> > > @@ -608,6 +611,9 @@ static void intel_mst_post_disable_dp(struct
> > > intel_atomic_state *state,
> > > 
> > >     wait_for_act_sent(encoder, old_crtc_state);
> > > 
> > > +   drm_dp_remove_payload_part2(&intel_dp->mst_mgr,
> > new_mst_state,
> > > +                               old_payload, new_payload);
> > > +
> > >     intel_ddi_disable_transcoder_func(old_crtc_state);
> > > 
> > >     if (DISPLAY_VER(dev_priv) >= 9)
> > > diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > index 4e7c9c353c51..bba01fa0780c 100644
> > > --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > @@ -882,21 +882,26 @@ struct nouveau_encoder *nv50_real_outp(struct
> > > drm_encoder *encoder)
> > > 
> > >  static void
> > >  nv50_msto_cleanup(struct drm_atomic_state *state,
> > > -             struct drm_dp_mst_topology_state *mst_state,
> > > +             struct drm_dp_mst_topology_state *new_mst_state,
> > >               struct drm_dp_mst_topology_mgr *mgr,
> > >               struct nv50_msto *msto)
> > >  {
> > >     struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
> > > -   struct drm_dp_mst_atomic_payload *payload =
> > > -           drm_atomic_get_mst_payload_state(mst_state, msto->mstc-
> > > port);
> > > +   struct drm_dp_mst_atomic_payload *new_payload =
> > > +           drm_atomic_get_mst_payload_state(new_mst_state, msto-
> > > mstc->port);
> > > +   struct drm_dp_mst_topology_state *old_mst_state =
> > > +           drm_atomic_get_old_mst_topology_state(state, mgr);
> > > +   const struct drm_dp_mst_atomic_payload *old_payload =
> > > +           drm_atomic_get_mst_payload_state(old_mst_state, msto-
> > > mstc->port);
> > > 
> > >     NV_ATOMIC(drm, "%s: msto cleanup\n", msto->encoder.name);
> > > 
> > >     if (msto->disabled) {
> > >             msto->mstc = NULL;
> > >             msto->disabled = false;
> > > +           drm_dp_remove_payload_part2(mgr, new_mst_state,
> > old_payload,
> > > +new_payload);
> > >     } else if (msto->enabled) {
> > > -           drm_dp_add_payload_part2(mgr, state, payload);
> > > +           drm_dp_add_payload_part2(mgr, state, new_payload);
> > >             msto->enabled = false;
> > >     }
> > >  }
> > > @@ -910,19 +915,15 @@ nv50_msto_prepare(struct drm_atomic_state
> > *state,
> > >     struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
> > >     struct nv50_mstc *mstc = msto->mstc;
> > >     struct nv50_mstm *mstm = mstc->mstm;
> > > -   struct drm_dp_mst_topology_state *old_mst_state;
> > > -   struct drm_dp_mst_atomic_payload *payload, *old_payload;
> > > +   struct drm_dp_mst_atomic_payload *payload;
> > > 
> > >     NV_ATOMIC(drm, "%s: msto prepare\n", msto->encoder.name);
> > > 
> > > -   old_mst_state = drm_atomic_get_old_mst_topology_state(state,
> > mgr);
> > > -
> > >     payload = drm_atomic_get_mst_payload_state(mst_state, mstc-
> > > port);
> > > -   old_payload = drm_atomic_get_mst_payload_state(old_mst_state,
> > mstc->port);
> > > 
> > >     // TODO: Figure out if we want to do a better job of handling VCPI
> > allocation failures here?
> > >     if (msto->disabled) {
> > > -           drm_dp_remove_payload(mgr, mst_state, old_payload,
> > payload);
> > > +           drm_dp_remove_payload_part1(mgr, mst_state, payload);
> > > 
> > >             nvif_outp_dp_mst_vcpi(&mstm->outp->outp, msto->head-
> > > base.index, 0, 0, 0, 0);
> > >     } else {
> > > diff --git a/include/drm/display/drm_dp_mst_helper.h
> > > b/include/drm/display/drm_dp_mst_helper.h
> > > index ed5c9660563c..4429d3b1745b 100644
> > > --- a/include/drm/display/drm_dp_mst_helper.h
> > > +++ b/include/drm/display/drm_dp_mst_helper.h
> > > @@ -46,6 +46,13 @@ struct drm_dp_mst_topology_ref_history {  };
> > > #endif /* IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) */
> > > 
> > > +enum drm_dp_mst_payload_allocation {
> > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_NONE,
> > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL,
> > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_DFP,
> > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE,
> > > +};
> > > +
> > >  struct drm_dp_mst_branch;
> > > 
> > >  /**
> > > @@ -537,7 +544,7 @@ struct drm_dp_mst_atomic_payload {
> > >      *   drm_dp_mst_atomic_wait_for_dependencies() has been called,
> > which will ensure the
> > >      *   previous MST states payload start slots have been copied over to
> > the new state. Note
> > >      *   that a new start slot won't be assigned/removed from this payload
> > until
> > > -    *   drm_dp_add_payload_part1()/drm_dp_remove_payload() have
> > been called.
> > > +    *   drm_dp_add_payload_part1()/drm_dp_remove_payload_part2()
> > have been called.
> > >      * * Acquire the MST modesetting lock, and then wait for any pending
> > MST-related commits to
> > >      *   get committed to hardware by calling drm_crtc_commit_wait() on
> > each of the
> > >      *   &drm_crtc_commit structs in
> > &drm_dp_mst_topology_state.commit_deps.
> > > @@ -564,6 +571,9 @@ struct drm_dp_mst_atomic_payload {
> > >     /** @dsc_enabled: Whether or not this payload has DSC enabled */
> > >     bool dsc_enabled : 1;
> > > 
> > > +   /** @payload_allocation_status: The allocation status of this payload
> > */
> > > +   enum drm_dp_mst_payload_allocation payload_allocation_status;
> > > +
> > >     /** @next: The list node for this payload */
> > >     struct list_head next;
> > >  };
> > > @@ -842,10 +852,13 @@ int drm_dp_add_payload_part1(struct
> > > drm_dp_mst_topology_mgr *mgr,  int drm_dp_add_payload_part2(struct
> > drm_dp_mst_topology_mgr *mgr,
> > >                          struct drm_atomic_state *state,
> > >                          struct drm_dp_mst_atomic_payload *payload); -
> > void
> > > drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
> > > -                      struct drm_dp_mst_topology_state *mst_state,
> > > -                      const struct drm_dp_mst_atomic_payload
> > *old_payload,
> > > -                      struct drm_dp_mst_atomic_payload
> > *new_payload);
> > > +void drm_dp_remove_payload_part1(struct drm_dp_mst_topology_mgr
> > *mgr,
> > > +                            struct drm_dp_mst_topology_state
> > *mst_state,
> > > +                            struct drm_dp_mst_atomic_payload
> > *payload); void
> > > +drm_dp_remove_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
> > > +                            struct drm_dp_mst_topology_state
> > *mst_state,
> > > +                            const struct drm_dp_mst_atomic_payload
> > *old_payload,
> > > +                            struct drm_dp_mst_atomic_payload
> > *new_payload);
> > > 
> > >  int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr);
> > > 
> > 
> > --
> > Cheers,
> >  Lyude Paul (she/her)
> >  Software Engineer at Red Hat
> --
> Regards,
> Wayne

-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat

RE: [Patch v2 2/3] drm/mst: Refactor the flow for payload allocation/removement

[Lin, Wayne]

[Public]

Hi Lyude,

I'm afraid that I don't have the permissions to push and would like to have
your help. Thanks!

> -----Original Message-----
> From: Lyude Paul <lyude@redhat.com>
> Sent: Thursday, August 24, 2023 5:00 AM
> To: Lin, Wayne <Wayne.Lin@amd.com>; dri-devel@lists.freedesktop.org;
> amd-gfx@lists.freedesktop.org
> Cc: jani.nikula@intel.com; ville.syrjala@linux.intel.com; imre.deak@intel.com;
> Wentland, Harry <Harry.Wentland@amd.com>; Zuo, Jerry
> <Jerry.Zuo@amd.com>
> Subject: Re: [Patch v2 2/3] drm/mst: Refactor the flow for payload
> allocation/removement
>
> Sure - you're also welcome to push the first two patches after fixing the
> indentation if you'd like
>
> On Wed, 2023-08-23 at 03:19 +0000, Lin, Wayne wrote:
> > [Public]
> >
> > Thanks, Lyude!
> > Should I push another version to fix the indention?
> >
> > > -----Original Message-----
> > > From: Lyude Paul <lyude@redhat.com>
> > > Sent: Friday, August 18, 2023 6:17 AM
> > > To: Lin, Wayne <Wayne.Lin@amd.com>; dri-devel@lists.freedesktop.org;
> > > amd-gfx@lists.freedesktop.org
> > > Cc: jani.nikula@intel.com; ville.syrjala@linux.intel.com;
> > > imre.deak@intel.com; Wentland, Harry <Harry.Wentland@amd.com>; Zuo,
> > > Jerry <Jerry.Zuo@amd.com>
> > > Subject: Re: [Patch v2 2/3] drm/mst: Refactor the flow for payload
> > > allocation/removement
> > >
> > > Two small comments:
> > >
> > > On Mon, 2023-08-07 at 10:56 +0800, Wayne Lin wrote:
> > > > [Why]
> > > > Today, the allocation/deallocation steps and status is a bit unclear.
> > > >
> > > > For instance, payload->vc_start_slot = -1 stands for "the failure
> > > > of updating DPCD payload ID table" and can also represent as
> > > > "payload is not allocated yet". These two cases should be handled
> > > > differently and hence better to distinguish them for better understanding.
> > > >
> > > > [How]
> > > > Define enumeration - ALLOCATION_LOCAL, ALLOCATION_DFP and
> > > > ALLOCATION_REMOTE to distinguish different allocation status.
> > > > Adjust the code to handle different status accordingly for better
> > > > understanding the sequence of payload allocation and payload
> > > removement.
> > > >
> > > > For payload creation, the procedure should look like this:
> > > > DRM part 1:
> > > > * step 1 - update sw mst mgr variables to add a new payload
> > > > * step 2 - add payload at immediate DFP DPCD payload table
> > > >
> > > > Driver:
> > > > * Add new payload in HW and sync up with DFP by sending ACT
> > > >
> > > > DRM Part 2:
> > > > * Send ALLOCATE_PAYLOAD sideband message to allocate bandwidth
> > > > along
> > > the
> > > >   virtual channel.
> > > >
> > > > And as for payload removement, the procedure should look like this:
> > > > DRM part 1:
> > > > * step 1 - Send ALLOCATE_PAYLOAD sideband message to release
> bandwidth
> > > >            along the virtual channel
> > > > * step 2 - Clear payload allocation at immediate DFP DPCD payload
> > > > table
> > > >
> > > > Driver:
> > > > * Remove the payload in HW and sync up with DFP by sending ACT
> > > >
> > > > DRM part 2:
> > > > * update sw mst mgr variables to remove the payload
> > > >
> > > > Note that it's fine to fail when communicate with the branch
> > > > device connected at immediate downstrean-facing port, but updating
> > > > variables of SW mst mgr and HW configuration should be conducted
> > > > anyway. That's because it's under commit_tail and we need to
> > > > complete the HW
> > > programming.
> > > >
> > > > Changes since v1:
> > > > * Remove the set but not use variable 'old_payload' in function
> > > >   'nv50_msto_prepare'. Catched by kernel test robot
> > > > <lkp@intel.com>
> > > >
> > > > Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
> > > > ---
> > > >  .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  20 ++-
> > > > drivers/gpu/drm/display/drm_dp_mst_topology.c | 159
> > > > +++++++++++------
> > > -
> > > >  drivers/gpu/drm/i915/display/intel_dp_mst.c   |  18 +-
> > > >  drivers/gpu/drm/nouveau/dispnv50/disp.c       |  21 +--
> > > >  include/drm/display/drm_dp_mst_helper.h       |  23 ++-
> > > >  5 files changed, 153 insertions(+), 88 deletions(-)
> > > >
> > > > diff --git
> > > a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > > index d9a482908380..9ad509279b0a 100644
> > > > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > > +++
> b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > > @@ -219,7 +219,7 @@ static void dm_helpers_construct_old_payload(
> > > >     /* Set correct time_slots/PBN of old payload.
> > > >      * other fields (delete & dsc_enabled) in
> > > >      * struct drm_dp_mst_atomic_payload are don't care fields
> > > > -    * while calling drm_dp_remove_payload()
> > > > +    * while calling drm_dp_remove_payload_part2()
> > > >      */
> > > >     for (i = 0; i < current_link_table.stream_count; i++) {
> > > >             dc_alloc =
> > > > @@ -262,13 +262,12 @@ bool
> > > > dm_helpers_dp_mst_write_payload_allocation_table(
> > > >
> > > >     mst_mgr = &aconnector->mst_root->mst_mgr;
> > > >     mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
> > > > -
> > > > -   /* It's OK for this to fail */
> > > >     new_payload = drm_atomic_get_mst_payload_state(mst_state,
> > > > aconnector->mst_output_port);
> > > >
> > > >     if (enable) {
> > > >             target_payload = new_payload;
> > > >
> > > > +           /* It's OK for this to fail */
> > > >             drm_dp_add_payload_part1(mst_mgr, mst_state,
> > > new_payload);
> > > >     } else {
> > > >             /* construct old payload by VCPI*/ @@ -276,7 +275,7 @@
> > > > bool
> > > dm_helpers_dp_mst_write_payload_allocation_table(
> > > >                                             new_payload, &old_payload);
> > > >             target_payload = &old_payload;
> > > >
> > > > -           drm_dp_remove_payload(mst_mgr, mst_state,
> > > &old_payload, new_payload);
> > > > +           drm_dp_remove_payload_part1(mst_mgr, mst_state,
> > > new_payload);
> > > >     }
> > > >
> > > >     /* mst_mgr->->payloads are VC payload notify MST branch using
> > > DPCD
> > > > or @@ -342,7 +341,7 @@ bool
> > > dm_helpers_dp_mst_send_payload_allocation(
> > > >     struct amdgpu_dm_connector *aconnector;
> > > >     struct drm_dp_mst_topology_state *mst_state;
> > > >     struct drm_dp_mst_topology_mgr *mst_mgr;
> > > > -   struct drm_dp_mst_atomic_payload *payload;
> > > > +   struct drm_dp_mst_atomic_payload *new_payload, *old_payload;
> > > >     enum mst_progress_status set_flag =
> > > MST_ALLOCATE_NEW_PAYLOAD;
> > > >     enum mst_progress_status clr_flag =
> > > MST_CLEAR_ALLOCATED_PAYLOAD;
> > > >     int ret = 0;
> > > > @@ -355,15 +354,20 @@ bool
> > > dm_helpers_dp_mst_send_payload_allocation(
> > > >     mst_mgr = &aconnector->mst_root->mst_mgr;
> > > >     mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
> > > >
> > > > -   payload = drm_atomic_get_mst_payload_state(mst_state,
> > > aconnector->mst_output_port);
> > > > +   new_payload = drm_atomic_get_mst_payload_state(mst_state,
> > > > +aconnector->mst_output_port);
> > > >
> > > >     if (!enable) {
> > > >             set_flag = MST_CLEAR_ALLOCATED_PAYLOAD;
> > > >             clr_flag = MST_ALLOCATE_NEW_PAYLOAD;
> > > >     }
> > > >
> > > > -   if (enable)
> > > > -           ret = drm_dp_add_payload_part2(mst_mgr, mst_state-
> > > > base.state, payload);
> > > > +   if (enable) {
> > > > +           ret = drm_dp_add_payload_part2(mst_mgr, mst_state-
> > > > base.state, new_payload);
> > > > +   } else {
> > > > +           dm_helpers_construct_old_payload(stream->link,
> > > > + mst_state-
> > > > pbn_div,
> > > > +                                            new_payload, old_payload);
> > > > +           drm_dp_remove_payload_part2(mst_mgr, mst_state,
> > > old_payload, new_payload);
> > > > +   }
> > > >
> > > >     if (ret) {
> > > >             amdgpu_dm_set_mst_status(&aconnector->mst_status,
> > > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > > b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > > index 4d80426757ab..e04f87ff755a 100644
> > > > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > > @@ -3255,15 +3255,15 @@ int
> > > drm_dp_send_query_stream_enc_status(struct
> > > > drm_dp_mst_topology_mgr *mgr,  }
> > > > EXPORT_SYMBOL(drm_dp_send_query_stream_enc_status);
> > > >
> > > > -static int drm_dp_create_payload_step1(struct
> > > > drm_dp_mst_topology_mgr
> > > *mgr,
> > > > -                                  struct drm_dp_mst_atomic_payload
> > > *payload)
> > > > +static int drm_dp_create_payload_at_dfp(struct
> > > drm_dp_mst_topology_mgr *mgr,
> > > > +                                   struct
> > > > + drm_dp_mst_atomic_payload
> > > *payload)
> > > >  {
> > > >     return drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload-
> > > > vc_start_slot,
> > > >                                      payload->time_slots);  }
> > > >
> > > > -static int drm_dp_create_payload_step2(struct
> > > > drm_dp_mst_topology_mgr
> > > *mgr,
> > > > -                                  struct drm_dp_mst_atomic_payload
> > > *payload)
> > > > +static int drm_dp_create_payload_to_remote(struct
> > > drm_dp_mst_topology_mgr *mgr,
> > > > +                                      struct
> > > > + drm_dp_mst_atomic_payload
> > > *payload)
> > > >  {
> > > >     int ret;
> > > >     struct drm_dp_mst_port *port =
> > > > drm_dp_mst_topology_get_port_validated(mgr, payload->port); @@ -
> > > 3276,17 +3276,20 @@ static int drm_dp_create_payload_step2(struct
> > > drm_dp_mst_topology_mgr *mgr,
> > > >     return ret;
> > > >  }
> > > >
> > > > -static int drm_dp_destroy_payload_step1(struct
> > > drm_dp_mst_topology_mgr *mgr,
> > > > -                                   struct drm_dp_mst_topology_state
> > > *mst_state,
> > > > -                                   struct drm_dp_mst_atomic_payload
> > > *payload)
> > > > +static void drm_dp_destroy_payload_at_remote_and_dfp(struct
> > > drm_dp_mst_topology_mgr *mgr,
> > > > +                                                struct
> > > drm_dp_mst_topology_state *mst_state,
> > > > +                                                struct
> > > drm_dp_mst_atomic_payload *payload)
> > > >  {
> > > >     drm_dbg_kms(mgr->dev, "\n");
> > > >
> > > >     /* it's okay for these to fail */
> > > > -   drm_dp_payload_send_msg(mgr, payload->port, payload->vcpi, 0);
> > > > -   drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload-
> > > > vc_start_slot, 0);
> > > > +   if (payload->payload_allocation_status ==
> > > DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE) {
> > > > +           drm_dp_payload_send_msg(mgr, payload->port, payload-
> > > > vcpi, 0);
> > > > +           payload->payload_allocation_status =
> > > DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
> > > > +   }
> > > >
> > > > -   return 0;
> > > > +   if (payload->payload_allocation_status ==
> > > DRM_DP_MST_PAYLOAD_ALLOCATION_DFP)
> > > > +           drm_dp_dpcd_write_payload(mgr, payload->vcpi,
> > > > +payload->vc_start_slot, 0);
> > > >  }
> > > >
> > > >  /**
> > > > @@ -3296,81 +3299,105 @@ static int
> > > drm_dp_destroy_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
> > > >   * @payload: The payload to write
> > > >   *
> > > >   * Determines the starting time slot for the given payload, and
> > > > programs the VCPI for this payload
> > > > - * into hardware. After calling this, the driver should generate
> > > > ACT and
> > > payload packets.
> > > > + * into the DPCD of DPRX. After calling this, the driver should
> > > > + generate ACT
> > > and payload packets.
> > > >   *
> > > > - * Returns: 0 on success, error code on failure. In the event
> > > > that this fails,
> > > > - * @payload.vc_start_slot will also be set to -1.
> > > > + * Returns: 0 on success, error code on failure.
> > > >   */
> > > >  int drm_dp_add_payload_part1(struct drm_dp_mst_topology_mgr
> *mgr,
> > > >                          struct drm_dp_mst_topology_state *mst_state,
> > > >                          struct drm_dp_mst_atomic_payload *payload)  {
> > > >     struct drm_dp_mst_port *port;
> > > > -   int ret;
> > > > +   int ret = 0;
> > > > +   bool allocate = true;
> > > > +
> > > > +   /* Update mst mgr info */
> > > > +   if (mgr->payload_count == 0)
> > > > +           mgr->next_start_slot = mst_state->start_slot;
> > > > +
> > > > +   payload->vc_start_slot = mgr->next_start_slot;
> > > > +
> > > > +   mgr->payload_count++;
> > > > +   mgr->next_start_slot += payload->time_slots;
> > > >
> > > > +   /* Allocate payload to immediate downstream facing port */
> > > >     port = drm_dp_mst_topology_get_port_validated(mgr, payload-
> > > > port);
> > > >     if (!port) {
> > > >             drm_dbg_kms(mgr->dev,
> > > > -                       "VCPI %d for port %p not in topology, not creating a
> > > payload\n",
> > > > +                       "VCPI %d for port %p not in topology, not
> > > > + creating a
> > > payload
> > > > +to remote\n",
> > > >                         payload->vcpi, payload->port);
> > > > -           payload->vc_start_slot = -1;
> > > > -           return 0;
> > > > +           allocate = false;
> > > >     }
> > > >
> > > > -   if (mgr->payload_count == 0)
> > > > -           mgr->next_start_slot = mst_state->start_slot;
> > > > -
> > > > -   payload->vc_start_slot = mgr->next_start_slot;
> > > > +   if (allocate) {
> > > > +           ret = drm_dp_create_payload_at_dfp(mgr, payload);
> > > > +           if (ret < 0)
> > > > +                   drm_warn(mgr->dev, "Failed to create MST
> > > > + payload
> > > for port %p: %d\n",
> > > > +                            payload->port, ret);
> > > >
> > > > -   ret = drm_dp_create_payload_step1(mgr, payload);
> > > > -   drm_dp_mst_topology_put_port(port);
> > > > -   if (ret < 0) {
> > > > -           drm_warn(mgr->dev, "Failed to create MST payload for port
> > > %p: %d\n",
> > > > -                    payload->port, ret);
> > > > -           payload->vc_start_slot = -1;
> > > > -           return ret;
> > > >     }
> > > >
> > > > -   mgr->payload_count++;
> > > > -   mgr->next_start_slot += payload->time_slots;
> > > > +   payload->payload_allocation_status =
> > > > +           (!allocate || ret < 0) ?
> > > DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL :
> > > > +
> > >       DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
> > >
> > > Just need to fix indenting here
> > >
> > > >
> > > > -   return 0;
> > > > +   drm_dp_mst_topology_put_port(port);
> > > > +
> > > > +   return ret;
> > > >  }
> > > >  EXPORT_SYMBOL(drm_dp_add_payload_part1);
> > > >
> > > >  /**
> > > > - * drm_dp_remove_payload() - Remove an MST payload
> > > > + * drm_dp_remove_payload_part1() - Remove an MST payload along
> > > > + the virtual channel
> > > >   * @mgr: Manager to use.
> > > >   * @mst_state: The MST atomic state
> > > > - * @old_payload: The payload with its old state
> > > > - * @new_payload: The payload to write
> > > > + * @payload: The payload to remove
> > > >   *
> > > > - * Removes a payload from an MST topology if it was successfully
> > > > assigned a start slot. Also updates
> > > > - * the starting time slots of all other payloads which would have
> > > > been shifted towards the start of
> > > > - * the VC table as a result. After calling this, the driver
> > > > should generate ACT
> > > and payload packets.
> > > > + * Removes a payload along the virtual channel if it was
> > > > + successfully
> > > allocated.
> > > > + * After calling this, the driver should set HW to generate ACT
> > > > + and then switch to new
> > > > + * payload allocation state.
> > > >   */
> > > > -void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
> > > > -                      struct drm_dp_mst_topology_state *mst_state,
> > > > -                      const struct drm_dp_mst_atomic_payload
> > > *old_payload,
> > > > -                      struct drm_dp_mst_atomic_payload *new_payload)
> > > > +void drm_dp_remove_payload_part1(struct
> drm_dp_mst_topology_mgr
> > > *mgr,
> > > > +                            struct drm_dp_mst_topology_state
> > > *mst_state,
> > > > +                            struct drm_dp_mst_atomic_payload
> > > *payload)
> > > >  {
> > > > -   struct drm_dp_mst_atomic_payload *pos;
> > > > +   /* Remove remote payload allocation */
> > > >     bool send_remove = false;
> > > >
> > > > -   /* We failed to make the payload, so nothing to do */
> > > > -   if (new_payload->vc_start_slot == -1)
> > > > -           return;
> > > > -
> > > >     mutex_lock(&mgr->lock);
> > > > -   send_remove =
> > > drm_dp_mst_port_downstream_of_branch(new_payload->port, mgr-
> > > > mst_primary);
> > > > +   send_remove = drm_dp_mst_port_downstream_of_branch(payload-
> > > > port,
> > > > +mgr->mst_primary);
> > > >     mutex_unlock(&mgr->lock);
> > > >
> > > >     if (send_remove)
> > > > -           drm_dp_destroy_payload_step1(mgr, mst_state,
> > > new_payload);
> > > > +           drm_dp_destroy_payload_at_remote_and_dfp(mgr,
> > > mst_state, payload);
> > > >     else
> > > >             drm_dbg_kms(mgr->dev, "Payload for VCPI %d not in
> > > topology, not sending remove\n",
> > > > -                       new_payload->vcpi);
> > > > +                       payload->vcpi);
> > > > +
> > > > +   payload->payload_allocation_status =
> > > > +DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL;
> > > > +}
> > > > +EXPORT_SYMBOL(drm_dp_remove_payload_part1);
> > > >
> > > > +/**
> > > > + * drm_dp_remove_payload_part2() - Remove an MST payload locally
> > > > + * @mgr: Manager to use.
> > > > + * @mst_state: The MST atomic state
> > > > + * @old_payload: The payload with its old state
> > > > + * @new_payload: The payload with its latest state
> > > > + *
> > > > + * Updates the starting time slots of all other payloads which
> > > > +would have been shifted towards
> > > > + * the start of the payload ID table as a result of removing a
> > > > +payload. Driver should call this
> > > > + * function whenever it removes a payload in its HW. It's
> > > > +independent to the result of payload
> > > > + * allocation/deallocation at branch devices along the virtual channel.
> > > > + */
> > > > +void drm_dp_remove_payload_part2(struct
> drm_dp_mst_topology_mgr
> > > *mgr,
> > > > +                            struct drm_dp_mst_topology_state
> > > *mst_state,
> > > > +                            const struct
> > > > + drm_dp_mst_atomic_payload
> > > *old_payload,
> > > > +                            struct drm_dp_mst_atomic_payload
> > > *new_payload) {
> > > > +   struct drm_dp_mst_atomic_payload *pos;
> > > > +
> > > > +   /* Remove local payload allocation */
> > > >     list_for_each_entry(pos, &mst_state->payloads, next) {
> > > >             if (pos != new_payload && pos->vc_start_slot >
> > > > new_payload-
> > > > vc_start_slot)
> > > >                     pos->vc_start_slot -= old_payload->time_slots;
> > > > @@ -
> > > 3382,9 +3409,10
> > > > @@ void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr
> > > *mgr,
> > > >
> > > >     if (new_payload->delete)
> > > >             drm_dp_mst_put_port_malloc(new_payload->port);
> > > > -}
> > > > -EXPORT_SYMBOL(drm_dp_remove_payload);
> > > >
> > > > +   new_payload->payload_allocation_status =
> > > > +DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
> > > > +}
> > > > +EXPORT_SYMBOL(drm_dp_remove_payload_part2);
> > > >  /**
> > > >   * drm_dp_add_payload_part2() - Execute payload update part 2
> > > >   * @mgr: Manager to use.
> > > > @@ -3403,17 +3431,19 @@ int drm_dp_add_payload_part2(struct
> > > drm_dp_mst_topology_mgr *mgr,
> > > >     int ret = 0;
> > > >
> > > >     /* Skip failed payloads */
> > > > -   if (payload->vc_start_slot == -1) {
> > > > -           drm_dbg_kms(mgr->dev, "Part 1 of payload creation for %s
> > > failed, skipping part 2\n",
> > > > +   if (payload->payload_allocation_status !=
> > > DRM_DP_MST_PAYLOAD_ALLOCATION_DFP) {
> > > > +           drm_dbg_kms(state->dev, "Part 1 of payload creation
> > > > + for %s
> > > failed,
> > > > +skipping part 2\n",
> > > >                         payload->port->connector->name);
> > > >             return -EIO;
> > > >     }
> > > >
> > > > -   ret = drm_dp_create_payload_step2(mgr, payload);
> > > > -   if (ret < 0) {
> > > > +   /* Allocate payload to remote end */
> > > > +   ret = drm_dp_create_payload_to_remote(mgr, payload);
> > > > +   if (ret < 0)
> > > >             drm_err(mgr->dev, "Step 2 of creating MST payload for
> > > > %p
> > > failed: %d\n",
> > > >                     payload->port, ret);
> > > > -   }
> > > > +   else
> > > > +           payload->payload_allocation_status =
> > > > +DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE;
> > > >
> > > >     return ret;
> > > >  }
> > > > @@ -4324,6 +4354,7 @@ int drm_dp_atomic_find_time_slots(struct
> > > drm_atomic_state *state,
> > > >             drm_dp_mst_get_port_malloc(port);
> > > >             payload->port = port;
> > > >             payload->vc_start_slot = -1;
> > > > +           payload->payload_allocation_status =
> > > > +DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
> > > >             list_add(&payload->next, &topology_state->payloads);
> > > >     }
> > > >     payload->time_slots = req_slots; @@ -4493,7 +4524,7 @@ void
> > > drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state
> > > *state)
> > > >             }
> > > >
> > > >             /* Now that previous state is committed, it's safe to
> > > > copy over
> > > the start slot
> > > > -            * assignments
> > > > +            * and allocation status assignments
> > > >              */
> > > >             list_for_each_entry(old_payload,
> > > > &old_mst_state->payloads,
> > > next) {
> > > >                     if (old_payload->delete) @@ -4502,6 +4533,8 @@
> > > > void
> > > drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state
> > > *state)
> > > >                     new_payload =
> > > drm_atomic_get_mst_payload_state(new_mst_state,
> > > >
> > > old_payload->port);
> > > >                     new_payload->vc_start_slot = old_payload-
> > > > vc_start_slot;
> > > > +                   new_payload->payload_allocation_status =
> > > > +                                                   old_payload-
> > > > payload_allocation_status;
> > >
> > > And here. Besides that, I think patches 1/3 and 2/3 look great! Just
> > > finished testing them on nouveau:
> > >
> > > Reviewed-by: Lyude Paul <lyude@redhat.com>
> > >
> > > Patch 3/3 I gotta think about a bit more (and am curious about
> > > Imre's current take on it) I think
> > >
> > > >             }
> > > >     }
> > > >  }
> > > > @@ -4818,6 +4851,13 @@ void drm_dp_mst_dump_topology(struct
> > > seq_file *m,
> > > >     struct drm_dp_mst_atomic_payload *payload;
> > > >     int i, ret;
> > > >
> > > > +   static const char *const status[] = {
> > > > +           "None",
> > > > +           "Local",
> > > > +           "DFP",
> > > > +           "Remote",
> > > > +   };
> > > > +
> > > >     mutex_lock(&mgr->lock);
> > > >     if (mgr->mst_primary)
> > > >             drm_dp_mst_dump_mstb(m, mgr->mst_primary); @@ -
> > > 4834,7 +4874,7 @@
> > > > void drm_dp_mst_dump_topology(struct seq_file *m,
> > > >     seq_printf(m, "payload_mask: %x, max_payloads: %d, start_slot:
> > > > %u,
> > > pbn_div: %d\n",
> > > >                state->payload_mask, mgr->max_payloads, state-
> > > > start_slot,
> > > > state->pbn_div);
> > > >
> > > > -   seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc |     sink name
> > > > \n");
> > > > +   seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc | status |     sink
> > > name     |\n");
> > > >     for (i = 0; i < mgr->max_payloads; i++) {
> > > >             list_for_each_entry(payload, &state->payloads, next) {
> > > >                     char name[14]; @@ -4843,7 +4883,7 @@ void
> > > > drm_dp_mst_dump_topology(struct
> > > seq_file *m,
> > > >                             continue;
> > > >
> > > >                     fetch_monitor_name(mgr, payload->port, name,
> > > sizeof(name));
> > > > -                   seq_printf(m, " %5d %6d %6d %02d - %02d %5d %5s
> > > %19s\n",
> > > > +                   seq_printf(m, " %5d %6d %6d %02d - %02d %5d
> > > > + %5s
> > > %8s %19s\n",
> > > >                                i,
> > > >                                payload->port->port_num,
> > > >                                payload->vcpi, @@ -4851,6 +4891,7
> > > > @@ void drm_dp_mst_dump_topology(struct
> > > seq_file *m,
> > > >                                payload->vc_start_slot + payload-
> > > > time_slots - 1,
> > > >                                payload->pbn,
> > > >                                payload->dsc_enabled ? "Y" : "N",
> > > > +
> > > > + status[payload->payload_allocation_status],
> > > >                                (*name != 0) ? name : "Unknown");
> > > >             }
> > > >     }
> > > > diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > > b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > > index e3f176a093d2..5f73cdabe7a1 100644
> > > > --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > > +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > > @@ -557,12 +557,8 @@ static void intel_mst_disable_dp(struct
> > > intel_atomic_state *state,
> > > >     struct intel_dp *intel_dp = &dig_port->dp;
> > > >     struct intel_connector *connector =
> > > >             to_intel_connector(old_conn_state->connector);
> > > > -   struct drm_dp_mst_topology_state *old_mst_state =
> > > > -           drm_atomic_get_old_mst_topology_state(&state->base,
> > > &intel_dp->mst_mgr);
> > > >     struct drm_dp_mst_topology_state *new_mst_state =
> > > >             drm_atomic_get_new_mst_topology_state(&state->base,
> > > &intel_dp->mst_mgr);
> > > > -   const struct drm_dp_mst_atomic_payload *old_payload =
> > > > -           drm_atomic_get_mst_payload_state(old_mst_state,
> > > connector->port);
> > > >     struct drm_dp_mst_atomic_payload *new_payload =
> > > >             drm_atomic_get_mst_payload_state(new_mst_state,
> > > connector->port);
> > > >     struct drm_i915_private *i915 = to_i915(connector->base.dev);
> > > > @@
> > > > -572,8 +568,7 @@ static void intel_mst_disable_dp(struct
> > > > intel_atomic_state *state,
> > > >
> > > >     intel_hdcp_disable(intel_mst->connector);
> > > >
> > > > -   drm_dp_remove_payload(&intel_dp->mst_mgr, new_mst_state,
> > > > -                         old_payload, new_payload);
> > > > +   drm_dp_remove_payload_part1(&intel_dp->mst_mgr,
> > > new_mst_state,
> > > > +new_payload);
> > > >
> > > >     intel_audio_codec_disable(encoder, old_crtc_state,
> > > > old_conn_state); } @@ -588,6 +583,14 @@ static void
> > > > intel_mst_post_disable_dp(struct intel_atomic_state *state,
> > > >     struct intel_dp *intel_dp = &dig_port->dp;
> > > >     struct intel_connector *connector =
> > > >             to_intel_connector(old_conn_state->connector);
> > > > +   struct drm_dp_mst_topology_state *old_mst_state =
> > > > +           drm_atomic_get_old_mst_topology_state(&state->base,
> > > &intel_dp->mst_mgr);
> > > > +   struct drm_dp_mst_topology_state *new_mst_state =
> > > > +           drm_atomic_get_new_mst_topology_state(&state->base,
> > > &intel_dp->mst_mgr);
> > > > +   const struct drm_dp_mst_atomic_payload *old_payload =
> > > > +           drm_atomic_get_mst_payload_state(old_mst_state,
> > > connector->port);
> > > > +   struct drm_dp_mst_atomic_payload *new_payload =
> > > > +           drm_atomic_get_mst_payload_state(new_mst_state,
> > > connector->port);
> > > >     struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
> > > >     bool last_mst_stream;
> > > >
> > > > @@ -608,6 +611,9 @@ static void intel_mst_post_disable_dp(struct
> > > > intel_atomic_state *state,
> > > >
> > > >     wait_for_act_sent(encoder, old_crtc_state);
> > > >
> > > > +   drm_dp_remove_payload_part2(&intel_dp->mst_mgr,
> > > new_mst_state,
> > > > +                               old_payload, new_payload);
> > > > +
> > > >     intel_ddi_disable_transcoder_func(old_crtc_state);
> > > >
> > > >     if (DISPLAY_VER(dev_priv) >= 9) diff --git
> > > > a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > > b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > > index 4e7c9c353c51..bba01fa0780c 100644
> > > > --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > > +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > > @@ -882,21 +882,26 @@ struct nouveau_encoder
> > > > *nv50_real_outp(struct drm_encoder *encoder)
> > > >
> > > >  static void
> > > >  nv50_msto_cleanup(struct drm_atomic_state *state,
> > > > -             struct drm_dp_mst_topology_state *mst_state,
> > > > +             struct drm_dp_mst_topology_state *new_mst_state,
> > > >               struct drm_dp_mst_topology_mgr *mgr,
> > > >               struct nv50_msto *msto)  {
> > > >     struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
> > > > -   struct drm_dp_mst_atomic_payload *payload =
> > > > -           drm_atomic_get_mst_payload_state(mst_state, msto->mstc-
> > > > port);
> > > > +   struct drm_dp_mst_atomic_payload *new_payload =
> > > > +           drm_atomic_get_mst_payload_state(new_mst_state, msto-
> > > > mstc->port);
> > > > +   struct drm_dp_mst_topology_state *old_mst_state =
> > > > +           drm_atomic_get_old_mst_topology_state(state, mgr);
> > > > +   const struct drm_dp_mst_atomic_payload *old_payload =
> > > > +           drm_atomic_get_mst_payload_state(old_mst_state, msto-
> > > > mstc->port);
> > > >
> > > >     NV_ATOMIC(drm, "%s: msto cleanup\n", msto->encoder.name);
> > > >
> > > >     if (msto->disabled) {
> > > >             msto->mstc = NULL;
> > > >             msto->disabled = false;
> > > > +           drm_dp_remove_payload_part2(mgr, new_mst_state,
> > > old_payload,
> > > > +new_payload);
> > > >     } else if (msto->enabled) {
> > > > -           drm_dp_add_payload_part2(mgr, state, payload);
> > > > +           drm_dp_add_payload_part2(mgr, state, new_payload);
> > > >             msto->enabled = false;
> > > >     }
> > > >  }
> > > > @@ -910,19 +915,15 @@ nv50_msto_prepare(struct drm_atomic_state
> > > *state,
> > > >     struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
> > > >     struct nv50_mstc *mstc = msto->mstc;
> > > >     struct nv50_mstm *mstm = mstc->mstm;
> > > > -   struct drm_dp_mst_topology_state *old_mst_state;
> > > > -   struct drm_dp_mst_atomic_payload *payload, *old_payload;
> > > > +   struct drm_dp_mst_atomic_payload *payload;
> > > >
> > > >     NV_ATOMIC(drm, "%s: msto prepare\n", msto->encoder.name);
> > > >
> > > > -   old_mst_state = drm_atomic_get_old_mst_topology_state(state,
> > > mgr);
> > > > -
> > > >     payload = drm_atomic_get_mst_payload_state(mst_state, mstc-
> > > > port);
> > > > -   old_payload = drm_atomic_get_mst_payload_state(old_mst_state,
> > > mstc->port);
> > > >
> > > >     // TODO: Figure out if we want to do a better job of handling
> > > > VCPI
> > > allocation failures here?
> > > >     if (msto->disabled) {
> > > > -           drm_dp_remove_payload(mgr, mst_state, old_payload,
> > > payload);
> > > > +           drm_dp_remove_payload_part1(mgr, mst_state, payload);
> > > >
> > > >             nvif_outp_dp_mst_vcpi(&mstm->outp->outp, msto->head-
> > > > base.index, 0, 0, 0, 0);
> > > >     } else {
> > > > diff --git a/include/drm/display/drm_dp_mst_helper.h
> > > > b/include/drm/display/drm_dp_mst_helper.h
> > > > index ed5c9660563c..4429d3b1745b 100644
> > > > --- a/include/drm/display/drm_dp_mst_helper.h
> > > > +++ b/include/drm/display/drm_dp_mst_helper.h
> > > > @@ -46,6 +46,13 @@ struct drm_dp_mst_topology_ref_history {  };
> > > > #endif /*
> IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) */
> > > >
> > > > +enum drm_dp_mst_payload_allocation {
> > > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_NONE,
> > > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL,
> > > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_DFP,
> > > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE,
> > > > +};
> > > > +
> > > >  struct drm_dp_mst_branch;
> > > >
> > > >  /**
> > > > @@ -537,7 +544,7 @@ struct drm_dp_mst_atomic_payload {
> > > >      *   drm_dp_mst_atomic_wait_for_dependencies() has been called,
> > > which will ensure the
> > > >      *   previous MST states payload start slots have been copied over to
> > > the new state. Note
> > > >      *   that a new start slot won't be assigned/removed from this payload
> > > until
> > > > -    *   drm_dp_add_payload_part1()/drm_dp_remove_payload() have
> > > been called.
> > > > +    *   drm_dp_add_payload_part1()/drm_dp_remove_payload_part2()
> > > have been called.
> > > >      * * Acquire the MST modesetting lock, and then wait for any
> > > > pending
> > > MST-related commits to
> > > >      *   get committed to hardware by calling drm_crtc_commit_wait() on
> > > each of the
> > > >      *   &drm_crtc_commit structs in
> > > &drm_dp_mst_topology_state.commit_deps.
> > > > @@ -564,6 +571,9 @@ struct drm_dp_mst_atomic_payload {
> > > >     /** @dsc_enabled: Whether or not this payload has DSC enabled */
> > > >     bool dsc_enabled : 1;
> > > >
> > > > +   /** @payload_allocation_status: The allocation status of this
> > > > + payload
> > > */
> > > > +   enum drm_dp_mst_payload_allocation payload_allocation_status;
> > > > +
> > > >     /** @next: The list node for this payload */
> > > >     struct list_head next;
> > > >  };
> > > > @@ -842,10 +852,13 @@ int drm_dp_add_payload_part1(struct
> > > > drm_dp_mst_topology_mgr *mgr,  int
> drm_dp_add_payload_part2(struct
> > > drm_dp_mst_topology_mgr *mgr,
> > > >                          struct drm_atomic_state *state,
> > > >                          struct drm_dp_mst_atomic_payload
> > > > *payload); -
> > > void
> > > > drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
> > > > -                      struct drm_dp_mst_topology_state *mst_state,
> > > > -                      const struct drm_dp_mst_atomic_payload
> > > *old_payload,
> > > > -                      struct drm_dp_mst_atomic_payload
> > > *new_payload);
> > > > +void drm_dp_remove_payload_part1(struct
> drm_dp_mst_topology_mgr
> > > *mgr,
> > > > +                            struct drm_dp_mst_topology_state
> > > *mst_state,
> > > > +                            struct drm_dp_mst_atomic_payload
> > > *payload); void
> > > > +drm_dp_remove_payload_part2(struct drm_dp_mst_topology_mgr
> *mgr,
> > > > +                            struct drm_dp_mst_topology_state
> > > *mst_state,
> > > > +                            const struct
> > > > + drm_dp_mst_atomic_payload
> > > *old_payload,
> > > > +                            struct drm_dp_mst_atomic_payload
> > > *new_payload);
> > > >
> > > >  int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr);
> > > >
> > >
> > > --
> > > Cheers,
> > >  Lyude Paul (she/her)
> > >  Software Engineer at Red Hat
> > --
> > Regards,
> > Wayne
>
> --
> Cheers,
>  Lyude Paul (she/her)
>  Software Engineer at Red Hat
--
Regards,
Wayne

Re: [Patch v2 2/3] drm/mst: Refactor the flow for payload allocation/removement

[Lyude Paul]

On Thu, 2023-08-24 at 04:12 +0000, Lin, Wayne wrote:
> [Public]
> 
> Hi Lyude,
> 
> I'm afraid that I don't have the permissions to push and would like to have
> your help. Thanks!

Whoops, sorry I only just noticed this message. I set a reminder on my phone
to bug me to push it tomorrow :), sorry about the delay

> 
> > -----Original Message-----
> > From: Lyude Paul <lyude@redhat.com>
> > Sent: Thursday, August 24, 2023 5:00 AM
> > To: Lin, Wayne <Wayne.Lin@amd.com>; dri-devel@lists.freedesktop.org;
> > amd-gfx@lists.freedesktop.org
> > Cc: jani.nikula@intel.com; ville.syrjala@linux.intel.com; imre.deak@intel.com;
> > Wentland, Harry <Harry.Wentland@amd.com>; Zuo, Jerry
> > <Jerry.Zuo@amd.com>
> > Subject: Re: [Patch v2 2/3] drm/mst: Refactor the flow for payload
> > allocation/removement
> > 
> > Sure - you're also welcome to push the first two patches after fixing the
> > indentation if you'd like
> > 
> > On Wed, 2023-08-23 at 03:19 +0000, Lin, Wayne wrote:
> > > [Public]
> > > 
> > > Thanks, Lyude!
> > > Should I push another version to fix the indention?
> > > 
> > > > -----Original Message-----
> > > > From: Lyude Paul <lyude@redhat.com>
> > > > Sent: Friday, August 18, 2023 6:17 AM
> > > > To: Lin, Wayne <Wayne.Lin@amd.com>; dri-devel@lists.freedesktop.org;
> > > > amd-gfx@lists.freedesktop.org
> > > > Cc: jani.nikula@intel.com; ville.syrjala@linux.intel.com;
> > > > imre.deak@intel.com; Wentland, Harry <Harry.Wentland@amd.com>; Zuo,
> > > > Jerry <Jerry.Zuo@amd.com>
> > > > Subject: Re: [Patch v2 2/3] drm/mst: Refactor the flow for payload
> > > > allocation/removement
> > > > 
> > > > Two small comments:
> > > > 
> > > > On Mon, 2023-08-07 at 10:56 +0800, Wayne Lin wrote:
> > > > > [Why]
> > > > > Today, the allocation/deallocation steps and status is a bit unclear.
> > > > > 
> > > > > For instance, payload->vc_start_slot = -1 stands for "the failure
> > > > > of updating DPCD payload ID table" and can also represent as
> > > > > "payload is not allocated yet". These two cases should be handled
> > > > > differently and hence better to distinguish them for better understanding.
> > > > > 
> > > > > [How]
> > > > > Define enumeration - ALLOCATION_LOCAL, ALLOCATION_DFP and
> > > > > ALLOCATION_REMOTE to distinguish different allocation status.
> > > > > Adjust the code to handle different status accordingly for better
> > > > > understanding the sequence of payload allocation and payload
> > > > removement.
> > > > > 
> > > > > For payload creation, the procedure should look like this:
> > > > > DRM part 1:
> > > > > * step 1 - update sw mst mgr variables to add a new payload
> > > > > * step 2 - add payload at immediate DFP DPCD payload table
> > > > > 
> > > > > Driver:
> > > > > * Add new payload in HW and sync up with DFP by sending ACT
> > > > > 
> > > > > DRM Part 2:
> > > > > * Send ALLOCATE_PAYLOAD sideband message to allocate bandwidth
> > > > > along
> > > > the
> > > > >   virtual channel.
> > > > > 
> > > > > And as for payload removement, the procedure should look like this:
> > > > > DRM part 1:
> > > > > * step 1 - Send ALLOCATE_PAYLOAD sideband message to release
> > bandwidth
> > > > >            along the virtual channel
> > > > > * step 2 - Clear payload allocation at immediate DFP DPCD payload
> > > > > table
> > > > > 
> > > > > Driver:
> > > > > * Remove the payload in HW and sync up with DFP by sending ACT
> > > > > 
> > > > > DRM part 2:
> > > > > * update sw mst mgr variables to remove the payload
> > > > > 
> > > > > Note that it's fine to fail when communicate with the branch
> > > > > device connected at immediate downstrean-facing port, but updating
> > > > > variables of SW mst mgr and HW configuration should be conducted
> > > > > anyway. That's because it's under commit_tail and we need to
> > > > > complete the HW
> > > > programming.
> > > > > 
> > > > > Changes since v1:
> > > > > * Remove the set but not use variable 'old_payload' in function
> > > > >   'nv50_msto_prepare'. Catched by kernel test robot
> > > > > <lkp@intel.com>
> > > > > 
> > > > > Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
> > > > > ---
> > > > >  .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  20 ++-
> > > > > drivers/gpu/drm/display/drm_dp_mst_topology.c | 159
> > > > > +++++++++++------
> > > > -
> > > > >  drivers/gpu/drm/i915/display/intel_dp_mst.c   |  18 +-
> > > > >  drivers/gpu/drm/nouveau/dispnv50/disp.c       |  21 +--
> > > > >  include/drm/display/drm_dp_mst_helper.h       |  23 ++-
> > > > >  5 files changed, 153 insertions(+), 88 deletions(-)
> > > > > 
> > > > > diff --git
> > > > a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > > > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > > > index d9a482908380..9ad509279b0a 100644
> > > > > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > > > +++
> > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > > > @@ -219,7 +219,7 @@ static void dm_helpers_construct_old_payload(
> > > > >     /* Set correct time_slots/PBN of old payload.
> > > > >      * other fields (delete & dsc_enabled) in
> > > > >      * struct drm_dp_mst_atomic_payload are don't care fields
> > > > > -    * while calling drm_dp_remove_payload()
> > > > > +    * while calling drm_dp_remove_payload_part2()
> > > > >      */
> > > > >     for (i = 0; i < current_link_table.stream_count; i++) {
> > > > >             dc_alloc =
> > > > > @@ -262,13 +262,12 @@ bool
> > > > > dm_helpers_dp_mst_write_payload_allocation_table(
> > > > > 
> > > > >     mst_mgr = &aconnector->mst_root->mst_mgr;
> > > > >     mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
> > > > > -
> > > > > -   /* It's OK for this to fail */
> > > > >     new_payload = drm_atomic_get_mst_payload_state(mst_state,
> > > > > aconnector->mst_output_port);
> > > > > 
> > > > >     if (enable) {
> > > > >             target_payload = new_payload;
> > > > > 
> > > > > +           /* It's OK for this to fail */
> > > > >             drm_dp_add_payload_part1(mst_mgr, mst_state,
> > > > new_payload);
> > > > >     } else {
> > > > >             /* construct old payload by VCPI*/ @@ -276,7 +275,7 @@
> > > > > bool
> > > > dm_helpers_dp_mst_write_payload_allocation_table(
> > > > >                                             new_payload, &old_payload);
> > > > >             target_payload = &old_payload;
> > > > > 
> > > > > -           drm_dp_remove_payload(mst_mgr, mst_state,
> > > > &old_payload, new_payload);
> > > > > +           drm_dp_remove_payload_part1(mst_mgr, mst_state,
> > > > new_payload);
> > > > >     }
> > > > > 
> > > > >     /* mst_mgr->->payloads are VC payload notify MST branch using
> > > > DPCD
> > > > > or @@ -342,7 +341,7 @@ bool
> > > > dm_helpers_dp_mst_send_payload_allocation(
> > > > >     struct amdgpu_dm_connector *aconnector;
> > > > >     struct drm_dp_mst_topology_state *mst_state;
> > > > >     struct drm_dp_mst_topology_mgr *mst_mgr;
> > > > > -   struct drm_dp_mst_atomic_payload *payload;
> > > > > +   struct drm_dp_mst_atomic_payload *new_payload, *old_payload;
> > > > >     enum mst_progress_status set_flag =
> > > > MST_ALLOCATE_NEW_PAYLOAD;
> > > > >     enum mst_progress_status clr_flag =
> > > > MST_CLEAR_ALLOCATED_PAYLOAD;
> > > > >     int ret = 0;
> > > > > @@ -355,15 +354,20 @@ bool
> > > > dm_helpers_dp_mst_send_payload_allocation(
> > > > >     mst_mgr = &aconnector->mst_root->mst_mgr;
> > > > >     mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
> > > > > 
> > > > > -   payload = drm_atomic_get_mst_payload_state(mst_state,
> > > > aconnector->mst_output_port);
> > > > > +   new_payload = drm_atomic_get_mst_payload_state(mst_state,
> > > > > +aconnector->mst_output_port);
> > > > > 
> > > > >     if (!enable) {
> > > > >             set_flag = MST_CLEAR_ALLOCATED_PAYLOAD;
> > > > >             clr_flag = MST_ALLOCATE_NEW_PAYLOAD;
> > > > >     }
> > > > > 
> > > > > -   if (enable)
> > > > > -           ret = drm_dp_add_payload_part2(mst_mgr, mst_state-
> > > > > base.state, payload);
> > > > > +   if (enable) {
> > > > > +           ret = drm_dp_add_payload_part2(mst_mgr, mst_state-
> > > > > base.state, new_payload);
> > > > > +   } else {
> > > > > +           dm_helpers_construct_old_payload(stream->link,
> > > > > + mst_state-
> > > > > pbn_div,
> > > > > +                                            new_payload, old_payload);
> > > > > +           drm_dp_remove_payload_part2(mst_mgr, mst_state,
> > > > old_payload, new_payload);
> > > > > +   }
> > > > > 
> > > > >     if (ret) {
> > > > >             amdgpu_dm_set_mst_status(&aconnector->mst_status,
> > > > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > > > b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > > > index 4d80426757ab..e04f87ff755a 100644
> > > > > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > > > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > > > @@ -3255,15 +3255,15 @@ int
> > > > drm_dp_send_query_stream_enc_status(struct
> > > > > drm_dp_mst_topology_mgr *mgr,  }
> > > > > EXPORT_SYMBOL(drm_dp_send_query_stream_enc_status);
> > > > > 
> > > > > -static int drm_dp_create_payload_step1(struct
> > > > > drm_dp_mst_topology_mgr
> > > > *mgr,
> > > > > -                                  struct drm_dp_mst_atomic_payload
> > > > *payload)
> > > > > +static int drm_dp_create_payload_at_dfp(struct
> > > > drm_dp_mst_topology_mgr *mgr,
> > > > > +                                   struct
> > > > > + drm_dp_mst_atomic_payload
> > > > *payload)
> > > > >  {
> > > > >     return drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload-
> > > > > vc_start_slot,
> > > > >                                      payload->time_slots);  }
> > > > > 
> > > > > -static int drm_dp_create_payload_step2(struct
> > > > > drm_dp_mst_topology_mgr
> > > > *mgr,
> > > > > -                                  struct drm_dp_mst_atomic_payload
> > > > *payload)
> > > > > +static int drm_dp_create_payload_to_remote(struct
> > > > drm_dp_mst_topology_mgr *mgr,
> > > > > +                                      struct
> > > > > + drm_dp_mst_atomic_payload
> > > > *payload)
> > > > >  {
> > > > >     int ret;
> > > > >     struct drm_dp_mst_port *port =
> > > > > drm_dp_mst_topology_get_port_validated(mgr, payload->port); @@ -
> > > > 3276,17 +3276,20 @@ static int drm_dp_create_payload_step2(struct
> > > > drm_dp_mst_topology_mgr *mgr,
> > > > >     return ret;
> > > > >  }
> > > > > 
> > > > > -static int drm_dp_destroy_payload_step1(struct
> > > > drm_dp_mst_topology_mgr *mgr,
> > > > > -                                   struct drm_dp_mst_topology_state
> > > > *mst_state,
> > > > > -                                   struct drm_dp_mst_atomic_payload
> > > > *payload)
> > > > > +static void drm_dp_destroy_payload_at_remote_and_dfp(struct
> > > > drm_dp_mst_topology_mgr *mgr,
> > > > > +                                                struct
> > > > drm_dp_mst_topology_state *mst_state,
> > > > > +                                                struct
> > > > drm_dp_mst_atomic_payload *payload)
> > > > >  {
> > > > >     drm_dbg_kms(mgr->dev, "\n");
> > > > > 
> > > > >     /* it's okay for these to fail */
> > > > > -   drm_dp_payload_send_msg(mgr, payload->port, payload->vcpi, 0);
> > > > > -   drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload-
> > > > > vc_start_slot, 0);
> > > > > +   if (payload->payload_allocation_status ==
> > > > DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE) {
> > > > > +           drm_dp_payload_send_msg(mgr, payload->port, payload-
> > > > > vcpi, 0);
> > > > > +           payload->payload_allocation_status =
> > > > DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
> > > > > +   }
> > > > > 
> > > > > -   return 0;
> > > > > +   if (payload->payload_allocation_status ==
> > > > DRM_DP_MST_PAYLOAD_ALLOCATION_DFP)
> > > > > +           drm_dp_dpcd_write_payload(mgr, payload->vcpi,
> > > > > +payload->vc_start_slot, 0);
> > > > >  }
> > > > > 
> > > > >  /**
> > > > > @@ -3296,81 +3299,105 @@ static int
> > > > drm_dp_destroy_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
> > > > >   * @payload: The payload to write
> > > > >   *
> > > > >   * Determines the starting time slot for the given payload, and
> > > > > programs the VCPI for this payload
> > > > > - * into hardware. After calling this, the driver should generate
> > > > > ACT and
> > > > payload packets.
> > > > > + * into the DPCD of DPRX. After calling this, the driver should
> > > > > + generate ACT
> > > > and payload packets.
> > > > >   *
> > > > > - * Returns: 0 on success, error code on failure. In the event
> > > > > that this fails,
> > > > > - * @payload.vc_start_slot will also be set to -1.
> > > > > + * Returns: 0 on success, error code on failure.
> > > > >   */
> > > > >  int drm_dp_add_payload_part1(struct drm_dp_mst_topology_mgr
> > *mgr,
> > > > >                          struct drm_dp_mst_topology_state *mst_state,
> > > > >                          struct drm_dp_mst_atomic_payload *payload)  {
> > > > >     struct drm_dp_mst_port *port;
> > > > > -   int ret;
> > > > > +   int ret = 0;
> > > > > +   bool allocate = true;
> > > > > +
> > > > > +   /* Update mst mgr info */
> > > > > +   if (mgr->payload_count == 0)
> > > > > +           mgr->next_start_slot = mst_state->start_slot;
> > > > > +
> > > > > +   payload->vc_start_slot = mgr->next_start_slot;
> > > > > +
> > > > > +   mgr->payload_count++;
> > > > > +   mgr->next_start_slot += payload->time_slots;
> > > > > 
> > > > > +   /* Allocate payload to immediate downstream facing port */
> > > > >     port = drm_dp_mst_topology_get_port_validated(mgr, payload-
> > > > > port);
> > > > >     if (!port) {
> > > > >             drm_dbg_kms(mgr->dev,
> > > > > -                       "VCPI %d for port %p not in topology, not creating a
> > > > payload\n",
> > > > > +                       "VCPI %d for port %p not in topology, not
> > > > > + creating a
> > > > payload
> > > > > +to remote\n",
> > > > >                         payload->vcpi, payload->port);
> > > > > -           payload->vc_start_slot = -1;
> > > > > -           return 0;
> > > > > +           allocate = false;
> > > > >     }
> > > > > 
> > > > > -   if (mgr->payload_count == 0)
> > > > > -           mgr->next_start_slot = mst_state->start_slot;
> > > > > -
> > > > > -   payload->vc_start_slot = mgr->next_start_slot;
> > > > > +   if (allocate) {
> > > > > +           ret = drm_dp_create_payload_at_dfp(mgr, payload);
> > > > > +           if (ret < 0)
> > > > > +                   drm_warn(mgr->dev, "Failed to create MST
> > > > > + payload
> > > > for port %p: %d\n",
> > > > > +                            payload->port, ret);
> > > > > 
> > > > > -   ret = drm_dp_create_payload_step1(mgr, payload);
> > > > > -   drm_dp_mst_topology_put_port(port);
> > > > > -   if (ret < 0) {
> > > > > -           drm_warn(mgr->dev, "Failed to create MST payload for port
> > > > %p: %d\n",
> > > > > -                    payload->port, ret);
> > > > > -           payload->vc_start_slot = -1;
> > > > > -           return ret;
> > > > >     }
> > > > > 
> > > > > -   mgr->payload_count++;
> > > > > -   mgr->next_start_slot += payload->time_slots;
> > > > > +   payload->payload_allocation_status =
> > > > > +           (!allocate || ret < 0) ?
> > > > DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL :
> > > > > +
> > > >       DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
> > > > 
> > > > Just need to fix indenting here
> > > > 
> > > > > 
> > > > > -   return 0;
> > > > > +   drm_dp_mst_topology_put_port(port);
> > > > > +
> > > > > +   return ret;
> > > > >  }
> > > > >  EXPORT_SYMBOL(drm_dp_add_payload_part1);
> > > > > 
> > > > >  /**
> > > > > - * drm_dp_remove_payload() - Remove an MST payload
> > > > > + * drm_dp_remove_payload_part1() - Remove an MST payload along
> > > > > + the virtual channel
> > > > >   * @mgr: Manager to use.
> > > > >   * @mst_state: The MST atomic state
> > > > > - * @old_payload: The payload with its old state
> > > > > - * @new_payload: The payload to write
> > > > > + * @payload: The payload to remove
> > > > >   *
> > > > > - * Removes a payload from an MST topology if it was successfully
> > > > > assigned a start slot. Also updates
> > > > > - * the starting time slots of all other payloads which would have
> > > > > been shifted towards the start of
> > > > > - * the VC table as a result. After calling this, the driver
> > > > > should generate ACT
> > > > and payload packets.
> > > > > + * Removes a payload along the virtual channel if it was
> > > > > + successfully
> > > > allocated.
> > > > > + * After calling this, the driver should set HW to generate ACT
> > > > > + and then switch to new
> > > > > + * payload allocation state.
> > > > >   */
> > > > > -void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
> > > > > -                      struct drm_dp_mst_topology_state *mst_state,
> > > > > -                      const struct drm_dp_mst_atomic_payload
> > > > *old_payload,
> > > > > -                      struct drm_dp_mst_atomic_payload *new_payload)
> > > > > +void drm_dp_remove_payload_part1(struct
> > drm_dp_mst_topology_mgr
> > > > *mgr,
> > > > > +                            struct drm_dp_mst_topology_state
> > > > *mst_state,
> > > > > +                            struct drm_dp_mst_atomic_payload
> > > > *payload)
> > > > >  {
> > > > > -   struct drm_dp_mst_atomic_payload *pos;
> > > > > +   /* Remove remote payload allocation */
> > > > >     bool send_remove = false;
> > > > > 
> > > > > -   /* We failed to make the payload, so nothing to do */
> > > > > -   if (new_payload->vc_start_slot == -1)
> > > > > -           return;
> > > > > -
> > > > >     mutex_lock(&mgr->lock);
> > > > > -   send_remove =
> > > > drm_dp_mst_port_downstream_of_branch(new_payload->port, mgr-
> > > > > mst_primary);
> > > > > +   send_remove = drm_dp_mst_port_downstream_of_branch(payload-
> > > > > port,
> > > > > +mgr->mst_primary);
> > > > >     mutex_unlock(&mgr->lock);
> > > > > 
> > > > >     if (send_remove)
> > > > > -           drm_dp_destroy_payload_step1(mgr, mst_state,
> > > > new_payload);
> > > > > +           drm_dp_destroy_payload_at_remote_and_dfp(mgr,
> > > > mst_state, payload);
> > > > >     else
> > > > >             drm_dbg_kms(mgr->dev, "Payload for VCPI %d not in
> > > > topology, not sending remove\n",
> > > > > -                       new_payload->vcpi);
> > > > > +                       payload->vcpi);
> > > > > +
> > > > > +   payload->payload_allocation_status =
> > > > > +DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL;
> > > > > +}
> > > > > +EXPORT_SYMBOL(drm_dp_remove_payload_part1);
> > > > > 
> > > > > +/**
> > > > > + * drm_dp_remove_payload_part2() - Remove an MST payload locally
> > > > > + * @mgr: Manager to use.
> > > > > + * @mst_state: The MST atomic state
> > > > > + * @old_payload: The payload with its old state
> > > > > + * @new_payload: The payload with its latest state
> > > > > + *
> > > > > + * Updates the starting time slots of all other payloads which
> > > > > +would have been shifted towards
> > > > > + * the start of the payload ID table as a result of removing a
> > > > > +payload. Driver should call this
> > > > > + * function whenever it removes a payload in its HW. It's
> > > > > +independent to the result of payload
> > > > > + * allocation/deallocation at branch devices along the virtual channel.
> > > > > + */
> > > > > +void drm_dp_remove_payload_part2(struct
> > drm_dp_mst_topology_mgr
> > > > *mgr,
> > > > > +                            struct drm_dp_mst_topology_state
> > > > *mst_state,
> > > > > +                            const struct
> > > > > + drm_dp_mst_atomic_payload
> > > > *old_payload,
> > > > > +                            struct drm_dp_mst_atomic_payload
> > > > *new_payload) {
> > > > > +   struct drm_dp_mst_atomic_payload *pos;
> > > > > +
> > > > > +   /* Remove local payload allocation */
> > > > >     list_for_each_entry(pos, &mst_state->payloads, next) {
> > > > >             if (pos != new_payload && pos->vc_start_slot >
> > > > > new_payload-
> > > > > vc_start_slot)
> > > > >                     pos->vc_start_slot -= old_payload->time_slots;
> > > > > @@ -
> > > > 3382,9 +3409,10
> > > > > @@ void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr
> > > > *mgr,
> > > > > 
> > > > >     if (new_payload->delete)
> > > > >             drm_dp_mst_put_port_malloc(new_payload->port);
> > > > > -}
> > > > > -EXPORT_SYMBOL(drm_dp_remove_payload);
> > > > > 
> > > > > +   new_payload->payload_allocation_status =
> > > > > +DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
> > > > > +}
> > > > > +EXPORT_SYMBOL(drm_dp_remove_payload_part2);
> > > > >  /**
> > > > >   * drm_dp_add_payload_part2() - Execute payload update part 2
> > > > >   * @mgr: Manager to use.
> > > > > @@ -3403,17 +3431,19 @@ int drm_dp_add_payload_part2(struct
> > > > drm_dp_mst_topology_mgr *mgr,
> > > > >     int ret = 0;
> > > > > 
> > > > >     /* Skip failed payloads */
> > > > > -   if (payload->vc_start_slot == -1) {
> > > > > -           drm_dbg_kms(mgr->dev, "Part 1 of payload creation for %s
> > > > failed, skipping part 2\n",
> > > > > +   if (payload->payload_allocation_status !=
> > > > DRM_DP_MST_PAYLOAD_ALLOCATION_DFP) {
> > > > > +           drm_dbg_kms(state->dev, "Part 1 of payload creation
> > > > > + for %s
> > > > failed,
> > > > > +skipping part 2\n",
> > > > >                         payload->port->connector->name);
> > > > >             return -EIO;
> > > > >     }
> > > > > 
> > > > > -   ret = drm_dp_create_payload_step2(mgr, payload);
> > > > > -   if (ret < 0) {
> > > > > +   /* Allocate payload to remote end */
> > > > > +   ret = drm_dp_create_payload_to_remote(mgr, payload);
> > > > > +   if (ret < 0)
> > > > >             drm_err(mgr->dev, "Step 2 of creating MST payload for
> > > > > %p
> > > > failed: %d\n",
> > > > >                     payload->port, ret);
> > > > > -   }
> > > > > +   else
> > > > > +           payload->payload_allocation_status =
> > > > > +DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE;
> > > > > 
> > > > >     return ret;
> > > > >  }
> > > > > @@ -4324,6 +4354,7 @@ int drm_dp_atomic_find_time_slots(struct
> > > > drm_atomic_state *state,
> > > > >             drm_dp_mst_get_port_malloc(port);
> > > > >             payload->port = port;
> > > > >             payload->vc_start_slot = -1;
> > > > > +           payload->payload_allocation_status =
> > > > > +DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
> > > > >             list_add(&payload->next, &topology_state->payloads);
> > > > >     }
> > > > >     payload->time_slots = req_slots; @@ -4493,7 +4524,7 @@ void
> > > > drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state
> > > > *state)
> > > > >             }
> > > > > 
> > > > >             /* Now that previous state is committed, it's safe to
> > > > > copy over
> > > > the start slot
> > > > > -            * assignments
> > > > > +            * and allocation status assignments
> > > > >              */
> > > > >             list_for_each_entry(old_payload,
> > > > > &old_mst_state->payloads,
> > > > next) {
> > > > >                     if (old_payload->delete) @@ -4502,6 +4533,8 @@
> > > > > void
> > > > drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state
> > > > *state)
> > > > >                     new_payload =
> > > > drm_atomic_get_mst_payload_state(new_mst_state,
> > > > > 
> > > > old_payload->port);
> > > > >                     new_payload->vc_start_slot = old_payload-
> > > > > vc_start_slot;
> > > > > +                   new_payload->payload_allocation_status =
> > > > > +                                                   old_payload-
> > > > > payload_allocation_status;
> > > > 
> > > > And here. Besides that, I think patches 1/3 and 2/3 look great! Just
> > > > finished testing them on nouveau:
> > > > 
> > > > Reviewed-by: Lyude Paul <lyude@redhat.com>
> > > > 
> > > > Patch 3/3 I gotta think about a bit more (and am curious about
> > > > Imre's current take on it) I think
> > > > 
> > > > >             }
> > > > >     }
> > > > >  }
> > > > > @@ -4818,6 +4851,13 @@ void drm_dp_mst_dump_topology(struct
> > > > seq_file *m,
> > > > >     struct drm_dp_mst_atomic_payload *payload;
> > > > >     int i, ret;
> > > > > 
> > > > > +   static const char *const status[] = {
> > > > > +           "None",
> > > > > +           "Local",
> > > > > +           "DFP",
> > > > > +           "Remote",
> > > > > +   };
> > > > > +
> > > > >     mutex_lock(&mgr->lock);
> > > > >     if (mgr->mst_primary)
> > > > >             drm_dp_mst_dump_mstb(m, mgr->mst_primary); @@ -
> > > > 4834,7 +4874,7 @@
> > > > > void drm_dp_mst_dump_topology(struct seq_file *m,
> > > > >     seq_printf(m, "payload_mask: %x, max_payloads: %d, start_slot:
> > > > > %u,
> > > > pbn_div: %d\n",
> > > > >                state->payload_mask, mgr->max_payloads, state-
> > > > > start_slot,
> > > > > state->pbn_div);
> > > > > 
> > > > > -   seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc |     sink name
> > > > > \n");
> > > > > +   seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc | status |     sink
> > > > name     |\n");
> > > > >     for (i = 0; i < mgr->max_payloads; i++) {
> > > > >             list_for_each_entry(payload, &state->payloads, next) {
> > > > >                     char name[14]; @@ -4843,7 +4883,7 @@ void
> > > > > drm_dp_mst_dump_topology(struct
> > > > seq_file *m,
> > > > >                             continue;
> > > > > 
> > > > >                     fetch_monitor_name(mgr, payload->port, name,
> > > > sizeof(name));
> > > > > -                   seq_printf(m, " %5d %6d %6d %02d - %02d %5d %5s
> > > > %19s\n",
> > > > > +                   seq_printf(m, " %5d %6d %6d %02d - %02d %5d
> > > > > + %5s
> > > > %8s %19s\n",
> > > > >                                i,
> > > > >                                payload->port->port_num,
> > > > >                                payload->vcpi, @@ -4851,6 +4891,7
> > > > > @@ void drm_dp_mst_dump_topology(struct
> > > > seq_file *m,
> > > > >                                payload->vc_start_slot + payload-
> > > > > time_slots - 1,
> > > > >                                payload->pbn,
> > > > >                                payload->dsc_enabled ? "Y" : "N",
> > > > > +
> > > > > + status[payload->payload_allocation_status],
> > > > >                                (*name != 0) ? name : "Unknown");
> > > > >             }
> > > > >     }
> > > > > diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > > > b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > > > index e3f176a093d2..5f73cdabe7a1 100644
> > > > > --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > > > +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > > > @@ -557,12 +557,8 @@ static void intel_mst_disable_dp(struct
> > > > intel_atomic_state *state,
> > > > >     struct intel_dp *intel_dp = &dig_port->dp;
> > > > >     struct intel_connector *connector =
> > > > >             to_intel_connector(old_conn_state->connector);
> > > > > -   struct drm_dp_mst_topology_state *old_mst_state =
> > > > > -           drm_atomic_get_old_mst_topology_state(&state->base,
> > > > &intel_dp->mst_mgr);
> > > > >     struct drm_dp_mst_topology_state *new_mst_state =
> > > > >             drm_atomic_get_new_mst_topology_state(&state->base,
> > > > &intel_dp->mst_mgr);
> > > > > -   const struct drm_dp_mst_atomic_payload *old_payload =
> > > > > -           drm_atomic_get_mst_payload_state(old_mst_state,
> > > > connector->port);
> > > > >     struct drm_dp_mst_atomic_payload *new_payload =
> > > > >             drm_atomic_get_mst_payload_state(new_mst_state,
> > > > connector->port);
> > > > >     struct drm_i915_private *i915 = to_i915(connector->base.dev);
> > > > > @@
> > > > > -572,8 +568,7 @@ static void intel_mst_disable_dp(struct
> > > > > intel_atomic_state *state,
> > > > > 
> > > > >     intel_hdcp_disable(intel_mst->connector);
> > > > > 
> > > > > -   drm_dp_remove_payload(&intel_dp->mst_mgr, new_mst_state,
> > > > > -                         old_payload, new_payload);
> > > > > +   drm_dp_remove_payload_part1(&intel_dp->mst_mgr,
> > > > new_mst_state,
> > > > > +new_payload);
> > > > > 
> > > > >     intel_audio_codec_disable(encoder, old_crtc_state,
> > > > > old_conn_state); } @@ -588,6 +583,14 @@ static void
> > > > > intel_mst_post_disable_dp(struct intel_atomic_state *state,
> > > > >     struct intel_dp *intel_dp = &dig_port->dp;
> > > > >     struct intel_connector *connector =
> > > > >             to_intel_connector(old_conn_state->connector);
> > > > > +   struct drm_dp_mst_topology_state *old_mst_state =
> > > > > +           drm_atomic_get_old_mst_topology_state(&state->base,
> > > > &intel_dp->mst_mgr);
> > > > > +   struct drm_dp_mst_topology_state *new_mst_state =
> > > > > +           drm_atomic_get_new_mst_topology_state(&state->base,
> > > > &intel_dp->mst_mgr);
> > > > > +   const struct drm_dp_mst_atomic_payload *old_payload =
> > > > > +           drm_atomic_get_mst_payload_state(old_mst_state,
> > > > connector->port);
> > > > > +   struct drm_dp_mst_atomic_payload *new_payload =
> > > > > +           drm_atomic_get_mst_payload_state(new_mst_state,
> > > > connector->port);
> > > > >     struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
> > > > >     bool last_mst_stream;
> > > > > 
> > > > > @@ -608,6 +611,9 @@ static void intel_mst_post_disable_dp(struct
> > > > > intel_atomic_state *state,
> > > > > 
> > > > >     wait_for_act_sent(encoder, old_crtc_state);
> > > > > 
> > > > > +   drm_dp_remove_payload_part2(&intel_dp->mst_mgr,
> > > > new_mst_state,
> > > > > +                               old_payload, new_payload);
> > > > > +
> > > > >     intel_ddi_disable_transcoder_func(old_crtc_state);
> > > > > 
> > > > >     if (DISPLAY_VER(dev_priv) >= 9) diff --git
> > > > > a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > > > b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > > > index 4e7c9c353c51..bba01fa0780c 100644
> > > > > --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > > > +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > > > @@ -882,21 +882,26 @@ struct nouveau_encoder
> > > > > *nv50_real_outp(struct drm_encoder *encoder)
> > > > > 
> > > > >  static void
> > > > >  nv50_msto_cleanup(struct drm_atomic_state *state,
> > > > > -             struct drm_dp_mst_topology_state *mst_state,
> > > > > +             struct drm_dp_mst_topology_state *new_mst_state,
> > > > >               struct drm_dp_mst_topology_mgr *mgr,
> > > > >               struct nv50_msto *msto)  {
> > > > >     struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
> > > > > -   struct drm_dp_mst_atomic_payload *payload =
> > > > > -           drm_atomic_get_mst_payload_state(mst_state, msto->mstc-
> > > > > port);
> > > > > +   struct drm_dp_mst_atomic_payload *new_payload =
> > > > > +           drm_atomic_get_mst_payload_state(new_mst_state, msto-
> > > > > mstc->port);
> > > > > +   struct drm_dp_mst_topology_state *old_mst_state =
> > > > > +           drm_atomic_get_old_mst_topology_state(state, mgr);
> > > > > +   const struct drm_dp_mst_atomic_payload *old_payload =
> > > > > +           drm_atomic_get_mst_payload_state(old_mst_state, msto-
> > > > > mstc->port);
> > > > > 
> > > > >     NV_ATOMIC(drm, "%s: msto cleanup\n", msto->encoder.name);
> > > > > 
> > > > >     if (msto->disabled) {
> > > > >             msto->mstc = NULL;
> > > > >             msto->disabled = false;
> > > > > +           drm_dp_remove_payload_part2(mgr, new_mst_state,
> > > > old_payload,
> > > > > +new_payload);
> > > > >     } else if (msto->enabled) {
> > > > > -           drm_dp_add_payload_part2(mgr, state, payload);
> > > > > +           drm_dp_add_payload_part2(mgr, state, new_payload);
> > > > >             msto->enabled = false;
> > > > >     }
> > > > >  }
> > > > > @@ -910,19 +915,15 @@ nv50_msto_prepare(struct drm_atomic_state
> > > > *state,
> > > > >     struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
> > > > >     struct nv50_mstc *mstc = msto->mstc;
> > > > >     struct nv50_mstm *mstm = mstc->mstm;
> > > > > -   struct drm_dp_mst_topology_state *old_mst_state;
> > > > > -   struct drm_dp_mst_atomic_payload *payload, *old_payload;
> > > > > +   struct drm_dp_mst_atomic_payload *payload;
> > > > > 
> > > > >     NV_ATOMIC(drm, "%s: msto prepare\n", msto->encoder.name);
> > > > > 
> > > > > -   old_mst_state = drm_atomic_get_old_mst_topology_state(state,
> > > > mgr);
> > > > > -
> > > > >     payload = drm_atomic_get_mst_payload_state(mst_state, mstc-
> > > > > port);
> > > > > -   old_payload = drm_atomic_get_mst_payload_state(old_mst_state,
> > > > mstc->port);
> > > > > 
> > > > >     // TODO: Figure out if we want to do a better job of handling
> > > > > VCPI
> > > > allocation failures here?
> > > > >     if (msto->disabled) {
> > > > > -           drm_dp_remove_payload(mgr, mst_state, old_payload,
> > > > payload);
> > > > > +           drm_dp_remove_payload_part1(mgr, mst_state, payload);
> > > > > 
> > > > >             nvif_outp_dp_mst_vcpi(&mstm->outp->outp, msto->head-
> > > > > base.index, 0, 0, 0, 0);
> > > > >     } else {
> > > > > diff --git a/include/drm/display/drm_dp_mst_helper.h
> > > > > b/include/drm/display/drm_dp_mst_helper.h
> > > > > index ed5c9660563c..4429d3b1745b 100644
> > > > > --- a/include/drm/display/drm_dp_mst_helper.h
> > > > > +++ b/include/drm/display/drm_dp_mst_helper.h
> > > > > @@ -46,6 +46,13 @@ struct drm_dp_mst_topology_ref_history {  };
> > > > > #endif /*
> > IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) */
> > > > > 
> > > > > +enum drm_dp_mst_payload_allocation {
> > > > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_NONE,
> > > > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL,
> > > > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_DFP,
> > > > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE,
> > > > > +};
> > > > > +
> > > > >  struct drm_dp_mst_branch;
> > > > > 
> > > > >  /**
> > > > > @@ -537,7 +544,7 @@ struct drm_dp_mst_atomic_payload {
> > > > >      *   drm_dp_mst_atomic_wait_for_dependencies() has been called,
> > > > which will ensure the
> > > > >      *   previous MST states payload start slots have been copied over to
> > > > the new state. Note
> > > > >      *   that a new start slot won't be assigned/removed from this payload
> > > > until
> > > > > -    *   drm_dp_add_payload_part1()/drm_dp_remove_payload() have
> > > > been called.
> > > > > +    *   drm_dp_add_payload_part1()/drm_dp_remove_payload_part2()
> > > > have been called.
> > > > >      * * Acquire the MST modesetting lock, and then wait for any
> > > > > pending
> > > > MST-related commits to
> > > > >      *   get committed to hardware by calling drm_crtc_commit_wait() on
> > > > each of the
> > > > >      *   &drm_crtc_commit structs in
> > > > &drm_dp_mst_topology_state.commit_deps.
> > > > > @@ -564,6 +571,9 @@ struct drm_dp_mst_atomic_payload {
> > > > >     /** @dsc_enabled: Whether or not this payload has DSC enabled */
> > > > >     bool dsc_enabled : 1;
> > > > > 
> > > > > +   /** @payload_allocation_status: The allocation status of this
> > > > > + payload
> > > > */
> > > > > +   enum drm_dp_mst_payload_allocation payload_allocation_status;
> > > > > +
> > > > >     /** @next: The list node for this payload */
> > > > >     struct list_head next;
> > > > >  };
> > > > > @@ -842,10 +852,13 @@ int drm_dp_add_payload_part1(struct
> > > > > drm_dp_mst_topology_mgr *mgr,  int
> > drm_dp_add_payload_part2(struct
> > > > drm_dp_mst_topology_mgr *mgr,
> > > > >                          struct drm_atomic_state *state,
> > > > >                          struct drm_dp_mst_atomic_payload
> > > > > *payload); -
> > > > void
> > > > > drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
> > > > > -                      struct drm_dp_mst_topology_state *mst_state,
> > > > > -                      const struct drm_dp_mst_atomic_payload
> > > > *old_payload,
> > > > > -                      struct drm_dp_mst_atomic_payload
> > > > *new_payload);
> > > > > +void drm_dp_remove_payload_part1(struct
> > drm_dp_mst_topology_mgr
> > > > *mgr,
> > > > > +                            struct drm_dp_mst_topology_state
> > > > *mst_state,
> > > > > +                            struct drm_dp_mst_atomic_payload
> > > > *payload); void
> > > > > +drm_dp_remove_payload_part2(struct drm_dp_mst_topology_mgr
> > *mgr,
> > > > > +                            struct drm_dp_mst_topology_state
> > > > *mst_state,
> > > > > +                            const struct
> > > > > + drm_dp_mst_atomic_payload
> > > > *old_payload,
> > > > > +                            struct drm_dp_mst_atomic_payload
> > > > *new_payload);
> > > > > 
> > > > >  int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr);
> > > > > 
> > > > 
> > > > --
> > > > Cheers,
> > > >  Lyude Paul (she/her)
> > > >  Software Engineer at Red Hat
> > > --
> > > Regards,
> > > Wayne
> > 
> > --
> > Cheers,
> >  Lyude Paul (she/her)
> >  Software Engineer at Red Hat
> --
> Regards,
> Wayne
> 

-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat

Re: [Patch v2 2/3] drm/mst: Refactor the flow for payload allocation/removement

[Alex Deucher]

On Thu, Aug 31, 2023 at 6:45 PM Lyude Paul <lyude@redhat.com> wrote:
>
> On Thu, 2023-08-24 at 04:12 +0000, Lin, Wayne wrote:
> > [Public]
> >
> > Hi Lyude,
> >
> > I'm afraid that I don't have the permissions to push and would like to have
> > your help. Thanks!
>
> Whoops, sorry I only just noticed this message. I set a reminder on my phone
> to bug me to push it tomorrow :), sorry about the delay
>

Wayne, I don't see why we couldn't give you commit permissions for drm-misc.

Alex

> >
> > > -----Original Message-----
> > > From: Lyude Paul <lyude@redhat.com>
> > > Sent: Thursday, August 24, 2023 5:00 AM
> > > To: Lin, Wayne <Wayne.Lin@amd.com>; dri-devel@lists.freedesktop.org;
> > > amd-gfx@lists.freedesktop.org
> > > Cc: jani.nikula@intel.com; ville.syrjala@linux.intel.com; imre.deak@intel.com;
> > > Wentland, Harry <Harry.Wentland@amd.com>; Zuo, Jerry
> > > <Jerry.Zuo@amd.com>
> > > Subject: Re: [Patch v2 2/3] drm/mst: Refactor the flow for payload
> > > allocation/removement
> > >
> > > Sure - you're also welcome to push the first two patches after fixing the
> > > indentation if you'd like
> > >
> > > On Wed, 2023-08-23 at 03:19 +0000, Lin, Wayne wrote:
> > > > [Public]
> > > >
> > > > Thanks, Lyude!
> > > > Should I push another version to fix the indention?
> > > >
> > > > > -----Original Message-----
> > > > > From: Lyude Paul <lyude@redhat.com>
> > > > > Sent: Friday, August 18, 2023 6:17 AM
> > > > > To: Lin, Wayne <Wayne.Lin@amd.com>; dri-devel@lists.freedesktop.org;
> > > > > amd-gfx@lists.freedesktop.org
> > > > > Cc: jani.nikula@intel.com; ville.syrjala@linux.intel.com;
> > > > > imre.deak@intel.com; Wentland, Harry <Harry.Wentland@amd.com>; Zuo,
> > > > > Jerry <Jerry.Zuo@amd.com>
> > > > > Subject: Re: [Patch v2 2/3] drm/mst: Refactor the flow for payload
> > > > > allocation/removement
> > > > >
> > > > > Two small comments:
> > > > >
> > > > > On Mon, 2023-08-07 at 10:56 +0800, Wayne Lin wrote:
> > > > > > [Why]
> > > > > > Today, the allocation/deallocation steps and status is a bit unclear.
> > > > > >
> > > > > > For instance, payload->vc_start_slot = -1 stands for "the failure
> > > > > > of updating DPCD payload ID table" and can also represent as
> > > > > > "payload is not allocated yet". These two cases should be handled
> > > > > > differently and hence better to distinguish them for better understanding.
> > > > > >
> > > > > > [How]
> > > > > > Define enumeration - ALLOCATION_LOCAL, ALLOCATION_DFP and
> > > > > > ALLOCATION_REMOTE to distinguish different allocation status.
> > > > > > Adjust the code to handle different status accordingly for better
> > > > > > understanding the sequence of payload allocation and payload
> > > > > removement.
> > > > > >
> > > > > > For payload creation, the procedure should look like this:
> > > > > > DRM part 1:
> > > > > > * step 1 - update sw mst mgr variables to add a new payload
> > > > > > * step 2 - add payload at immediate DFP DPCD payload table
> > > > > >
> > > > > > Driver:
> > > > > > * Add new payload in HW and sync up with DFP by sending ACT
> > > > > >
> > > > > > DRM Part 2:
> > > > > > * Send ALLOCATE_PAYLOAD sideband message to allocate bandwidth
> > > > > > along
> > > > > the
> > > > > >   virtual channel.
> > > > > >
> > > > > > And as for payload removement, the procedure should look like this:
> > > > > > DRM part 1:
> > > > > > * step 1 - Send ALLOCATE_PAYLOAD sideband message to release
> > > bandwidth
> > > > > >            along the virtual channel
> > > > > > * step 2 - Clear payload allocation at immediate DFP DPCD payload
> > > > > > table
> > > > > >
> > > > > > Driver:
> > > > > > * Remove the payload in HW and sync up with DFP by sending ACT
> > > > > >
> > > > > > DRM part 2:
> > > > > > * update sw mst mgr variables to remove the payload
> > > > > >
> > > > > > Note that it's fine to fail when communicate with the branch
> > > > > > device connected at immediate downstrean-facing port, but updating
> > > > > > variables of SW mst mgr and HW configuration should be conducted
> > > > > > anyway. That's because it's under commit_tail and we need to
> > > > > > complete the HW
> > > > > programming.
> > > > > >
> > > > > > Changes since v1:
> > > > > > * Remove the set but not use variable 'old_payload' in function
> > > > > >   'nv50_msto_prepare'. Catched by kernel test robot
> > > > > > <lkp@intel.com>
> > > > > >
> > > > > > Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
> > > > > > ---
> > > > > >  .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  20 ++-
> > > > > > drivers/gpu/drm/display/drm_dp_mst_topology.c | 159
> > > > > > +++++++++++------
> > > > > -
> > > > > >  drivers/gpu/drm/i915/display/intel_dp_mst.c   |  18 +-
> > > > > >  drivers/gpu/drm/nouveau/dispnv50/disp.c       |  21 +--
> > > > > >  include/drm/display/drm_dp_mst_helper.h       |  23 ++-
> > > > > >  5 files changed, 153 insertions(+), 88 deletions(-)
> > > > > >
> > > > > > diff --git
> > > > > a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > > > > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > > > > index d9a482908380..9ad509279b0a 100644
> > > > > > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > > > > +++
> > > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > > > > @@ -219,7 +219,7 @@ static void dm_helpers_construct_old_payload(
> > > > > >     /* Set correct time_slots/PBN of old payload.
> > > > > >      * other fields (delete & dsc_enabled) in
> > > > > >      * struct drm_dp_mst_atomic_payload are don't care fields
> > > > > > -    * while calling drm_dp_remove_payload()
> > > > > > +    * while calling drm_dp_remove_payload_part2()
> > > > > >      */
> > > > > >     for (i = 0; i < current_link_table.stream_count; i++) {
> > > > > >             dc_alloc =
> > > > > > @@ -262,13 +262,12 @@ bool
> > > > > > dm_helpers_dp_mst_write_payload_allocation_table(
> > > > > >
> > > > > >     mst_mgr = &aconnector->mst_root->mst_mgr;
> > > > > >     mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
> > > > > > -
> > > > > > -   /* It's OK for this to fail */
> > > > > >     new_payload = drm_atomic_get_mst_payload_state(mst_state,
> > > > > > aconnector->mst_output_port);
> > > > > >
> > > > > >     if (enable) {
> > > > > >             target_payload = new_payload;
> > > > > >
> > > > > > +           /* It's OK for this to fail */
> > > > > >             drm_dp_add_payload_part1(mst_mgr, mst_state,
> > > > > new_payload);
> > > > > >     } else {
> > > > > >             /* construct old payload by VCPI*/ @@ -276,7 +275,7 @@
> > > > > > bool
> > > > > dm_helpers_dp_mst_write_payload_allocation_table(
> > > > > >                                             new_payload, &old_payload);
> > > > > >             target_payload = &old_payload;
> > > > > >
> > > > > > -           drm_dp_remove_payload(mst_mgr, mst_state,
> > > > > &old_payload, new_payload);
> > > > > > +           drm_dp_remove_payload_part1(mst_mgr, mst_state,
> > > > > new_payload);
> > > > > >     }
> > > > > >
> > > > > >     /* mst_mgr->->payloads are VC payload notify MST branch using
> > > > > DPCD
> > > > > > or @@ -342,7 +341,7 @@ bool
> > > > > dm_helpers_dp_mst_send_payload_allocation(
> > > > > >     struct amdgpu_dm_connector *aconnector;
> > > > > >     struct drm_dp_mst_topology_state *mst_state;
> > > > > >     struct drm_dp_mst_topology_mgr *mst_mgr;
> > > > > > -   struct drm_dp_mst_atomic_payload *payload;
> > > > > > +   struct drm_dp_mst_atomic_payload *new_payload, *old_payload;
> > > > > >     enum mst_progress_status set_flag =
> > > > > MST_ALLOCATE_NEW_PAYLOAD;
> > > > > >     enum mst_progress_status clr_flag =
> > > > > MST_CLEAR_ALLOCATED_PAYLOAD;
> > > > > >     int ret = 0;
> > > > > > @@ -355,15 +354,20 @@ bool
> > > > > dm_helpers_dp_mst_send_payload_allocation(
> > > > > >     mst_mgr = &aconnector->mst_root->mst_mgr;
> > > > > >     mst_state = to_drm_dp_mst_topology_state(mst_mgr->base.state);
> > > > > >
> > > > > > -   payload = drm_atomic_get_mst_payload_state(mst_state,
> > > > > aconnector->mst_output_port);
> > > > > > +   new_payload = drm_atomic_get_mst_payload_state(mst_state,
> > > > > > +aconnector->mst_output_port);
> > > > > >
> > > > > >     if (!enable) {
> > > > > >             set_flag = MST_CLEAR_ALLOCATED_PAYLOAD;
> > > > > >             clr_flag = MST_ALLOCATE_NEW_PAYLOAD;
> > > > > >     }
> > > > > >
> > > > > > -   if (enable)
> > > > > > -           ret = drm_dp_add_payload_part2(mst_mgr, mst_state-
> > > > > > base.state, payload);
> > > > > > +   if (enable) {
> > > > > > +           ret = drm_dp_add_payload_part2(mst_mgr, mst_state-
> > > > > > base.state, new_payload);
> > > > > > +   } else {
> > > > > > +           dm_helpers_construct_old_payload(stream->link,
> > > > > > + mst_state-
> > > > > > pbn_div,
> > > > > > +                                            new_payload, old_payload);
> > > > > > +           drm_dp_remove_payload_part2(mst_mgr, mst_state,
> > > > > old_payload, new_payload);
> > > > > > +   }
> > > > > >
> > > > > >     if (ret) {
> > > > > >             amdgpu_dm_set_mst_status(&aconnector->mst_status,
> > > > > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > > > > b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > > > > index 4d80426757ab..e04f87ff755a 100644
> > > > > > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > > > > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > > > > @@ -3255,15 +3255,15 @@ int
> > > > > drm_dp_send_query_stream_enc_status(struct
> > > > > > drm_dp_mst_topology_mgr *mgr,  }
> > > > > > EXPORT_SYMBOL(drm_dp_send_query_stream_enc_status);
> > > > > >
> > > > > > -static int drm_dp_create_payload_step1(struct
> > > > > > drm_dp_mst_topology_mgr
> > > > > *mgr,
> > > > > > -                                  struct drm_dp_mst_atomic_payload
> > > > > *payload)
> > > > > > +static int drm_dp_create_payload_at_dfp(struct
> > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > > +                                   struct
> > > > > > + drm_dp_mst_atomic_payload
> > > > > *payload)
> > > > > >  {
> > > > > >     return drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload-
> > > > > > vc_start_slot,
> > > > > >                                      payload->time_slots);  }
> > > > > >
> > > > > > -static int drm_dp_create_payload_step2(struct
> > > > > > drm_dp_mst_topology_mgr
> > > > > *mgr,
> > > > > > -                                  struct drm_dp_mst_atomic_payload
> > > > > *payload)
> > > > > > +static int drm_dp_create_payload_to_remote(struct
> > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > > +                                      struct
> > > > > > + drm_dp_mst_atomic_payload
> > > > > *payload)
> > > > > >  {
> > > > > >     int ret;
> > > > > >     struct drm_dp_mst_port *port =
> > > > > > drm_dp_mst_topology_get_port_validated(mgr, payload->port); @@ -
> > > > > 3276,17 +3276,20 @@ static int drm_dp_create_payload_step2(struct
> > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > >     return ret;
> > > > > >  }
> > > > > >
> > > > > > -static int drm_dp_destroy_payload_step1(struct
> > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > > -                                   struct drm_dp_mst_topology_state
> > > > > *mst_state,
> > > > > > -                                   struct drm_dp_mst_atomic_payload
> > > > > *payload)
> > > > > > +static void drm_dp_destroy_payload_at_remote_and_dfp(struct
> > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > > +                                                struct
> > > > > drm_dp_mst_topology_state *mst_state,
> > > > > > +                                                struct
> > > > > drm_dp_mst_atomic_payload *payload)
> > > > > >  {
> > > > > >     drm_dbg_kms(mgr->dev, "\n");
> > > > > >
> > > > > >     /* it's okay for these to fail */
> > > > > > -   drm_dp_payload_send_msg(mgr, payload->port, payload->vcpi, 0);
> > > > > > -   drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload-
> > > > > > vc_start_slot, 0);
> > > > > > +   if (payload->payload_allocation_status ==
> > > > > DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE) {
> > > > > > +           drm_dp_payload_send_msg(mgr, payload->port, payload-
> > > > > > vcpi, 0);
> > > > > > +           payload->payload_allocation_status =
> > > > > DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
> > > > > > +   }
> > > > > >
> > > > > > -   return 0;
> > > > > > +   if (payload->payload_allocation_status ==
> > > > > DRM_DP_MST_PAYLOAD_ALLOCATION_DFP)
> > > > > > +           drm_dp_dpcd_write_payload(mgr, payload->vcpi,
> > > > > > +payload->vc_start_slot, 0);
> > > > > >  }
> > > > > >
> > > > > >  /**
> > > > > > @@ -3296,81 +3299,105 @@ static int
> > > > > drm_dp_destroy_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
> > > > > >   * @payload: The payload to write
> > > > > >   *
> > > > > >   * Determines the starting time slot for the given payload, and
> > > > > > programs the VCPI for this payload
> > > > > > - * into hardware. After calling this, the driver should generate
> > > > > > ACT and
> > > > > payload packets.
> > > > > > + * into the DPCD of DPRX. After calling this, the driver should
> > > > > > + generate ACT
> > > > > and payload packets.
> > > > > >   *
> > > > > > - * Returns: 0 on success, error code on failure. In the event
> > > > > > that this fails,
> > > > > > - * @payload.vc_start_slot will also be set to -1.
> > > > > > + * Returns: 0 on success, error code on failure.
> > > > > >   */
> > > > > >  int drm_dp_add_payload_part1(struct drm_dp_mst_topology_mgr
> > > *mgr,
> > > > > >                          struct drm_dp_mst_topology_state *mst_state,
> > > > > >                          struct drm_dp_mst_atomic_payload *payload)  {
> > > > > >     struct drm_dp_mst_port *port;
> > > > > > -   int ret;
> > > > > > +   int ret = 0;
> > > > > > +   bool allocate = true;
> > > > > > +
> > > > > > +   /* Update mst mgr info */
> > > > > > +   if (mgr->payload_count == 0)
> > > > > > +           mgr->next_start_slot = mst_state->start_slot;
> > > > > > +
> > > > > > +   payload->vc_start_slot = mgr->next_start_slot;
> > > > > > +
> > > > > > +   mgr->payload_count++;
> > > > > > +   mgr->next_start_slot += payload->time_slots;
> > > > > >
> > > > > > +   /* Allocate payload to immediate downstream facing port */
> > > > > >     port = drm_dp_mst_topology_get_port_validated(mgr, payload-
> > > > > > port);
> > > > > >     if (!port) {
> > > > > >             drm_dbg_kms(mgr->dev,
> > > > > > -                       "VCPI %d for port %p not in topology, not creating a
> > > > > payload\n",
> > > > > > +                       "VCPI %d for port %p not in topology, not
> > > > > > + creating a
> > > > > payload
> > > > > > +to remote\n",
> > > > > >                         payload->vcpi, payload->port);
> > > > > > -           payload->vc_start_slot = -1;
> > > > > > -           return 0;
> > > > > > +           allocate = false;
> > > > > >     }
> > > > > >
> > > > > > -   if (mgr->payload_count == 0)
> > > > > > -           mgr->next_start_slot = mst_state->start_slot;
> > > > > > -
> > > > > > -   payload->vc_start_slot = mgr->next_start_slot;
> > > > > > +   if (allocate) {
> > > > > > +           ret = drm_dp_create_payload_at_dfp(mgr, payload);
> > > > > > +           if (ret < 0)
> > > > > > +                   drm_warn(mgr->dev, "Failed to create MST
> > > > > > + payload
> > > > > for port %p: %d\n",
> > > > > > +                            payload->port, ret);
> > > > > >
> > > > > > -   ret = drm_dp_create_payload_step1(mgr, payload);
> > > > > > -   drm_dp_mst_topology_put_port(port);
> > > > > > -   if (ret < 0) {
> > > > > > -           drm_warn(mgr->dev, "Failed to create MST payload for port
> > > > > %p: %d\n",
> > > > > > -                    payload->port, ret);
> > > > > > -           payload->vc_start_slot = -1;
> > > > > > -           return ret;
> > > > > >     }
> > > > > >
> > > > > > -   mgr->payload_count++;
> > > > > > -   mgr->next_start_slot += payload->time_slots;
> > > > > > +   payload->payload_allocation_status =
> > > > > > +           (!allocate || ret < 0) ?
> > > > > DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL :
> > > > > > +
> > > > >       DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
> > > > >
> > > > > Just need to fix indenting here
> > > > >
> > > > > >
> > > > > > -   return 0;
> > > > > > +   drm_dp_mst_topology_put_port(port);
> > > > > > +
> > > > > > +   return ret;
> > > > > >  }
> > > > > >  EXPORT_SYMBOL(drm_dp_add_payload_part1);
> > > > > >
> > > > > >  /**
> > > > > > - * drm_dp_remove_payload() - Remove an MST payload
> > > > > > + * drm_dp_remove_payload_part1() - Remove an MST payload along
> > > > > > + the virtual channel
> > > > > >   * @mgr: Manager to use.
> > > > > >   * @mst_state: The MST atomic state
> > > > > > - * @old_payload: The payload with its old state
> > > > > > - * @new_payload: The payload to write
> > > > > > + * @payload: The payload to remove
> > > > > >   *
> > > > > > - * Removes a payload from an MST topology if it was successfully
> > > > > > assigned a start slot. Also updates
> > > > > > - * the starting time slots of all other payloads which would have
> > > > > > been shifted towards the start of
> > > > > > - * the VC table as a result. After calling this, the driver
> > > > > > should generate ACT
> > > > > and payload packets.
> > > > > > + * Removes a payload along the virtual channel if it was
> > > > > > + successfully
> > > > > allocated.
> > > > > > + * After calling this, the driver should set HW to generate ACT
> > > > > > + and then switch to new
> > > > > > + * payload allocation state.
> > > > > >   */
> > > > > > -void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
> > > > > > -                      struct drm_dp_mst_topology_state *mst_state,
> > > > > > -                      const struct drm_dp_mst_atomic_payload
> > > > > *old_payload,
> > > > > > -                      struct drm_dp_mst_atomic_payload *new_payload)
> > > > > > +void drm_dp_remove_payload_part1(struct
> > > drm_dp_mst_topology_mgr
> > > > > *mgr,
> > > > > > +                            struct drm_dp_mst_topology_state
> > > > > *mst_state,
> > > > > > +                            struct drm_dp_mst_atomic_payload
> > > > > *payload)
> > > > > >  {
> > > > > > -   struct drm_dp_mst_atomic_payload *pos;
> > > > > > +   /* Remove remote payload allocation */
> > > > > >     bool send_remove = false;
> > > > > >
> > > > > > -   /* We failed to make the payload, so nothing to do */
> > > > > > -   if (new_payload->vc_start_slot == -1)
> > > > > > -           return;
> > > > > > -
> > > > > >     mutex_lock(&mgr->lock);
> > > > > > -   send_remove =
> > > > > drm_dp_mst_port_downstream_of_branch(new_payload->port, mgr-
> > > > > > mst_primary);
> > > > > > +   send_remove = drm_dp_mst_port_downstream_of_branch(payload-
> > > > > > port,
> > > > > > +mgr->mst_primary);
> > > > > >     mutex_unlock(&mgr->lock);
> > > > > >
> > > > > >     if (send_remove)
> > > > > > -           drm_dp_destroy_payload_step1(mgr, mst_state,
> > > > > new_payload);
> > > > > > +           drm_dp_destroy_payload_at_remote_and_dfp(mgr,
> > > > > mst_state, payload);
> > > > > >     else
> > > > > >             drm_dbg_kms(mgr->dev, "Payload for VCPI %d not in
> > > > > topology, not sending remove\n",
> > > > > > -                       new_payload->vcpi);
> > > > > > +                       payload->vcpi);
> > > > > > +
> > > > > > +   payload->payload_allocation_status =
> > > > > > +DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL;
> > > > > > +}
> > > > > > +EXPORT_SYMBOL(drm_dp_remove_payload_part1);
> > > > > >
> > > > > > +/**
> > > > > > + * drm_dp_remove_payload_part2() - Remove an MST payload locally
> > > > > > + * @mgr: Manager to use.
> > > > > > + * @mst_state: The MST atomic state
> > > > > > + * @old_payload: The payload with its old state
> > > > > > + * @new_payload: The payload with its latest state
> > > > > > + *
> > > > > > + * Updates the starting time slots of all other payloads which
> > > > > > +would have been shifted towards
> > > > > > + * the start of the payload ID table as a result of removing a
> > > > > > +payload. Driver should call this
> > > > > > + * function whenever it removes a payload in its HW. It's
> > > > > > +independent to the result of payload
> > > > > > + * allocation/deallocation at branch devices along the virtual channel.
> > > > > > + */
> > > > > > +void drm_dp_remove_payload_part2(struct
> > > drm_dp_mst_topology_mgr
> > > > > *mgr,
> > > > > > +                            struct drm_dp_mst_topology_state
> > > > > *mst_state,
> > > > > > +                            const struct
> > > > > > + drm_dp_mst_atomic_payload
> > > > > *old_payload,
> > > > > > +                            struct drm_dp_mst_atomic_payload
> > > > > *new_payload) {
> > > > > > +   struct drm_dp_mst_atomic_payload *pos;
> > > > > > +
> > > > > > +   /* Remove local payload allocation */
> > > > > >     list_for_each_entry(pos, &mst_state->payloads, next) {
> > > > > >             if (pos != new_payload && pos->vc_start_slot >
> > > > > > new_payload-
> > > > > > vc_start_slot)
> > > > > >                     pos->vc_start_slot -= old_payload->time_slots;
> > > > > > @@ -
> > > > > 3382,9 +3409,10
> > > > > > @@ void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr
> > > > > *mgr,
> > > > > >
> > > > > >     if (new_payload->delete)
> > > > > >             drm_dp_mst_put_port_malloc(new_payload->port);
> > > > > > -}
> > > > > > -EXPORT_SYMBOL(drm_dp_remove_payload);
> > > > > >
> > > > > > +   new_payload->payload_allocation_status =
> > > > > > +DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
> > > > > > +}
> > > > > > +EXPORT_SYMBOL(drm_dp_remove_payload_part2);
> > > > > >  /**
> > > > > >   * drm_dp_add_payload_part2() - Execute payload update part 2
> > > > > >   * @mgr: Manager to use.
> > > > > > @@ -3403,17 +3431,19 @@ int drm_dp_add_payload_part2(struct
> > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > >     int ret = 0;
> > > > > >
> > > > > >     /* Skip failed payloads */
> > > > > > -   if (payload->vc_start_slot == -1) {
> > > > > > -           drm_dbg_kms(mgr->dev, "Part 1 of payload creation for %s
> > > > > failed, skipping part 2\n",
> > > > > > +   if (payload->payload_allocation_status !=
> > > > > DRM_DP_MST_PAYLOAD_ALLOCATION_DFP) {
> > > > > > +           drm_dbg_kms(state->dev, "Part 1 of payload creation
> > > > > > + for %s
> > > > > failed,
> > > > > > +skipping part 2\n",
> > > > > >                         payload->port->connector->name);
> > > > > >             return -EIO;
> > > > > >     }
> > > > > >
> > > > > > -   ret = drm_dp_create_payload_step2(mgr, payload);
> > > > > > -   if (ret < 0) {
> > > > > > +   /* Allocate payload to remote end */
> > > > > > +   ret = drm_dp_create_payload_to_remote(mgr, payload);
> > > > > > +   if (ret < 0)
> > > > > >             drm_err(mgr->dev, "Step 2 of creating MST payload for
> > > > > > %p
> > > > > failed: %d\n",
> > > > > >                     payload->port, ret);
> > > > > > -   }
> > > > > > +   else
> > > > > > +           payload->payload_allocation_status =
> > > > > > +DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE;
> > > > > >
> > > > > >     return ret;
> > > > > >  }
> > > > > > @@ -4324,6 +4354,7 @@ int drm_dp_atomic_find_time_slots(struct
> > > > > drm_atomic_state *state,
> > > > > >             drm_dp_mst_get_port_malloc(port);
> > > > > >             payload->port = port;
> > > > > >             payload->vc_start_slot = -1;
> > > > > > +           payload->payload_allocation_status =
> > > > > > +DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
> > > > > >             list_add(&payload->next, &topology_state->payloads);
> > > > > >     }
> > > > > >     payload->time_slots = req_slots; @@ -4493,7 +4524,7 @@ void
> > > > > drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state
> > > > > *state)
> > > > > >             }
> > > > > >
> > > > > >             /* Now that previous state is committed, it's safe to
> > > > > > copy over
> > > > > the start slot
> > > > > > -            * assignments
> > > > > > +            * and allocation status assignments
> > > > > >              */
> > > > > >             list_for_each_entry(old_payload,
> > > > > > &old_mst_state->payloads,
> > > > > next) {
> > > > > >                     if (old_payload->delete) @@ -4502,6 +4533,8 @@
> > > > > > void
> > > > > drm_dp_mst_atomic_wait_for_dependencies(struct drm_atomic_state
> > > > > *state)
> > > > > >                     new_payload =
> > > > > drm_atomic_get_mst_payload_state(new_mst_state,
> > > > > >
> > > > > old_payload->port);
> > > > > >                     new_payload->vc_start_slot = old_payload-
> > > > > > vc_start_slot;
> > > > > > +                   new_payload->payload_allocation_status =
> > > > > > +                                                   old_payload-
> > > > > > payload_allocation_status;
> > > > >
> > > > > And here. Besides that, I think patches 1/3 and 2/3 look great! Just
> > > > > finished testing them on nouveau:
> > > > >
> > > > > Reviewed-by: Lyude Paul <lyude@redhat.com>
> > > > >
> > > > > Patch 3/3 I gotta think about a bit more (and am curious about
> > > > > Imre's current take on it) I think
> > > > >
> > > > > >             }
> > > > > >     }
> > > > > >  }
> > > > > > @@ -4818,6 +4851,13 @@ void drm_dp_mst_dump_topology(struct
> > > > > seq_file *m,
> > > > > >     struct drm_dp_mst_atomic_payload *payload;
> > > > > >     int i, ret;
> > > > > >
> > > > > > +   static const char *const status[] = {
> > > > > > +           "None",
> > > > > > +           "Local",
> > > > > > +           "DFP",
> > > > > > +           "Remote",
> > > > > > +   };
> > > > > > +
> > > > > >     mutex_lock(&mgr->lock);
> > > > > >     if (mgr->mst_primary)
> > > > > >             drm_dp_mst_dump_mstb(m, mgr->mst_primary); @@ -
> > > > > 4834,7 +4874,7 @@
> > > > > > void drm_dp_mst_dump_topology(struct seq_file *m,
> > > > > >     seq_printf(m, "payload_mask: %x, max_payloads: %d, start_slot:
> > > > > > %u,
> > > > > pbn_div: %d\n",
> > > > > >                state->payload_mask, mgr->max_payloads, state-
> > > > > > start_slot,
> > > > > > state->pbn_div);
> > > > > >
> > > > > > -   seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc |     sink name
> > > > > > \n");
> > > > > > +   seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc | status |     sink
> > > > > name     |\n");
> > > > > >     for (i = 0; i < mgr->max_payloads; i++) {
> > > > > >             list_for_each_entry(payload, &state->payloads, next) {
> > > > > >                     char name[14]; @@ -4843,7 +4883,7 @@ void
> > > > > > drm_dp_mst_dump_topology(struct
> > > > > seq_file *m,
> > > > > >                             continue;
> > > > > >
> > > > > >                     fetch_monitor_name(mgr, payload->port, name,
> > > > > sizeof(name));
> > > > > > -                   seq_printf(m, " %5d %6d %6d %02d - %02d %5d %5s
> > > > > %19s\n",
> > > > > > +                   seq_printf(m, " %5d %6d %6d %02d - %02d %5d
> > > > > > + %5s
> > > > > %8s %19s\n",
> > > > > >                                i,
> > > > > >                                payload->port->port_num,
> > > > > >                                payload->vcpi, @@ -4851,6 +4891,7
> > > > > > @@ void drm_dp_mst_dump_topology(struct
> > > > > seq_file *m,
> > > > > >                                payload->vc_start_slot + payload-
> > > > > > time_slots - 1,
> > > > > >                                payload->pbn,
> > > > > >                                payload->dsc_enabled ? "Y" : "N",
> > > > > > +
> > > > > > + status[payload->payload_allocation_status],
> > > > > >                                (*name != 0) ? name : "Unknown");
> > > > > >             }
> > > > > >     }
> > > > > > diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > > > > b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > > > > index e3f176a093d2..5f73cdabe7a1 100644
> > > > > > --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > > > > +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > > > > @@ -557,12 +557,8 @@ static void intel_mst_disable_dp(struct
> > > > > intel_atomic_state *state,
> > > > > >     struct intel_dp *intel_dp = &dig_port->dp;
> > > > > >     struct intel_connector *connector =
> > > > > >             to_intel_connector(old_conn_state->connector);
> > > > > > -   struct drm_dp_mst_topology_state *old_mst_state =
> > > > > > -           drm_atomic_get_old_mst_topology_state(&state->base,
> > > > > &intel_dp->mst_mgr);
> > > > > >     struct drm_dp_mst_topology_state *new_mst_state =
> > > > > >             drm_atomic_get_new_mst_topology_state(&state->base,
> > > > > &intel_dp->mst_mgr);
> > > > > > -   const struct drm_dp_mst_atomic_payload *old_payload =
> > > > > > -           drm_atomic_get_mst_payload_state(old_mst_state,
> > > > > connector->port);
> > > > > >     struct drm_dp_mst_atomic_payload *new_payload =
> > > > > >             drm_atomic_get_mst_payload_state(new_mst_state,
> > > > > connector->port);
> > > > > >     struct drm_i915_private *i915 = to_i915(connector->base.dev);
> > > > > > @@
> > > > > > -572,8 +568,7 @@ static void intel_mst_disable_dp(struct
> > > > > > intel_atomic_state *state,
> > > > > >
> > > > > >     intel_hdcp_disable(intel_mst->connector);
> > > > > >
> > > > > > -   drm_dp_remove_payload(&intel_dp->mst_mgr, new_mst_state,
> > > > > > -                         old_payload, new_payload);
> > > > > > +   drm_dp_remove_payload_part1(&intel_dp->mst_mgr,
> > > > > new_mst_state,
> > > > > > +new_payload);
> > > > > >
> > > > > >     intel_audio_codec_disable(encoder, old_crtc_state,
> > > > > > old_conn_state); } @@ -588,6 +583,14 @@ static void
> > > > > > intel_mst_post_disable_dp(struct intel_atomic_state *state,
> > > > > >     struct intel_dp *intel_dp = &dig_port->dp;
> > > > > >     struct intel_connector *connector =
> > > > > >             to_intel_connector(old_conn_state->connector);
> > > > > > +   struct drm_dp_mst_topology_state *old_mst_state =
> > > > > > +           drm_atomic_get_old_mst_topology_state(&state->base,
> > > > > &intel_dp->mst_mgr);
> > > > > > +   struct drm_dp_mst_topology_state *new_mst_state =
> > > > > > +           drm_atomic_get_new_mst_topology_state(&state->base,
> > > > > &intel_dp->mst_mgr);
> > > > > > +   const struct drm_dp_mst_atomic_payload *old_payload =
> > > > > > +           drm_atomic_get_mst_payload_state(old_mst_state,
> > > > > connector->port);
> > > > > > +   struct drm_dp_mst_atomic_payload *new_payload =
> > > > > > +           drm_atomic_get_mst_payload_state(new_mst_state,
> > > > > connector->port);
> > > > > >     struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
> > > > > >     bool last_mst_stream;
> > > > > >
> > > > > > @@ -608,6 +611,9 @@ static void intel_mst_post_disable_dp(struct
> > > > > > intel_atomic_state *state,
> > > > > >
> > > > > >     wait_for_act_sent(encoder, old_crtc_state);
> > > > > >
> > > > > > +   drm_dp_remove_payload_part2(&intel_dp->mst_mgr,
> > > > > new_mst_state,
> > > > > > +                               old_payload, new_payload);
> > > > > > +
> > > > > >     intel_ddi_disable_transcoder_func(old_crtc_state);
> > > > > >
> > > > > >     if (DISPLAY_VER(dev_priv) >= 9) diff --git
> > > > > > a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > > > > b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > > > > index 4e7c9c353c51..bba01fa0780c 100644
> > > > > > --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > > > > +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > > > > @@ -882,21 +882,26 @@ struct nouveau_encoder
> > > > > > *nv50_real_outp(struct drm_encoder *encoder)
> > > > > >
> > > > > >  static void
> > > > > >  nv50_msto_cleanup(struct drm_atomic_state *state,
> > > > > > -             struct drm_dp_mst_topology_state *mst_state,
> > > > > > +             struct drm_dp_mst_topology_state *new_mst_state,
> > > > > >               struct drm_dp_mst_topology_mgr *mgr,
> > > > > >               struct nv50_msto *msto)  {
> > > > > >     struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
> > > > > > -   struct drm_dp_mst_atomic_payload *payload =
> > > > > > -           drm_atomic_get_mst_payload_state(mst_state, msto->mstc-
> > > > > > port);
> > > > > > +   struct drm_dp_mst_atomic_payload *new_payload =
> > > > > > +           drm_atomic_get_mst_payload_state(new_mst_state, msto-
> > > > > > mstc->port);
> > > > > > +   struct drm_dp_mst_topology_state *old_mst_state =
> > > > > > +           drm_atomic_get_old_mst_topology_state(state, mgr);
> > > > > > +   const struct drm_dp_mst_atomic_payload *old_payload =
> > > > > > +           drm_atomic_get_mst_payload_state(old_mst_state, msto-
> > > > > > mstc->port);
> > > > > >
> > > > > >     NV_ATOMIC(drm, "%s: msto cleanup\n", msto->encoder.name);
> > > > > >
> > > > > >     if (msto->disabled) {
> > > > > >             msto->mstc = NULL;
> > > > > >             msto->disabled = false;
> > > > > > +           drm_dp_remove_payload_part2(mgr, new_mst_state,
> > > > > old_payload,
> > > > > > +new_payload);
> > > > > >     } else if (msto->enabled) {
> > > > > > -           drm_dp_add_payload_part2(mgr, state, payload);
> > > > > > +           drm_dp_add_payload_part2(mgr, state, new_payload);
> > > > > >             msto->enabled = false;
> > > > > >     }
> > > > > >  }
> > > > > > @@ -910,19 +915,15 @@ nv50_msto_prepare(struct drm_atomic_state
> > > > > *state,
> > > > > >     struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
> > > > > >     struct nv50_mstc *mstc = msto->mstc;
> > > > > >     struct nv50_mstm *mstm = mstc->mstm;
> > > > > > -   struct drm_dp_mst_topology_state *old_mst_state;
> > > > > > -   struct drm_dp_mst_atomic_payload *payload, *old_payload;
> > > > > > +   struct drm_dp_mst_atomic_payload *payload;
> > > > > >
> > > > > >     NV_ATOMIC(drm, "%s: msto prepare\n", msto->encoder.name);
> > > > > >
> > > > > > -   old_mst_state = drm_atomic_get_old_mst_topology_state(state,
> > > > > mgr);
> > > > > > -
> > > > > >     payload = drm_atomic_get_mst_payload_state(mst_state, mstc-
> > > > > > port);
> > > > > > -   old_payload = drm_atomic_get_mst_payload_state(old_mst_state,
> > > > > mstc->port);
> > > > > >
> > > > > >     // TODO: Figure out if we want to do a better job of handling
> > > > > > VCPI
> > > > > allocation failures here?
> > > > > >     if (msto->disabled) {
> > > > > > -           drm_dp_remove_payload(mgr, mst_state, old_payload,
> > > > > payload);
> > > > > > +           drm_dp_remove_payload_part1(mgr, mst_state, payload);
> > > > > >
> > > > > >             nvif_outp_dp_mst_vcpi(&mstm->outp->outp, msto->head-
> > > > > > base.index, 0, 0, 0, 0);
> > > > > >     } else {
> > > > > > diff --git a/include/drm/display/drm_dp_mst_helper.h
> > > > > > b/include/drm/display/drm_dp_mst_helper.h
> > > > > > index ed5c9660563c..4429d3b1745b 100644
> > > > > > --- a/include/drm/display/drm_dp_mst_helper.h
> > > > > > +++ b/include/drm/display/drm_dp_mst_helper.h
> > > > > > @@ -46,6 +46,13 @@ struct drm_dp_mst_topology_ref_history {  };
> > > > > > #endif /*
> > > IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) */
> > > > > >
> > > > > > +enum drm_dp_mst_payload_allocation {
> > > > > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_NONE,
> > > > > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL,
> > > > > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_DFP,
> > > > > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE,
> > > > > > +};
> > > > > > +
> > > > > >  struct drm_dp_mst_branch;
> > > > > >
> > > > > >  /**
> > > > > > @@ -537,7 +544,7 @@ struct drm_dp_mst_atomic_payload {
> > > > > >      *   drm_dp_mst_atomic_wait_for_dependencies() has been called,
> > > > > which will ensure the
> > > > > >      *   previous MST states payload start slots have been copied over to
> > > > > the new state. Note
> > > > > >      *   that a new start slot won't be assigned/removed from this payload
> > > > > until
> > > > > > -    *   drm_dp_add_payload_part1()/drm_dp_remove_payload() have
> > > > > been called.
> > > > > > +    *   drm_dp_add_payload_part1()/drm_dp_remove_payload_part2()
> > > > > have been called.
> > > > > >      * * Acquire the MST modesetting lock, and then wait for any
> > > > > > pending
> > > > > MST-related commits to
> > > > > >      *   get committed to hardware by calling drm_crtc_commit_wait() on
> > > > > each of the
> > > > > >      *   &drm_crtc_commit structs in
> > > > > &drm_dp_mst_topology_state.commit_deps.
> > > > > > @@ -564,6 +571,9 @@ struct drm_dp_mst_atomic_payload {
> > > > > >     /** @dsc_enabled: Whether or not this payload has DSC enabled */
> > > > > >     bool dsc_enabled : 1;
> > > > > >
> > > > > > +   /** @payload_allocation_status: The allocation status of this
> > > > > > + payload
> > > > > */
> > > > > > +   enum drm_dp_mst_payload_allocation payload_allocation_status;
> > > > > > +
> > > > > >     /** @next: The list node for this payload */
> > > > > >     struct list_head next;
> > > > > >  };
> > > > > > @@ -842,10 +852,13 @@ int drm_dp_add_payload_part1(struct
> > > > > > drm_dp_mst_topology_mgr *mgr,  int
> > > drm_dp_add_payload_part2(struct
> > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > >                          struct drm_atomic_state *state,
> > > > > >                          struct drm_dp_mst_atomic_payload
> > > > > > *payload); -
> > > > > void
> > > > > > drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
> > > > > > -                      struct drm_dp_mst_topology_state *mst_state,
> > > > > > -                      const struct drm_dp_mst_atomic_payload
> > > > > *old_payload,
> > > > > > -                      struct drm_dp_mst_atomic_payload
> > > > > *new_payload);
> > > > > > +void drm_dp_remove_payload_part1(struct
> > > drm_dp_mst_topology_mgr
> > > > > *mgr,
> > > > > > +                            struct drm_dp_mst_topology_state
> > > > > *mst_state,
> > > > > > +                            struct drm_dp_mst_atomic_payload
> > > > > *payload); void
> > > > > > +drm_dp_remove_payload_part2(struct drm_dp_mst_topology_mgr
> > > *mgr,
> > > > > > +                            struct drm_dp_mst_topology_state
> > > > > *mst_state,
> > > > > > +                            const struct
> > > > > > + drm_dp_mst_atomic_payload
> > > > > *old_payload,
> > > > > > +                            struct drm_dp_mst_atomic_payload
> > > > > *new_payload);
> > > > > >
> > > > > >  int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr);
> > > > > >
> > > > >
> > > > > --
> > > > > Cheers,
> > > > >  Lyude Paul (she/her)
> > > > >  Software Engineer at Red Hat
> > > > --
> > > > Regards,
> > > > Wayne
> > >
> > > --
> > > Cheers,
> > >  Lyude Paul (she/her)
> > >  Software Engineer at Red Hat
> > --
> > Regards,
> > Wayne
> >
>
> --
> Cheers,
>  Lyude Paul (she/her)
>  Software Engineer at Red Hat
>

RE: [Patch v2 2/3] drm/mst: Refactor the flow for payload allocation/removement

[Lin, Wayne]

[Public]

Thank you Lyude and Alex!

Regards,
Wayne
> -----Original Message-----
> From: Alex Deucher <alexdeucher@gmail.com>
> Sent: Saturday, September 2, 2023 3:38 AM
> To: Lyude Paul <lyude@redhat.com>
> Cc: Lin, Wayne <Wayne.Lin@amd.com>; dri-devel@lists.freedesktop.org;
> amd-gfx@lists.freedesktop.org; jani.nikula@intel.com; imre.deak@intel.com;
> Wentland, Harry <Harry.Wentland@amd.com>; Zuo, Jerry
> <Jerry.Zuo@amd.com>; ville.syrjala@linux.intel.com
> Subject: Re: [Patch v2 2/3] drm/mst: Refactor the flow for payload
> allocation/removement
>
> On Thu, Aug 31, 2023 at 6:45 PM Lyude Paul <lyude@redhat.com> wrote:
> >
> > On Thu, 2023-08-24 at 04:12 +0000, Lin, Wayne wrote:
> > > [Public]
> > >
> > > Hi Lyude,
> > >
> > > I'm afraid that I don't have the permissions to push and would like
> > > to have your help. Thanks!
> >
> > Whoops, sorry I only just noticed this message. I set a reminder on my
> > phone to bug me to push it tomorrow :), sorry about the delay
> >
>
> Wayne, I don't see why we couldn't give you commit permissions for drm-
> misc.
>
> Alex
>
> > >
> > > > -----Original Message-----
> > > > From: Lyude Paul <lyude@redhat.com>
> > > > Sent: Thursday, August 24, 2023 5:00 AM
> > > > To: Lin, Wayne <Wayne.Lin@amd.com>;
> > > > dri-devel@lists.freedesktop.org; amd-gfx@lists.freedesktop.org
> > > > Cc: jani.nikula@intel.com; ville.syrjala@linux.intel.com;
> > > > imre.deak@intel.com; Wentland, Harry <Harry.Wentland@amd.com>;
> > > > Zuo, Jerry <Jerry.Zuo@amd.com>
> > > > Subject: Re: [Patch v2 2/3] drm/mst: Refactor the flow for payload
> > > > allocation/removement
> > > >
> > > > Sure - you're also welcome to push the first two patches after
> > > > fixing the indentation if you'd like
> > > >
> > > > On Wed, 2023-08-23 at 03:19 +0000, Lin, Wayne wrote:
> > > > > [Public]
> > > > >
> > > > > Thanks, Lyude!
> > > > > Should I push another version to fix the indention?
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: Lyude Paul <lyude@redhat.com>
> > > > > > Sent: Friday, August 18, 2023 6:17 AM
> > > > > > To: Lin, Wayne <Wayne.Lin@amd.com>;
> > > > > > dri-devel@lists.freedesktop.org; amd-gfx@lists.freedesktop.org
> > > > > > Cc: jani.nikula@intel.com; ville.syrjala@linux.intel.com;
> > > > > > imre.deak@intel.com; Wentland, Harry <Harry.Wentland@amd.com>;
> > > > > > Zuo, Jerry <Jerry.Zuo@amd.com>
> > > > > > Subject: Re: [Patch v2 2/3] drm/mst: Refactor the flow for
> > > > > > payload allocation/removement
> > > > > >
> > > > > > Two small comments:
> > > > > >
> > > > > > On Mon, 2023-08-07 at 10:56 +0800, Wayne Lin wrote:
> > > > > > > [Why]
> > > > > > > Today, the allocation/deallocation steps and status is a bit unclear.
> > > > > > >
> > > > > > > For instance, payload->vc_start_slot = -1 stands for "the
> > > > > > > failure of updating DPCD payload ID table" and can also
> > > > > > > represent as "payload is not allocated yet". These two cases
> > > > > > > should be handled differently and hence better to distinguish them
> for better understanding.
> > > > > > >
> > > > > > > [How]
> > > > > > > Define enumeration - ALLOCATION_LOCAL, ALLOCATION_DFP and
> > > > > > > ALLOCATION_REMOTE to distinguish different allocation status.
> > > > > > > Adjust the code to handle different status accordingly for
> > > > > > > better understanding the sequence of payload allocation and
> > > > > > > payload
> > > > > > removement.
> > > > > > >
> > > > > > > For payload creation, the procedure should look like this:
> > > > > > > DRM part 1:
> > > > > > > * step 1 - update sw mst mgr variables to add a new payload
> > > > > > > * step 2 - add payload at immediate DFP DPCD payload table
> > > > > > >
> > > > > > > Driver:
> > > > > > > * Add new payload in HW and sync up with DFP by sending ACT
> > > > > > >
> > > > > > > DRM Part 2:
> > > > > > > * Send ALLOCATE_PAYLOAD sideband message to allocate
> > > > > > > bandwidth along
> > > > > > the
> > > > > > >   virtual channel.
> > > > > > >
> > > > > > > And as for payload removement, the procedure should look like this:
> > > > > > > DRM part 1:
> > > > > > > * step 1 - Send ALLOCATE_PAYLOAD sideband message to release
> > > > bandwidth
> > > > > > >            along the virtual channel
> > > > > > > * step 2 - Clear payload allocation at immediate DFP DPCD
> > > > > > > payload table
> > > > > > >
> > > > > > > Driver:
> > > > > > > * Remove the payload in HW and sync up with DFP by sending
> > > > > > > ACT
> > > > > > >
> > > > > > > DRM part 2:
> > > > > > > * update sw mst mgr variables to remove the payload
> > > > > > >
> > > > > > > Note that it's fine to fail when communicate with the branch
> > > > > > > device connected at immediate downstrean-facing port, but
> > > > > > > updating variables of SW mst mgr and HW configuration should
> > > > > > > be conducted anyway. That's because it's under commit_tail
> > > > > > > and we need to complete the HW
> > > > > > programming.
> > > > > > >
> > > > > > > Changes since v1:
> > > > > > > * Remove the set but not use variable 'old_payload' in function
> > > > > > >   'nv50_msto_prepare'. Catched by kernel test robot
> > > > > > > <lkp@intel.com>
> > > > > > >
> > > > > > > Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
> > > > > > > ---
> > > > > > >  .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  20 ++-
> > > > > > > drivers/gpu/drm/display/drm_dp_mst_topology.c | 159
> > > > > > > +++++++++++------
> > > > > > -
> > > > > > >  drivers/gpu/drm/i915/display/intel_dp_mst.c   |  18 +-
> > > > > > >  drivers/gpu/drm/nouveau/dispnv50/disp.c       |  21 +--
> > > > > > >  include/drm/display/drm_dp_mst_helper.h       |  23 ++-
> > > > > > >  5 files changed, 153 insertions(+), 88 deletions(-)
> > > > > > >
> > > > > > > diff --git
> > > > > >
> a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > > > > >
> b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > > > > > index d9a482908380..9ad509279b0a 100644
> > > > > > > ---
> > > > > > >
> a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > > > > > +++
> > > > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > > > > > @@ -219,7 +219,7 @@ static void
> dm_helpers_construct_old_payload(
> > > > > > >     /* Set correct time_slots/PBN of old payload.
> > > > > > >      * other fields (delete & dsc_enabled) in
> > > > > > >      * struct drm_dp_mst_atomic_payload are don't care fields
> > > > > > > -    * while calling drm_dp_remove_payload()
> > > > > > > +    * while calling drm_dp_remove_payload_part2()
> > > > > > >      */
> > > > > > >     for (i = 0; i < current_link_table.stream_count; i++) {
> > > > > > >             dc_alloc =
> > > > > > > @@ -262,13 +262,12 @@ bool
> > > > > > > dm_helpers_dp_mst_write_payload_allocation_table(
> > > > > > >
> > > > > > >     mst_mgr = &aconnector->mst_root->mst_mgr;
> > > > > > >     mst_state =
> > > > > > > to_drm_dp_mst_topology_state(mst_mgr->base.state);
> > > > > > > -
> > > > > > > -   /* It's OK for this to fail */
> > > > > > >     new_payload =
> > > > > > > drm_atomic_get_mst_payload_state(mst_state,
> > > > > > > aconnector->mst_output_port);
> > > > > > >
> > > > > > >     if (enable) {
> > > > > > >             target_payload = new_payload;
> > > > > > >
> > > > > > > +           /* It's OK for this to fail */
> > > > > > >             drm_dp_add_payload_part1(mst_mgr, mst_state,
> > > > > > new_payload);
> > > > > > >     } else {
> > > > > > >             /* construct old payload by VCPI*/ @@ -276,7
> > > > > > > +275,7 @@ bool
> > > > > > dm_helpers_dp_mst_write_payload_allocation_table(
> > > > > > >                                             new_payload, &old_payload);
> > > > > > >             target_payload = &old_payload;
> > > > > > >
> > > > > > > -           drm_dp_remove_payload(mst_mgr, mst_state,
> > > > > > &old_payload, new_payload);
> > > > > > > +           drm_dp_remove_payload_part1(mst_mgr, mst_state,
> > > > > > new_payload);
> > > > > > >     }
> > > > > > >
> > > > > > >     /* mst_mgr->->payloads are VC payload notify MST branch
> > > > > > > using
> > > > > > DPCD
> > > > > > > or @@ -342,7 +341,7 @@ bool
> > > > > > dm_helpers_dp_mst_send_payload_allocation(
> > > > > > >     struct amdgpu_dm_connector *aconnector;
> > > > > > >     struct drm_dp_mst_topology_state *mst_state;
> > > > > > >     struct drm_dp_mst_topology_mgr *mst_mgr;
> > > > > > > -   struct drm_dp_mst_atomic_payload *payload;
> > > > > > > +   struct drm_dp_mst_atomic_payload *new_payload,
> > > > > > > + *old_payload;
> > > > > > >     enum mst_progress_status set_flag =
> > > > > > MST_ALLOCATE_NEW_PAYLOAD;
> > > > > > >     enum mst_progress_status clr_flag =
> > > > > > MST_CLEAR_ALLOCATED_PAYLOAD;
> > > > > > >     int ret = 0;
> > > > > > > @@ -355,15 +354,20 @@ bool
> > > > > > dm_helpers_dp_mst_send_payload_allocation(
> > > > > > >     mst_mgr = &aconnector->mst_root->mst_mgr;
> > > > > > >     mst_state =
> > > > > > > to_drm_dp_mst_topology_state(mst_mgr->base.state);
> > > > > > >
> > > > > > > -   payload = drm_atomic_get_mst_payload_state(mst_state,
> > > > > > aconnector->mst_output_port);
> > > > > > > +   new_payload =
> > > > > > > + drm_atomic_get_mst_payload_state(mst_state,
> > > > > > > +aconnector->mst_output_port);
> > > > > > >
> > > > > > >     if (!enable) {
> > > > > > >             set_flag = MST_CLEAR_ALLOCATED_PAYLOAD;
> > > > > > >             clr_flag = MST_ALLOCATE_NEW_PAYLOAD;
> > > > > > >     }
> > > > > > >
> > > > > > > -   if (enable)
> > > > > > > -           ret = drm_dp_add_payload_part2(mst_mgr, mst_state-
> > > > > > > base.state, payload);
> > > > > > > +   if (enable) {
> > > > > > > +           ret = drm_dp_add_payload_part2(mst_mgr,
> > > > > > > + mst_state-
> > > > > > > base.state, new_payload);
> > > > > > > +   } else {
> > > > > > > +           dm_helpers_construct_old_payload(stream->link,
> > > > > > > + mst_state-
> > > > > > > pbn_div,
> > > > > > > +                                            new_payload, old_payload);
> > > > > > > +           drm_dp_remove_payload_part2(mst_mgr, mst_state,
> > > > > > old_payload, new_payload);
> > > > > > > +   }
> > > > > > >
> > > > > > >     if (ret) {
> > > > > > >
> > > > > > > amdgpu_dm_set_mst_status(&aconnector->mst_status,
> > > > > > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > > > > > b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > > > > > index 4d80426757ab..e04f87ff755a 100644
> > > > > > > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > > > > > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > > > > > @@ -3255,15 +3255,15 @@ int
> > > > > > drm_dp_send_query_stream_enc_status(struct
> > > > > > > drm_dp_mst_topology_mgr *mgr,  }
> > > > > > > EXPORT_SYMBOL(drm_dp_send_query_stream_enc_status);
> > > > > > >
> > > > > > > -static int drm_dp_create_payload_step1(struct
> > > > > > > drm_dp_mst_topology_mgr
> > > > > > *mgr,
> > > > > > > -                                  struct drm_dp_mst_atomic_payload
> > > > > > *payload)
> > > > > > > +static int drm_dp_create_payload_at_dfp(struct
> > > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > > > +                                   struct
> > > > > > > + drm_dp_mst_atomic_payload
> > > > > > *payload)
> > > > > > >  {
> > > > > > >     return drm_dp_dpcd_write_payload(mgr, payload->vcpi,
> > > > > > > payload- vc_start_slot,
> > > > > > >                                      payload->time_slots);
> > > > > > > }
> > > > > > >
> > > > > > > -static int drm_dp_create_payload_step2(struct
> > > > > > > drm_dp_mst_topology_mgr
> > > > > > *mgr,
> > > > > > > -                                  struct drm_dp_mst_atomic_payload
> > > > > > *payload)
> > > > > > > +static int drm_dp_create_payload_to_remote(struct
> > > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > > > +                                      struct
> > > > > > > + drm_dp_mst_atomic_payload
> > > > > > *payload)
> > > > > > >  {
> > > > > > >     int ret;
> > > > > > >     struct drm_dp_mst_port *port =
> > > > > > > drm_dp_mst_topology_get_port_validated(mgr, payload->port);
> > > > > > > @@ -
> > > > > > 3276,17 +3276,20 @@ static int
> > > > > > drm_dp_create_payload_step2(struct
> > > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > > >     return ret;
> > > > > > >  }
> > > > > > >
> > > > > > > -static int drm_dp_destroy_payload_step1(struct
> > > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > > > -                                   struct drm_dp_mst_topology_state
> > > > > > *mst_state,
> > > > > > > -                                   struct drm_dp_mst_atomic_payload
> > > > > > *payload)
> > > > > > > +static void drm_dp_destroy_payload_at_remote_and_dfp(struct
> > > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > > > +                                                struct
> > > > > > drm_dp_mst_topology_state *mst_state,
> > > > > > > +                                                struct
> > > > > > drm_dp_mst_atomic_payload *payload)
> > > > > > >  {
> > > > > > >     drm_dbg_kms(mgr->dev, "\n");
> > > > > > >
> > > > > > >     /* it's okay for these to fail */
> > > > > > > -   drm_dp_payload_send_msg(mgr, payload->port, payload->vcpi,
> 0);
> > > > > > > -   drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload-
> > > > > > > vc_start_slot, 0);
> > > > > > > +   if (payload->payload_allocation_status ==
> > > > > > DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE) {
> > > > > > > +           drm_dp_payload_send_msg(mgr, payload->port,
> > > > > > > + payload-
> > > > > > > vcpi, 0);
> > > > > > > +           payload->payload_allocation_status =
> > > > > > DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
> > > > > > > +   }
> > > > > > >
> > > > > > > -   return 0;
> > > > > > > +   if (payload->payload_allocation_status ==
> > > > > > DRM_DP_MST_PAYLOAD_ALLOCATION_DFP)
> > > > > > > +           drm_dp_dpcd_write_payload(mgr, payload->vcpi,
> > > > > > > +payload->vc_start_slot, 0);
> > > > > > >  }
> > > > > > >
> > > > > > >  /**
> > > > > > > @@ -3296,81 +3299,105 @@ static int
> > > > > > drm_dp_destroy_payload_step1(struct drm_dp_mst_topology_mgr
> > > > > > *mgr,
> > > > > > >   * @payload: The payload to write
> > > > > > >   *
> > > > > > >   * Determines the starting time slot for the given payload,
> > > > > > > and programs the VCPI for this payload
> > > > > > > - * into hardware. After calling this, the driver should
> > > > > > > generate ACT and
> > > > > > payload packets.
> > > > > > > + * into the DPCD of DPRX. After calling this, the driver
> > > > > > > + should generate ACT
> > > > > > and payload packets.
> > > > > > >   *
> > > > > > > - * Returns: 0 on success, error code on failure. In the
> > > > > > > event that this fails,
> > > > > > > - * @payload.vc_start_slot will also be set to -1.
> > > > > > > + * Returns: 0 on success, error code on failure.
> > > > > > >   */
> > > > > > >  int drm_dp_add_payload_part1(struct drm_dp_mst_topology_mgr
> > > > *mgr,
> > > > > > >                          struct drm_dp_mst_topology_state *mst_state,
> > > > > > >                          struct drm_dp_mst_atomic_payload *payload)  {
> > > > > > >     struct drm_dp_mst_port *port;
> > > > > > > -   int ret;
> > > > > > > +   int ret = 0;
> > > > > > > +   bool allocate = true;
> > > > > > > +
> > > > > > > +   /* Update mst mgr info */
> > > > > > > +   if (mgr->payload_count == 0)
> > > > > > > +           mgr->next_start_slot = mst_state->start_slot;
> > > > > > > +
> > > > > > > +   payload->vc_start_slot = mgr->next_start_slot;
> > > > > > > +
> > > > > > > +   mgr->payload_count++;
> > > > > > > +   mgr->next_start_slot += payload->time_slots;
> > > > > > >
> > > > > > > +   /* Allocate payload to immediate downstream facing port
> > > > > > > + */
> > > > > > >     port = drm_dp_mst_topology_get_port_validated(mgr,
> > > > > > > payload- port);
> > > > > > >     if (!port) {
> > > > > > >             drm_dbg_kms(mgr->dev,
> > > > > > > -                       "VCPI %d for port %p not in topology, not creating a
> > > > > > payload\n",
> > > > > > > +                       "VCPI %d for port %p not in
> > > > > > > + topology, not creating a
> > > > > > payload
> > > > > > > +to remote\n",
> > > > > > >                         payload->vcpi, payload->port);
> > > > > > > -           payload->vc_start_slot = -1;
> > > > > > > -           return 0;
> > > > > > > +           allocate = false;
> > > > > > >     }
> > > > > > >
> > > > > > > -   if (mgr->payload_count == 0)
> > > > > > > -           mgr->next_start_slot = mst_state->start_slot;
> > > > > > > -
> > > > > > > -   payload->vc_start_slot = mgr->next_start_slot;
> > > > > > > +   if (allocate) {
> > > > > > > +           ret = drm_dp_create_payload_at_dfp(mgr, payload);
> > > > > > > +           if (ret < 0)
> > > > > > > +                   drm_warn(mgr->dev, "Failed to create MST
> > > > > > > + payload
> > > > > > for port %p: %d\n",
> > > > > > > +                            payload->port, ret);
> > > > > > >
> > > > > > > -   ret = drm_dp_create_payload_step1(mgr, payload);
> > > > > > > -   drm_dp_mst_topology_put_port(port);
> > > > > > > -   if (ret < 0) {
> > > > > > > -           drm_warn(mgr->dev, "Failed to create MST payload for port
> > > > > > %p: %d\n",
> > > > > > > -                    payload->port, ret);
> > > > > > > -           payload->vc_start_slot = -1;
> > > > > > > -           return ret;
> > > > > > >     }
> > > > > > >
> > > > > > > -   mgr->payload_count++;
> > > > > > > -   mgr->next_start_slot += payload->time_slots;
> > > > > > > +   payload->payload_allocation_status =
> > > > > > > +           (!allocate || ret < 0) ?
> > > > > > DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL :
> > > > > > > +
> > > > > >       DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
> > > > > >
> > > > > > Just need to fix indenting here
> > > > > >
> > > > > > >
> > > > > > > -   return 0;
> > > > > > > +   drm_dp_mst_topology_put_port(port);
> > > > > > > +
> > > > > > > +   return ret;
> > > > > > >  }
> > > > > > >  EXPORT_SYMBOL(drm_dp_add_payload_part1);
> > > > > > >
> > > > > > >  /**
> > > > > > > - * drm_dp_remove_payload() - Remove an MST payload
> > > > > > > + * drm_dp_remove_payload_part1() - Remove an MST payload
> > > > > > > + along the virtual channel
> > > > > > >   * @mgr: Manager to use.
> > > > > > >   * @mst_state: The MST atomic state
> > > > > > > - * @old_payload: The payload with its old state
> > > > > > > - * @new_payload: The payload to write
> > > > > > > + * @payload: The payload to remove
> > > > > > >   *
> > > > > > > - * Removes a payload from an MST topology if it was
> > > > > > > successfully assigned a start slot. Also updates
> > > > > > > - * the starting time slots of all other payloads which
> > > > > > > would have been shifted towards the start of
> > > > > > > - * the VC table as a result. After calling this, the driver
> > > > > > > should generate ACT
> > > > > > and payload packets.
> > > > > > > + * Removes a payload along the virtual channel if it was
> > > > > > > + successfully
> > > > > > allocated.
> > > > > > > + * After calling this, the driver should set HW to generate
> > > > > > > + ACT and then switch to new
> > > > > > > + * payload allocation state.
> > > > > > >   */
> > > > > > > -void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr
> *mgr,
> > > > > > > -                      struct drm_dp_mst_topology_state *mst_state,
> > > > > > > -                      const struct drm_dp_mst_atomic_payload
> > > > > > *old_payload,
> > > > > > > -                      struct drm_dp_mst_atomic_payload *new_payload)
> > > > > > > +void drm_dp_remove_payload_part1(struct
> > > > drm_dp_mst_topology_mgr
> > > > > > *mgr,
> > > > > > > +                            struct
> > > > > > > + drm_dp_mst_topology_state
> > > > > > *mst_state,
> > > > > > > +                            struct
> > > > > > > + drm_dp_mst_atomic_payload
> > > > > > *payload)
> > > > > > >  {
> > > > > > > -   struct drm_dp_mst_atomic_payload *pos;
> > > > > > > +   /* Remove remote payload allocation */
> > > > > > >     bool send_remove = false;
> > > > > > >
> > > > > > > -   /* We failed to make the payload, so nothing to do */
> > > > > > > -   if (new_payload->vc_start_slot == -1)
> > > > > > > -           return;
> > > > > > > -
> > > > > > >     mutex_lock(&mgr->lock);
> > > > > > > -   send_remove =
> > > > > > drm_dp_mst_port_downstream_of_branch(new_payload->port,
> mgr-
> > > > > > > mst_primary);
> > > > > > > +   send_remove =
> > > > > > > + drm_dp_mst_port_downstream_of_branch(payload-
> > > > > > > port,
> > > > > > > +mgr->mst_primary);
> > > > > > >     mutex_unlock(&mgr->lock);
> > > > > > >
> > > > > > >     if (send_remove)
> > > > > > > -           drm_dp_destroy_payload_step1(mgr, mst_state,
> > > > > > new_payload);
> > > > > > > +           drm_dp_destroy_payload_at_remote_and_dfp(mgr,
> > > > > > mst_state, payload);
> > > > > > >     else
> > > > > > >             drm_dbg_kms(mgr->dev, "Payload for VCPI %d not
> > > > > > > in
> > > > > > topology, not sending remove\n",
> > > > > > > -                       new_payload->vcpi);
> > > > > > > +                       payload->vcpi);
> > > > > > > +
> > > > > > > +   payload->payload_allocation_status =
> > > > > > > +DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL;
> > > > > > > +}
> > > > > > > +EXPORT_SYMBOL(drm_dp_remove_payload_part1);
> > > > > > >
> > > > > > > +/**
> > > > > > > + * drm_dp_remove_payload_part2() - Remove an MST payload
> > > > > > > +locally
> > > > > > > + * @mgr: Manager to use.
> > > > > > > + * @mst_state: The MST atomic state
> > > > > > > + * @old_payload: The payload with its old state
> > > > > > > + * @new_payload: The payload with its latest state
> > > > > > > + *
> > > > > > > + * Updates the starting time slots of all other payloads
> > > > > > > +which would have been shifted towards
> > > > > > > + * the start of the payload ID table as a result of
> > > > > > > +removing a payload. Driver should call this
> > > > > > > + * function whenever it removes a payload in its HW. It's
> > > > > > > +independent to the result of payload
> > > > > > > + * allocation/deallocation at branch devices along the virtual
> channel.
> > > > > > > + */
> > > > > > > +void drm_dp_remove_payload_part2(struct
> > > > drm_dp_mst_topology_mgr
> > > > > > *mgr,
> > > > > > > +                            struct
> > > > > > > + drm_dp_mst_topology_state
> > > > > > *mst_state,
> > > > > > > +                            const struct
> > > > > > > + drm_dp_mst_atomic_payload
> > > > > > *old_payload,
> > > > > > > +                            struct
> > > > > > > + drm_dp_mst_atomic_payload
> > > > > > *new_payload) {
> > > > > > > +   struct drm_dp_mst_atomic_payload *pos;
> > > > > > > +
> > > > > > > +   /* Remove local payload allocation */
> > > > > > >     list_for_each_entry(pos, &mst_state->payloads, next) {
> > > > > > >             if (pos != new_payload && pos->vc_start_slot >
> > > > > > > new_payload-
> > > > > > > vc_start_slot)
> > > > > > >                     pos->vc_start_slot -=
> > > > > > > old_payload->time_slots; @@ -
> > > > > > 3382,9 +3409,10
> > > > > > > @@ void drm_dp_remove_payload(struct
> drm_dp_mst_topology_mgr
> > > > > > *mgr,
> > > > > > >
> > > > > > >     if (new_payload->delete)
> > > > > > >             drm_dp_mst_put_port_malloc(new_payload->port);
> > > > > > > -}
> > > > > > > -EXPORT_SYMBOL(drm_dp_remove_payload);
> > > > > > >
> > > > > > > +   new_payload->payload_allocation_status =
> > > > > > > +DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
> > > > > > > +}
> > > > > > > +EXPORT_SYMBOL(drm_dp_remove_payload_part2);
> > > > > > >  /**
> > > > > > >   * drm_dp_add_payload_part2() - Execute payload update part 2
> > > > > > >   * @mgr: Manager to use.
> > > > > > > @@ -3403,17 +3431,19 @@ int
> drm_dp_add_payload_part2(struct
> > > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > > >     int ret = 0;
> > > > > > >
> > > > > > >     /* Skip failed payloads */
> > > > > > > -   if (payload->vc_start_slot == -1) {
> > > > > > > -           drm_dbg_kms(mgr->dev, "Part 1 of payload creation for %s
> > > > > > failed, skipping part 2\n",
> > > > > > > +   if (payload->payload_allocation_status !=
> > > > > > DRM_DP_MST_PAYLOAD_ALLOCATION_DFP) {
> > > > > > > +           drm_dbg_kms(state->dev, "Part 1 of payload
> > > > > > > + creation for %s
> > > > > > failed,
> > > > > > > +skipping part 2\n",
> > > > > > >                         payload->port->connector->name);
> > > > > > >             return -EIO;
> > > > > > >     }
> > > > > > >
> > > > > > > -   ret = drm_dp_create_payload_step2(mgr, payload);
> > > > > > > -   if (ret < 0) {
> > > > > > > +   /* Allocate payload to remote end */
> > > > > > > +   ret = drm_dp_create_payload_to_remote(mgr, payload);
> > > > > > > +   if (ret < 0)
> > > > > > >             drm_err(mgr->dev, "Step 2 of creating MST
> > > > > > > payload for %p
> > > > > > failed: %d\n",
> > > > > > >                     payload->port, ret);
> > > > > > > -   }
> > > > > > > +   else
> > > > > > > +           payload->payload_allocation_status =
> > > > > > > +DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE;
> > > > > > >
> > > > > > >     return ret;
> > > > > > >  }
> > > > > > > @@ -4324,6 +4354,7 @@ int
> > > > > > > drm_dp_atomic_find_time_slots(struct
> > > > > > drm_atomic_state *state,
> > > > > > >             drm_dp_mst_get_port_malloc(port);
> > > > > > >             payload->port = port;
> > > > > > >             payload->vc_start_slot = -1;
> > > > > > > +           payload->payload_allocation_status =
> > > > > > > +DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
> > > > > > >             list_add(&payload->next, &topology_state->payloads);
> > > > > > >     }
> > > > > > >     payload->time_slots = req_slots; @@ -4493,7 +4524,7 @@
> > > > > > > void
> > > > > > drm_dp_mst_atomic_wait_for_dependencies(struct
> > > > > > drm_atomic_state
> > > > > > *state)
> > > > > > >             }
> > > > > > >
> > > > > > >             /* Now that previous state is committed, it's
> > > > > > > safe to copy over
> > > > > > the start slot
> > > > > > > -            * assignments
> > > > > > > +            * and allocation status assignments
> > > > > > >              */
> > > > > > >             list_for_each_entry(old_payload,
> > > > > > > &old_mst_state->payloads,
> > > > > > next) {
> > > > > > >                     if (old_payload->delete) @@ -4502,6
> > > > > > > +4533,8 @@ void
> > > > > > drm_dp_mst_atomic_wait_for_dependencies(struct
> > > > > > drm_atomic_state
> > > > > > *state)
> > > > > > >                     new_payload =
> > > > > > drm_atomic_get_mst_payload_state(new_mst_state,
> > > > > > >
> > > > > > old_payload->port);
> > > > > > >                     new_payload->vc_start_slot =
> > > > > > > old_payload- vc_start_slot;
> > > > > > > +                   new_payload->payload_allocation_status =
> > > > > > > +
> > > > > > > + old_payload-
> > > > > > > payload_allocation_status;
> > > > > >
> > > > > > And here. Besides that, I think patches 1/3 and 2/3 look
> > > > > > great! Just finished testing them on nouveau:
> > > > > >
> > > > > > Reviewed-by: Lyude Paul <lyude@redhat.com>
> > > > > >
> > > > > > Patch 3/3 I gotta think about a bit more (and am curious about
> > > > > > Imre's current take on it) I think
> > > > > >
> > > > > > >             }
> > > > > > >     }
> > > > > > >  }
> > > > > > > @@ -4818,6 +4851,13 @@ void
> drm_dp_mst_dump_topology(struct
> > > > > > seq_file *m,
> > > > > > >     struct drm_dp_mst_atomic_payload *payload;
> > > > > > >     int i, ret;
> > > > > > >
> > > > > > > +   static const char *const status[] = {
> > > > > > > +           "None",
> > > > > > > +           "Local",
> > > > > > > +           "DFP",
> > > > > > > +           "Remote",
> > > > > > > +   };
> > > > > > > +
> > > > > > >     mutex_lock(&mgr->lock);
> > > > > > >     if (mgr->mst_primary)
> > > > > > >             drm_dp_mst_dump_mstb(m, mgr->mst_primary); @@ -
> > > > > > 4834,7 +4874,7 @@
> > > > > > > void drm_dp_mst_dump_topology(struct seq_file *m,
> > > > > > >     seq_printf(m, "payload_mask: %x, max_payloads: %d, start_slot:
> > > > > > > %u,
> > > > > > pbn_div: %d\n",
> > > > > > >                state->payload_mask, mgr->max_payloads,
> > > > > > > state- start_slot,
> > > > > > > state->pbn_div);
> > > > > > >
> > > > > > > -   seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc |     sink
> name
> > > > > > > \n");
> > > > > > > +   seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc | status |
> sink
> > > > > > name     |\n");
> > > > > > >     for (i = 0; i < mgr->max_payloads; i++) {
> > > > > > >             list_for_each_entry(payload, &state->payloads, next) {
> > > > > > >                     char name[14]; @@ -4843,7 +4883,7 @@
> > > > > > > void drm_dp_mst_dump_topology(struct
> > > > > > seq_file *m,
> > > > > > >                             continue;
> > > > > > >
> > > > > > >                     fetch_monitor_name(mgr, payload->port,
> > > > > > > name,
> > > > > > sizeof(name));
> > > > > > > -                   seq_printf(m, " %5d %6d %6d %02d - %02d %5d %5s
> > > > > > %19s\n",
> > > > > > > +                   seq_printf(m, " %5d %6d %6d %02d - %02d
> > > > > > > + %5d %5s
> > > > > > %8s %19s\n",
> > > > > > >                                i,
> > > > > > >                                payload->port->port_num,
> > > > > > >                                payload->vcpi, @@ -4851,6
> > > > > > > +4891,7 @@ void drm_dp_mst_dump_topology(struct
> > > > > > seq_file *m,
> > > > > > >                                payload->vc_start_slot +
> > > > > > > payload- time_slots - 1,
> > > > > > >                                payload->pbn,
> > > > > > >                                payload->dsc_enabled ? "Y" :
> > > > > > > "N",
> > > > > > > +
> > > > > > > + status[payload->payload_allocation_status],
> > > > > > >                                (*name != 0) ? name : "Unknown");
> > > > > > >             }
> > > > > > >     }
> > > > > > > diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > > > > > b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > > > > > index e3f176a093d2..5f73cdabe7a1 100644
> > > > > > > --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > > > > > +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > > > > > @@ -557,12 +557,8 @@ static void intel_mst_disable_dp(struct
> > > > > > intel_atomic_state *state,
> > > > > > >     struct intel_dp *intel_dp = &dig_port->dp;
> > > > > > >     struct intel_connector *connector =
> > > > > > >             to_intel_connector(old_conn_state->connector);
> > > > > > > -   struct drm_dp_mst_topology_state *old_mst_state =
> > > > > > > -           drm_atomic_get_old_mst_topology_state(&state->base,
> > > > > > &intel_dp->mst_mgr);
> > > > > > >     struct drm_dp_mst_topology_state *new_mst_state =
> > > > > > >
> > > > > > > drm_atomic_get_new_mst_topology_state(&state->base,
> > > > > > &intel_dp->mst_mgr);
> > > > > > > -   const struct drm_dp_mst_atomic_payload *old_payload =
> > > > > > > -           drm_atomic_get_mst_payload_state(old_mst_state,
> > > > > > connector->port);
> > > > > > >     struct drm_dp_mst_atomic_payload *new_payload =
> > > > > > >             drm_atomic_get_mst_payload_state(new_mst_state,
> > > > > > connector->port);
> > > > > > >     struct drm_i915_private *i915 =
> > > > > > > to_i915(connector->base.dev); @@
> > > > > > > -572,8 +568,7 @@ static void intel_mst_disable_dp(struct
> > > > > > > intel_atomic_state *state,
> > > > > > >
> > > > > > >     intel_hdcp_disable(intel_mst->connector);
> > > > > > >
> > > > > > > -   drm_dp_remove_payload(&intel_dp->mst_mgr, new_mst_state,
> > > > > > > -                         old_payload, new_payload);
> > > > > > > +   drm_dp_remove_payload_part1(&intel_dp->mst_mgr,
> > > > > > new_mst_state,
> > > > > > > +new_payload);
> > > > > > >
> > > > > > >     intel_audio_codec_disable(encoder, old_crtc_state,
> > > > > > > old_conn_state); } @@ -588,6 +583,14 @@ static void
> > > > > > > intel_mst_post_disable_dp(struct intel_atomic_state *state,
> > > > > > >     struct intel_dp *intel_dp = &dig_port->dp;
> > > > > > >     struct intel_connector *connector =
> > > > > > >             to_intel_connector(old_conn_state->connector);
> > > > > > > +   struct drm_dp_mst_topology_state *old_mst_state =
> > > > > > > +
> > > > > > > + drm_atomic_get_old_mst_topology_state(&state->base,
> > > > > > &intel_dp->mst_mgr);
> > > > > > > +   struct drm_dp_mst_topology_state *new_mst_state =
> > > > > > > +
> > > > > > > + drm_atomic_get_new_mst_topology_state(&state->base,
> > > > > > &intel_dp->mst_mgr);
> > > > > > > +   const struct drm_dp_mst_atomic_payload *old_payload =
> > > > > > > +           drm_atomic_get_mst_payload_state(old_mst_state,
> > > > > > connector->port);
> > > > > > > +   struct drm_dp_mst_atomic_payload *new_payload =
> > > > > > > +           drm_atomic_get_mst_payload_state(new_mst_state,
> > > > > > connector->port);
> > > > > > >     struct drm_i915_private *dev_priv = to_i915(connector-
> >base.dev);
> > > > > > >     bool last_mst_stream;
> > > > > > >
> > > > > > > @@ -608,6 +611,9 @@ static void
> > > > > > > intel_mst_post_disable_dp(struct intel_atomic_state *state,
> > > > > > >
> > > > > > >     wait_for_act_sent(encoder, old_crtc_state);
> > > > > > >
> > > > > > > +   drm_dp_remove_payload_part2(&intel_dp->mst_mgr,
> > > > > > new_mst_state,
> > > > > > > +                               old_payload, new_payload);
> > > > > > > +
> > > > > > >     intel_ddi_disable_transcoder_func(old_crtc_state);
> > > > > > >
> > > > > > >     if (DISPLAY_VER(dev_priv) >= 9) diff --git
> > > > > > > a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > > > > > b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > > > > > index 4e7c9c353c51..bba01fa0780c 100644
> > > > > > > --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > > > > > +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > > > > > @@ -882,21 +882,26 @@ struct nouveau_encoder
> > > > > > > *nv50_real_outp(struct drm_encoder *encoder)
> > > > > > >
> > > > > > >  static void
> > > > > > >  nv50_msto_cleanup(struct drm_atomic_state *state,
> > > > > > > -             struct drm_dp_mst_topology_state *mst_state,
> > > > > > > +             struct drm_dp_mst_topology_state
> > > > > > > + *new_mst_state,
> > > > > > >               struct drm_dp_mst_topology_mgr *mgr,
> > > > > > >               struct nv50_msto *msto)  {
> > > > > > >     struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
> > > > > > > -   struct drm_dp_mst_atomic_payload *payload =
> > > > > > > -           drm_atomic_get_mst_payload_state(mst_state, msto->mstc-
> > > > > > > port);
> > > > > > > +   struct drm_dp_mst_atomic_payload *new_payload =
> > > > > > > +           drm_atomic_get_mst_payload_state(new_mst_state,
> > > > > > > + msto-
> > > > > > > mstc->port);
> > > > > > > +   struct drm_dp_mst_topology_state *old_mst_state =
> > > > > > > +           drm_atomic_get_old_mst_topology_state(state, mgr);
> > > > > > > +   const struct drm_dp_mst_atomic_payload *old_payload =
> > > > > > > +           drm_atomic_get_mst_payload_state(old_mst_state,
> > > > > > > + msto-
> > > > > > > mstc->port);
> > > > > > >
> > > > > > >     NV_ATOMIC(drm, "%s: msto cleanup\n",
> > > > > > > msto->encoder.name);
> > > > > > >
> > > > > > >     if (msto->disabled) {
> > > > > > >             msto->mstc = NULL;
> > > > > > >             msto->disabled = false;
> > > > > > > +           drm_dp_remove_payload_part2(mgr, new_mst_state,
> > > > > > old_payload,
> > > > > > > +new_payload);
> > > > > > >     } else if (msto->enabled) {
> > > > > > > -           drm_dp_add_payload_part2(mgr, state, payload);
> > > > > > > +           drm_dp_add_payload_part2(mgr, state,
> > > > > > > + new_payload);
> > > > > > >             msto->enabled = false;
> > > > > > >     }
> > > > > > >  }
> > > > > > > @@ -910,19 +915,15 @@ nv50_msto_prepare(struct
> > > > > > > drm_atomic_state
> > > > > > *state,
> > > > > > >     struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
> > > > > > >     struct nv50_mstc *mstc = msto->mstc;
> > > > > > >     struct nv50_mstm *mstm = mstc->mstm;
> > > > > > > -   struct drm_dp_mst_topology_state *old_mst_state;
> > > > > > > -   struct drm_dp_mst_atomic_payload *payload, *old_payload;
> > > > > > > +   struct drm_dp_mst_atomic_payload *payload;
> > > > > > >
> > > > > > >     NV_ATOMIC(drm, "%s: msto prepare\n",
> > > > > > > msto->encoder.name);
> > > > > > >
> > > > > > > -   old_mst_state = drm_atomic_get_old_mst_topology_state(state,
> > > > > > mgr);
> > > > > > > -
> > > > > > >     payload = drm_atomic_get_mst_payload_state(mst_state,
> > > > > > > mstc- port);
> > > > > > > -   old_payload =
> drm_atomic_get_mst_payload_state(old_mst_state,
> > > > > > mstc->port);
> > > > > > >
> > > > > > >     // TODO: Figure out if we want to do a better job of
> > > > > > > handling VCPI
> > > > > > allocation failures here?
> > > > > > >     if (msto->disabled) {
> > > > > > > -           drm_dp_remove_payload(mgr, mst_state, old_payload,
> > > > > > payload);
> > > > > > > +           drm_dp_remove_payload_part1(mgr, mst_state,
> > > > > > > + payload);
> > > > > > >
> > > > > > >             nvif_outp_dp_mst_vcpi(&mstm->outp->outp,
> > > > > > > msto->head- base.index, 0, 0, 0, 0);
> > > > > > >     } else {
> > > > > > > diff --git a/include/drm/display/drm_dp_mst_helper.h
> > > > > > > b/include/drm/display/drm_dp_mst_helper.h
> > > > > > > index ed5c9660563c..4429d3b1745b 100644
> > > > > > > --- a/include/drm/display/drm_dp_mst_helper.h
> > > > > > > +++ b/include/drm/display/drm_dp_mst_helper.h
> > > > > > > @@ -46,6 +46,13 @@ struct drm_dp_mst_topology_ref_history {
> > > > > > > }; #endif /*
> > > > IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) */
> > > > > > >
> > > > > > > +enum drm_dp_mst_payload_allocation {
> > > > > > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_NONE,
> > > > > > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL,
> > > > > > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_DFP,
> > > > > > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE,
> > > > > > > +};
> > > > > > > +
> > > > > > >  struct drm_dp_mst_branch;
> > > > > > >
> > > > > > >  /**
> > > > > > > @@ -537,7 +544,7 @@ struct drm_dp_mst_atomic_payload {
> > > > > > >      *   drm_dp_mst_atomic_wait_for_dependencies() has been
> called,
> > > > > > which will ensure the
> > > > > > >      *   previous MST states payload start slots have been copied over
> to
> > > > > > the new state. Note
> > > > > > >      *   that a new start slot won't be assigned/removed from this
> payload
> > > > > > until
> > > > > > > -    *   drm_dp_add_payload_part1()/drm_dp_remove_payload()
> have
> > > > > > been called.
> > > > > > > +    *
> drm_dp_add_payload_part1()/drm_dp_remove_payload_part2()
> > > > > > have been called.
> > > > > > >      * * Acquire the MST modesetting lock, and then wait for
> > > > > > > any pending
> > > > > > MST-related commits to
> > > > > > >      *   get committed to hardware by calling drm_crtc_commit_wait()
> on
> > > > > > each of the
> > > > > > >      *   &drm_crtc_commit structs in
> > > > > > &drm_dp_mst_topology_state.commit_deps.
> > > > > > > @@ -564,6 +571,9 @@ struct drm_dp_mst_atomic_payload {
> > > > > > >     /** @dsc_enabled: Whether or not this payload has DSC enabled
> */
> > > > > > >     bool dsc_enabled : 1;
> > > > > > >
> > > > > > > +   /** @payload_allocation_status: The allocation status of
> > > > > > > + this payload
> > > > > > */
> > > > > > > +   enum drm_dp_mst_payload_allocation
> > > > > > > + payload_allocation_status;
> > > > > > > +
> > > > > > >     /** @next: The list node for this payload */
> > > > > > >     struct list_head next;
> > > > > > >  };
> > > > > > > @@ -842,10 +852,13 @@ int drm_dp_add_payload_part1(struct
> > > > > > > drm_dp_mst_topology_mgr *mgr,  int
> > > > drm_dp_add_payload_part2(struct
> > > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > > >                          struct drm_atomic_state *state,
> > > > > > >                          struct drm_dp_mst_atomic_payload
> > > > > > > *payload); -
> > > > > > void
> > > > > > > drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
> > > > > > > -                      struct drm_dp_mst_topology_state *mst_state,
> > > > > > > -                      const struct drm_dp_mst_atomic_payload
> > > > > > *old_payload,
> > > > > > > -                      struct drm_dp_mst_atomic_payload
> > > > > > *new_payload);
> > > > > > > +void drm_dp_remove_payload_part1(struct
> > > > drm_dp_mst_topology_mgr
> > > > > > *mgr,
> > > > > > > +                            struct
> > > > > > > + drm_dp_mst_topology_state
> > > > > > *mst_state,
> > > > > > > +                            struct
> > > > > > > + drm_dp_mst_atomic_payload
> > > > > > *payload); void
> > > > > > > +drm_dp_remove_payload_part2(struct
> drm_dp_mst_topology_mgr
> > > > *mgr,
> > > > > > > +                            struct
> > > > > > > + drm_dp_mst_topology_state
> > > > > > *mst_state,
> > > > > > > +                            const struct
> > > > > > > + drm_dp_mst_atomic_payload
> > > > > > *old_payload,
> > > > > > > +                            struct
> > > > > > > + drm_dp_mst_atomic_payload
> > > > > > *new_payload);
> > > > > > >
> > > > > > >  int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr
> > > > > > > *mgr);
> > > > > > >
> > > > > >
> > > > > > --
> > > > > > Cheers,
> > > > > >  Lyude Paul (she/her)
> > > > > >  Software Engineer at Red Hat
> > > > > --
> > > > > Regards,
> > > > > Wayne
> > > >
> > > > --
> > > > Cheers,
> > > >  Lyude Paul (she/her)
> > > >  Software Engineer at Red Hat
> > > --
> > > Regards,
> > > Wayne
> > >
> >
> > --
> > Cheers,
> >  Lyude Paul (she/her)
> >  Software Engineer at Red Hat
> >

Re: [Patch v2 2/3] drm/mst: Refactor the flow for payload allocation/removement

[Imre Deak]

On Mon, Sep 04, 2023 at 06:58:20AM +0000, Lin, Wayne wrote:
> [Public]
> 
> Thank you Lyude and Alex!

This patch had i915 changes, please also Cc the
intel-gfx@lists.freedesktop.org list for such patchsets, so that
we get CI test results for it.

Also, I think patches with i915 changes need an Ack from an i915
developer before pushing.

Thanks,
Imre

> Regards,
> Wayne
> > -----Original Message-----
> > From: Alex Deucher <alexdeucher@gmail.com>
> > Sent: Saturday, September 2, 2023 3:38 AM
> > To: Lyude Paul <lyude@redhat.com>
> > Cc: Lin, Wayne <Wayne.Lin@amd.com>; dri-devel@lists.freedesktop.org;
> > amd-gfx@lists.freedesktop.org; jani.nikula@intel.com; imre.deak@intel.com;
> > Wentland, Harry <Harry.Wentland@amd.com>; Zuo, Jerry
> > <Jerry.Zuo@amd.com>; ville.syrjala@linux.intel.com
> > Subject: Re: [Patch v2 2/3] drm/mst: Refactor the flow for payload
> > allocation/removement
> >
> > On Thu, Aug 31, 2023 at 6:45 PM Lyude Paul <lyude@redhat.com> wrote:
> > >
> > > On Thu, 2023-08-24 at 04:12 +0000, Lin, Wayne wrote:
> > > > [Public]
> > > >
> > > > Hi Lyude,
> > > >
> > > > I'm afraid that I don't have the permissions to push and would like
> > > > to have your help. Thanks!
> > >
> > > Whoops, sorry I only just noticed this message. I set a reminder on my
> > > phone to bug me to push it tomorrow :), sorry about the delay
> > >
> >
> > Wayne, I don't see why we couldn't give you commit permissions for drm-
> > misc.
> >
> > Alex
> >
> > > >
> > > > > -----Original Message-----
> > > > > From: Lyude Paul <lyude@redhat.com>
> > > > > Sent: Thursday, August 24, 2023 5:00 AM
> > > > > To: Lin, Wayne <Wayne.Lin@amd.com>;
> > > > > dri-devel@lists.freedesktop.org; amd-gfx@lists.freedesktop.org
> > > > > Cc: jani.nikula@intel.com; ville.syrjala@linux.intel.com;
> > > > > imre.deak@intel.com; Wentland, Harry <Harry.Wentland@amd.com>;
> > > > > Zuo, Jerry <Jerry.Zuo@amd.com>
> > > > > Subject: Re: [Patch v2 2/3] drm/mst: Refactor the flow for payload
> > > > > allocation/removement
> > > > >
> > > > > Sure - you're also welcome to push the first two patches after
> > > > > fixing the indentation if you'd like
> > > > >
> > > > > On Wed, 2023-08-23 at 03:19 +0000, Lin, Wayne wrote:
> > > > > > [Public]
> > > > > >
> > > > > > Thanks, Lyude!
> > > > > > Should I push another version to fix the indention?
> > > > > >
> > > > > > > -----Original Message-----
> > > > > > > From: Lyude Paul <lyude@redhat.com>
> > > > > > > Sent: Friday, August 18, 2023 6:17 AM
> > > > > > > To: Lin, Wayne <Wayne.Lin@amd.com>;
> > > > > > > dri-devel@lists.freedesktop.org; amd-gfx@lists.freedesktop.org
> > > > > > > Cc: jani.nikula@intel.com; ville.syrjala@linux.intel.com;
> > > > > > > imre.deak@intel.com; Wentland, Harry <Harry.Wentland@amd.com>;
> > > > > > > Zuo, Jerry <Jerry.Zuo@amd.com>
> > > > > > > Subject: Re: [Patch v2 2/3] drm/mst: Refactor the flow for
> > > > > > > payload allocation/removement
> > > > > > >
> > > > > > > Two small comments:
> > > > > > >
> > > > > > > On Mon, 2023-08-07 at 10:56 +0800, Wayne Lin wrote:
> > > > > > > > [Why]
> > > > > > > > Today, the allocation/deallocation steps and status is a bit unclear.
> > > > > > > >
> > > > > > > > For instance, payload->vc_start_slot = -1 stands for "the
> > > > > > > > failure of updating DPCD payload ID table" and can also
> > > > > > > > represent as "payload is not allocated yet". These two cases
> > > > > > > > should be handled differently and hence better to distinguish them
> > for better understanding.
> > > > > > > >
> > > > > > > > [How]
> > > > > > > > Define enumeration - ALLOCATION_LOCAL, ALLOCATION_DFP and
> > > > > > > > ALLOCATION_REMOTE to distinguish different allocation status.
> > > > > > > > Adjust the code to handle different status accordingly for
> > > > > > > > better understanding the sequence of payload allocation and
> > > > > > > > payload
> > > > > > > removement.
> > > > > > > >
> > > > > > > > For payload creation, the procedure should look like this:
> > > > > > > > DRM part 1:
> > > > > > > > * step 1 - update sw mst mgr variables to add a new payload
> > > > > > > > * step 2 - add payload at immediate DFP DPCD payload table
> > > > > > > >
> > > > > > > > Driver:
> > > > > > > > * Add new payload in HW and sync up with DFP by sending ACT
> > > > > > > >
> > > > > > > > DRM Part 2:
> > > > > > > > * Send ALLOCATE_PAYLOAD sideband message to allocate
> > > > > > > > bandwidth along
> > > > > > > the
> > > > > > > >   virtual channel.
> > > > > > > >
> > > > > > > > And as for payload removement, the procedure should look like this:
> > > > > > > > DRM part 1:
> > > > > > > > * step 1 - Send ALLOCATE_PAYLOAD sideband message to release
> > > > > bandwidth
> > > > > > > >            along the virtual channel
> > > > > > > > * step 2 - Clear payload allocation at immediate DFP DPCD
> > > > > > > > payload table
> > > > > > > >
> > > > > > > > Driver:
> > > > > > > > * Remove the payload in HW and sync up with DFP by sending
> > > > > > > > ACT
> > > > > > > >
> > > > > > > > DRM part 2:
> > > > > > > > * update sw mst mgr variables to remove the payload
> > > > > > > >
> > > > > > > > Note that it's fine to fail when communicate with the branch
> > > > > > > > device connected at immediate downstrean-facing port, but
> > > > > > > > updating variables of SW mst mgr and HW configuration should
> > > > > > > > be conducted anyway. That's because it's under commit_tail
> > > > > > > > and we need to complete the HW
> > > > > > > programming.
> > > > > > > >
> > > > > > > > Changes since v1:
> > > > > > > > * Remove the set but not use variable 'old_payload' in function
> > > > > > > >   'nv50_msto_prepare'. Catched by kernel test robot
> > > > > > > > <lkp@intel.com>
> > > > > > > >
> > > > > > > > Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
> > > > > > > > ---
> > > > > > > >  .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c |  20 ++-
> > > > > > > > drivers/gpu/drm/display/drm_dp_mst_topology.c | 159
> > > > > > > > +++++++++++------
> > > > > > > -
> > > > > > > >  drivers/gpu/drm/i915/display/intel_dp_mst.c   |  18 +-
> > > > > > > >  drivers/gpu/drm/nouveau/dispnv50/disp.c       |  21 +--
> > > > > > > >  include/drm/display/drm_dp_mst_helper.h       |  23 ++-
> > > > > > > >  5 files changed, 153 insertions(+), 88 deletions(-)
> > > > > > > >
> > > > > > > > diff --git
> > > > > > >
> > a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > > > > > >
> > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > > > > > > index d9a482908380..9ad509279b0a 100644
> > > > > > > > ---
> > > > > > > >
> > a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > > > > > > +++
> > > > > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > > > > > > > @@ -219,7 +219,7 @@ static void
> > dm_helpers_construct_old_payload(
> > > > > > > >     /* Set correct time_slots/PBN of old payload.
> > > > > > > >      * other fields (delete & dsc_enabled) in
> > > > > > > >      * struct drm_dp_mst_atomic_payload are don't care fields
> > > > > > > > -    * while calling drm_dp_remove_payload()
> > > > > > > > +    * while calling drm_dp_remove_payload_part2()
> > > > > > > >      */
> > > > > > > >     for (i = 0; i < current_link_table.stream_count; i++) {
> > > > > > > >             dc_alloc =
> > > > > > > > @@ -262,13 +262,12 @@ bool
> > > > > > > > dm_helpers_dp_mst_write_payload_allocation_table(
> > > > > > > >
> > > > > > > >     mst_mgr = &aconnector->mst_root->mst_mgr;
> > > > > > > >     mst_state =
> > > > > > > > to_drm_dp_mst_topology_state(mst_mgr->base.state);
> > > > > > > > -
> > > > > > > > -   /* It's OK for this to fail */
> > > > > > > >     new_payload =
> > > > > > > > drm_atomic_get_mst_payload_state(mst_state,
> > > > > > > > aconnector->mst_output_port);
> > > > > > > >
> > > > > > > >     if (enable) {
> > > > > > > >             target_payload = new_payload;
> > > > > > > >
> > > > > > > > +           /* It's OK for this to fail */
> > > > > > > >             drm_dp_add_payload_part1(mst_mgr, mst_state,
> > > > > > > new_payload);
> > > > > > > >     } else {
> > > > > > > >             /* construct old payload by VCPI*/ @@ -276,7
> > > > > > > > +275,7 @@ bool
> > > > > > > dm_helpers_dp_mst_write_payload_allocation_table(
> > > > > > > >                                             new_payload, &old_payload);
> > > > > > > >             target_payload = &old_payload;
> > > > > > > >
> > > > > > > > -           drm_dp_remove_payload(mst_mgr, mst_state,
> > > > > > > &old_payload, new_payload);
> > > > > > > > +           drm_dp_remove_payload_part1(mst_mgr, mst_state,
> > > > > > > new_payload);
> > > > > > > >     }
> > > > > > > >
> > > > > > > >     /* mst_mgr->->payloads are VC payload notify MST branch
> > > > > > > > using
> > > > > > > DPCD
> > > > > > > > or @@ -342,7 +341,7 @@ bool
> > > > > > > dm_helpers_dp_mst_send_payload_allocation(
> > > > > > > >     struct amdgpu_dm_connector *aconnector;
> > > > > > > >     struct drm_dp_mst_topology_state *mst_state;
> > > > > > > >     struct drm_dp_mst_topology_mgr *mst_mgr;
> > > > > > > > -   struct drm_dp_mst_atomic_payload *payload;
> > > > > > > > +   struct drm_dp_mst_atomic_payload *new_payload,
> > > > > > > > + *old_payload;
> > > > > > > >     enum mst_progress_status set_flag =
> > > > > > > MST_ALLOCATE_NEW_PAYLOAD;
> > > > > > > >     enum mst_progress_status clr_flag =
> > > > > > > MST_CLEAR_ALLOCATED_PAYLOAD;
> > > > > > > >     int ret = 0;
> > > > > > > > @@ -355,15 +354,20 @@ bool
> > > > > > > dm_helpers_dp_mst_send_payload_allocation(
> > > > > > > >     mst_mgr = &aconnector->mst_root->mst_mgr;
> > > > > > > >     mst_state =
> > > > > > > > to_drm_dp_mst_topology_state(mst_mgr->base.state);
> > > > > > > >
> > > > > > > > -   payload = drm_atomic_get_mst_payload_state(mst_state,
> > > > > > > aconnector->mst_output_port);
> > > > > > > > +   new_payload =
> > > > > > > > + drm_atomic_get_mst_payload_state(mst_state,
> > > > > > > > +aconnector->mst_output_port);
> > > > > > > >
> > > > > > > >     if (!enable) {
> > > > > > > >             set_flag = MST_CLEAR_ALLOCATED_PAYLOAD;
> > > > > > > >             clr_flag = MST_ALLOCATE_NEW_PAYLOAD;
> > > > > > > >     }
> > > > > > > >
> > > > > > > > -   if (enable)
> > > > > > > > -           ret = drm_dp_add_payload_part2(mst_mgr, mst_state-
> > > > > > > > base.state, payload);
> > > > > > > > +   if (enable) {
> > > > > > > > +           ret = drm_dp_add_payload_part2(mst_mgr,
> > > > > > > > + mst_state-
> > > > > > > > base.state, new_payload);
> > > > > > > > +   } else {
> > > > > > > > +           dm_helpers_construct_old_payload(stream->link,
> > > > > > > > + mst_state-
> > > > > > > > pbn_div,
> > > > > > > > +                                            new_payload, old_payload);
> > > > > > > > +           drm_dp_remove_payload_part2(mst_mgr, mst_state,
> > > > > > > old_payload, new_payload);
> > > > > > > > +   }
> > > > > > > >
> > > > > > > >     if (ret) {
> > > > > > > >
> > > > > > > > amdgpu_dm_set_mst_status(&aconnector->mst_status,
> > > > > > > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > > > > > > b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > > > > > > index 4d80426757ab..e04f87ff755a 100644
> > > > > > > > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > > > > > > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > > > > > > > @@ -3255,15 +3255,15 @@ int
> > > > > > > drm_dp_send_query_stream_enc_status(struct
> > > > > > > > drm_dp_mst_topology_mgr *mgr,  }
> > > > > > > > EXPORT_SYMBOL(drm_dp_send_query_stream_enc_status);
> > > > > > > >
> > > > > > > > -static int drm_dp_create_payload_step1(struct
> > > > > > > > drm_dp_mst_topology_mgr
> > > > > > > *mgr,
> > > > > > > > -                                  struct drm_dp_mst_atomic_payload
> > > > > > > *payload)
> > > > > > > > +static int drm_dp_create_payload_at_dfp(struct
> > > > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > > > > +                                   struct
> > > > > > > > + drm_dp_mst_atomic_payload
> > > > > > > *payload)
> > > > > > > >  {
> > > > > > > >     return drm_dp_dpcd_write_payload(mgr, payload->vcpi,
> > > > > > > > payload- vc_start_slot,
> > > > > > > >                                      payload->time_slots);
> > > > > > > > }
> > > > > > > >
> > > > > > > > -static int drm_dp_create_payload_step2(struct
> > > > > > > > drm_dp_mst_topology_mgr
> > > > > > > *mgr,
> > > > > > > > -                                  struct drm_dp_mst_atomic_payload
> > > > > > > *payload)
> > > > > > > > +static int drm_dp_create_payload_to_remote(struct
> > > > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > > > > +                                      struct
> > > > > > > > + drm_dp_mst_atomic_payload
> > > > > > > *payload)
> > > > > > > >  {
> > > > > > > >     int ret;
> > > > > > > >     struct drm_dp_mst_port *port =
> > > > > > > > drm_dp_mst_topology_get_port_validated(mgr, payload->port);
> > > > > > > > @@ -
> > > > > > > 3276,17 +3276,20 @@ static int
> > > > > > > drm_dp_create_payload_step2(struct
> > > > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > > > >     return ret;
> > > > > > > >  }
> > > > > > > >
> > > > > > > > -static int drm_dp_destroy_payload_step1(struct
> > > > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > > > > -                                   struct drm_dp_mst_topology_state
> > > > > > > *mst_state,
> > > > > > > > -                                   struct drm_dp_mst_atomic_payload
> > > > > > > *payload)
> > > > > > > > +static void drm_dp_destroy_payload_at_remote_and_dfp(struct
> > > > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > > > > +                                                struct
> > > > > > > drm_dp_mst_topology_state *mst_state,
> > > > > > > > +                                                struct
> > > > > > > drm_dp_mst_atomic_payload *payload)
> > > > > > > >  {
> > > > > > > >     drm_dbg_kms(mgr->dev, "\n");
> > > > > > > >
> > > > > > > >     /* it's okay for these to fail */
> > > > > > > > -   drm_dp_payload_send_msg(mgr, payload->port, payload->vcpi,
> > 0);
> > > > > > > > -   drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload-
> > > > > > > > vc_start_slot, 0);
> > > > > > > > +   if (payload->payload_allocation_status ==
> > > > > > > DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE) {
> > > > > > > > +           drm_dp_payload_send_msg(mgr, payload->port,
> > > > > > > > + payload-
> > > > > > > > vcpi, 0);
> > > > > > > > +           payload->payload_allocation_status =
> > > > > > > DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
> > > > > > > > +   }
> > > > > > > >
> > > > > > > > -   return 0;
> > > > > > > > +   if (payload->payload_allocation_status ==
> > > > > > > DRM_DP_MST_PAYLOAD_ALLOCATION_DFP)
> > > > > > > > +           drm_dp_dpcd_write_payload(mgr, payload->vcpi,
> > > > > > > > +payload->vc_start_slot, 0);
> > > > > > > >  }
> > > > > > > >
> > > > > > > >  /**
> > > > > > > > @@ -3296,81 +3299,105 @@ static int
> > > > > > > drm_dp_destroy_payload_step1(struct drm_dp_mst_topology_mgr
> > > > > > > *mgr,
> > > > > > > >   * @payload: The payload to write
> > > > > > > >   *
> > > > > > > >   * Determines the starting time slot for the given payload,
> > > > > > > > and programs the VCPI for this payload
> > > > > > > > - * into hardware. After calling this, the driver should
> > > > > > > > generate ACT and
> > > > > > > payload packets.
> > > > > > > > + * into the DPCD of DPRX. After calling this, the driver
> > > > > > > > + should generate ACT
> > > > > > > and payload packets.
> > > > > > > >   *
> > > > > > > > - * Returns: 0 on success, error code on failure. In the
> > > > > > > > event that this fails,
> > > > > > > > - * @payload.vc_start_slot will also be set to -1.
> > > > > > > > + * Returns: 0 on success, error code on failure.
> > > > > > > >   */
> > > > > > > >  int drm_dp_add_payload_part1(struct drm_dp_mst_topology_mgr
> > > > > *mgr,
> > > > > > > >                          struct drm_dp_mst_topology_state *mst_state,
> > > > > > > >                          struct drm_dp_mst_atomic_payload *payload)  {
> > > > > > > >     struct drm_dp_mst_port *port;
> > > > > > > > -   int ret;
> > > > > > > > +   int ret = 0;
> > > > > > > > +   bool allocate = true;
> > > > > > > > +
> > > > > > > > +   /* Update mst mgr info */
> > > > > > > > +   if (mgr->payload_count == 0)
> > > > > > > > +           mgr->next_start_slot = mst_state->start_slot;
> > > > > > > > +
> > > > > > > > +   payload->vc_start_slot = mgr->next_start_slot;
> > > > > > > > +
> > > > > > > > +   mgr->payload_count++;
> > > > > > > > +   mgr->next_start_slot += payload->time_slots;
> > > > > > > >
> > > > > > > > +   /* Allocate payload to immediate downstream facing port
> > > > > > > > + */
> > > > > > > >     port = drm_dp_mst_topology_get_port_validated(mgr,
> > > > > > > > payload- port);
> > > > > > > >     if (!port) {
> > > > > > > >             drm_dbg_kms(mgr->dev,
> > > > > > > > -                       "VCPI %d for port %p not in topology, not creating a
> > > > > > > payload\n",
> > > > > > > > +                       "VCPI %d for port %p not in
> > > > > > > > + topology, not creating a
> > > > > > > payload
> > > > > > > > +to remote\n",
> > > > > > > >                         payload->vcpi, payload->port);
> > > > > > > > -           payload->vc_start_slot = -1;
> > > > > > > > -           return 0;
> > > > > > > > +           allocate = false;
> > > > > > > >     }
> > > > > > > >
> > > > > > > > -   if (mgr->payload_count == 0)
> > > > > > > > -           mgr->next_start_slot = mst_state->start_slot;
> > > > > > > > -
> > > > > > > > -   payload->vc_start_slot = mgr->next_start_slot;
> > > > > > > > +   if (allocate) {
> > > > > > > > +           ret = drm_dp_create_payload_at_dfp(mgr, payload);
> > > > > > > > +           if (ret < 0)
> > > > > > > > +                   drm_warn(mgr->dev, "Failed to create MST
> > > > > > > > + payload
> > > > > > > for port %p: %d\n",
> > > > > > > > +                            payload->port, ret);
> > > > > > > >
> > > > > > > > -   ret = drm_dp_create_payload_step1(mgr, payload);
> > > > > > > > -   drm_dp_mst_topology_put_port(port);
> > > > > > > > -   if (ret < 0) {
> > > > > > > > -           drm_warn(mgr->dev, "Failed to create MST payload for port
> > > > > > > %p: %d\n",
> > > > > > > > -                    payload->port, ret);
> > > > > > > > -           payload->vc_start_slot = -1;
> > > > > > > > -           return ret;
> > > > > > > >     }
> > > > > > > >
> > > > > > > > -   mgr->payload_count++;
> > > > > > > > -   mgr->next_start_slot += payload->time_slots;
> > > > > > > > +   payload->payload_allocation_status =
> > > > > > > > +           (!allocate || ret < 0) ?
> > > > > > > DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL :
> > > > > > > > +
> > > > > > >       DRM_DP_MST_PAYLOAD_ALLOCATION_DFP;
> > > > > > >
> > > > > > > Just need to fix indenting here
> > > > > > >
> > > > > > > >
> > > > > > > > -   return 0;
> > > > > > > > +   drm_dp_mst_topology_put_port(port);
> > > > > > > > +
> > > > > > > > +   return ret;
> > > > > > > >  }
> > > > > > > >  EXPORT_SYMBOL(drm_dp_add_payload_part1);
> > > > > > > >
> > > > > > > >  /**
> > > > > > > > - * drm_dp_remove_payload() - Remove an MST payload
> > > > > > > > + * drm_dp_remove_payload_part1() - Remove an MST payload
> > > > > > > > + along the virtual channel
> > > > > > > >   * @mgr: Manager to use.
> > > > > > > >   * @mst_state: The MST atomic state
> > > > > > > > - * @old_payload: The payload with its old state
> > > > > > > > - * @new_payload: The payload to write
> > > > > > > > + * @payload: The payload to remove
> > > > > > > >   *
> > > > > > > > - * Removes a payload from an MST topology if it was
> > > > > > > > successfully assigned a start slot. Also updates
> > > > > > > > - * the starting time slots of all other payloads which
> > > > > > > > would have been shifted towards the start of
> > > > > > > > - * the VC table as a result. After calling this, the driver
> > > > > > > > should generate ACT
> > > > > > > and payload packets.
> > > > > > > > + * Removes a payload along the virtual channel if it was
> > > > > > > > + successfully
> > > > > > > allocated.
> > > > > > > > + * After calling this, the driver should set HW to generate
> > > > > > > > + ACT and then switch to new
> > > > > > > > + * payload allocation state.
> > > > > > > >   */
> > > > > > > > -void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr
> > *mgr,
> > > > > > > > -                      struct drm_dp_mst_topology_state *mst_state,
> > > > > > > > -                      const struct drm_dp_mst_atomic_payload
> > > > > > > *old_payload,
> > > > > > > > -                      struct drm_dp_mst_atomic_payload *new_payload)
> > > > > > > > +void drm_dp_remove_payload_part1(struct
> > > > > drm_dp_mst_topology_mgr
> > > > > > > *mgr,
> > > > > > > > +                            struct
> > > > > > > > + drm_dp_mst_topology_state
> > > > > > > *mst_state,
> > > > > > > > +                            struct
> > > > > > > > + drm_dp_mst_atomic_payload
> > > > > > > *payload)
> > > > > > > >  {
> > > > > > > > -   struct drm_dp_mst_atomic_payload *pos;
> > > > > > > > +   /* Remove remote payload allocation */
> > > > > > > >     bool send_remove = false;
> > > > > > > >
> > > > > > > > -   /* We failed to make the payload, so nothing to do */
> > > > > > > > -   if (new_payload->vc_start_slot == -1)
> > > > > > > > -           return;
> > > > > > > > -
> > > > > > > >     mutex_lock(&mgr->lock);
> > > > > > > > -   send_remove =
> > > > > > > drm_dp_mst_port_downstream_of_branch(new_payload->port,
> > mgr-
> > > > > > > > mst_primary);
> > > > > > > > +   send_remove =
> > > > > > > > + drm_dp_mst_port_downstream_of_branch(payload-
> > > > > > > > port,
> > > > > > > > +mgr->mst_primary);
> > > > > > > >     mutex_unlock(&mgr->lock);
> > > > > > > >
> > > > > > > >     if (send_remove)
> > > > > > > > -           drm_dp_destroy_payload_step1(mgr, mst_state,
> > > > > > > new_payload);
> > > > > > > > +           drm_dp_destroy_payload_at_remote_and_dfp(mgr,
> > > > > > > mst_state, payload);
> > > > > > > >     else
> > > > > > > >             drm_dbg_kms(mgr->dev, "Payload for VCPI %d not
> > > > > > > > in
> > > > > > > topology, not sending remove\n",
> > > > > > > > -                       new_payload->vcpi);
> > > > > > > > +                       payload->vcpi);
> > > > > > > > +
> > > > > > > > +   payload->payload_allocation_status =
> > > > > > > > +DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL;
> > > > > > > > +}
> > > > > > > > +EXPORT_SYMBOL(drm_dp_remove_payload_part1);
> > > > > > > >
> > > > > > > > +/**
> > > > > > > > + * drm_dp_remove_payload_part2() - Remove an MST payload
> > > > > > > > +locally
> > > > > > > > + * @mgr: Manager to use.
> > > > > > > > + * @mst_state: The MST atomic state
> > > > > > > > + * @old_payload: The payload with its old state
> > > > > > > > + * @new_payload: The payload with its latest state
> > > > > > > > + *
> > > > > > > > + * Updates the starting time slots of all other payloads
> > > > > > > > +which would have been shifted towards
> > > > > > > > + * the start of the payload ID table as a result of
> > > > > > > > +removing a payload. Driver should call this
> > > > > > > > + * function whenever it removes a payload in its HW. It's
> > > > > > > > +independent to the result of payload
> > > > > > > > + * allocation/deallocation at branch devices along the virtual
> > channel.
> > > > > > > > + */
> > > > > > > > +void drm_dp_remove_payload_part2(struct
> > > > > drm_dp_mst_topology_mgr
> > > > > > > *mgr,
> > > > > > > > +                            struct
> > > > > > > > + drm_dp_mst_topology_state
> > > > > > > *mst_state,
> > > > > > > > +                            const struct
> > > > > > > > + drm_dp_mst_atomic_payload
> > > > > > > *old_payload,
> > > > > > > > +                            struct
> > > > > > > > + drm_dp_mst_atomic_payload
> > > > > > > *new_payload) {
> > > > > > > > +   struct drm_dp_mst_atomic_payload *pos;
> > > > > > > > +
> > > > > > > > +   /* Remove local payload allocation */
> > > > > > > >     list_for_each_entry(pos, &mst_state->payloads, next) {
> > > > > > > >             if (pos != new_payload && pos->vc_start_slot >
> > > > > > > > new_payload-
> > > > > > > > vc_start_slot)
> > > > > > > >                     pos->vc_start_slot -=
> > > > > > > > old_payload->time_slots; @@ -
> > > > > > > 3382,9 +3409,10
> > > > > > > > @@ void drm_dp_remove_payload(struct
> > drm_dp_mst_topology_mgr
> > > > > > > *mgr,
> > > > > > > >
> > > > > > > >     if (new_payload->delete)
> > > > > > > >             drm_dp_mst_put_port_malloc(new_payload->port);
> > > > > > > > -}
> > > > > > > > -EXPORT_SYMBOL(drm_dp_remove_payload);
> > > > > > > >
> > > > > > > > +   new_payload->payload_allocation_status =
> > > > > > > > +DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
> > > > > > > > +}
> > > > > > > > +EXPORT_SYMBOL(drm_dp_remove_payload_part2);
> > > > > > > >  /**
> > > > > > > >   * drm_dp_add_payload_part2() - Execute payload update part 2
> > > > > > > >   * @mgr: Manager to use.
> > > > > > > > @@ -3403,17 +3431,19 @@ int
> > drm_dp_add_payload_part2(struct
> > > > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > > > >     int ret = 0;
> > > > > > > >
> > > > > > > >     /* Skip failed payloads */
> > > > > > > > -   if (payload->vc_start_slot == -1) {
> > > > > > > > -           drm_dbg_kms(mgr->dev, "Part 1 of payload creation for %s
> > > > > > > failed, skipping part 2\n",
> > > > > > > > +   if (payload->payload_allocation_status !=
> > > > > > > DRM_DP_MST_PAYLOAD_ALLOCATION_DFP) {
> > > > > > > > +           drm_dbg_kms(state->dev, "Part 1 of payload
> > > > > > > > + creation for %s
> > > > > > > failed,
> > > > > > > > +skipping part 2\n",
> > > > > > > >                         payload->port->connector->name);
> > > > > > > >             return -EIO;
> > > > > > > >     }
> > > > > > > >
> > > > > > > > -   ret = drm_dp_create_payload_step2(mgr, payload);
> > > > > > > > -   if (ret < 0) {
> > > > > > > > +   /* Allocate payload to remote end */
> > > > > > > > +   ret = drm_dp_create_payload_to_remote(mgr, payload);
> > > > > > > > +   if (ret < 0)
> > > > > > > >             drm_err(mgr->dev, "Step 2 of creating MST
> > > > > > > > payload for %p
> > > > > > > failed: %d\n",
> > > > > > > >                     payload->port, ret);
> > > > > > > > -   }
> > > > > > > > +   else
> > > > > > > > +           payload->payload_allocation_status =
> > > > > > > > +DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE;
> > > > > > > >
> > > > > > > >     return ret;
> > > > > > > >  }
> > > > > > > > @@ -4324,6 +4354,7 @@ int
> > > > > > > > drm_dp_atomic_find_time_slots(struct
> > > > > > > drm_atomic_state *state,
> > > > > > > >             drm_dp_mst_get_port_malloc(port);
> > > > > > > >             payload->port = port;
> > > > > > > >             payload->vc_start_slot = -1;
> > > > > > > > +           payload->payload_allocation_status =
> > > > > > > > +DRM_DP_MST_PAYLOAD_ALLOCATION_NONE;
> > > > > > > >             list_add(&payload->next, &topology_state->payloads);
> > > > > > > >     }
> > > > > > > >     payload->time_slots = req_slots; @@ -4493,7 +4524,7 @@
> > > > > > > > void
> > > > > > > drm_dp_mst_atomic_wait_for_dependencies(struct
> > > > > > > drm_atomic_state
> > > > > > > *state)
> > > > > > > >             }
> > > > > > > >
> > > > > > > >             /* Now that previous state is committed, it's
> > > > > > > > safe to copy over
> > > > > > > the start slot
> > > > > > > > -            * assignments
> > > > > > > > +            * and allocation status assignments
> > > > > > > >              */
> > > > > > > >             list_for_each_entry(old_payload,
> > > > > > > > &old_mst_state->payloads,
> > > > > > > next) {
> > > > > > > >                     if (old_payload->delete) @@ -4502,6
> > > > > > > > +4533,8 @@ void
> > > > > > > drm_dp_mst_atomic_wait_for_dependencies(struct
> > > > > > > drm_atomic_state
> > > > > > > *state)
> > > > > > > >                     new_payload =
> > > > > > > drm_atomic_get_mst_payload_state(new_mst_state,
> > > > > > > >
> > > > > > > old_payload->port);
> > > > > > > >                     new_payload->vc_start_slot =
> > > > > > > > old_payload- vc_start_slot;
> > > > > > > > +                   new_payload->payload_allocation_status =
> > > > > > > > +
> > > > > > > > + old_payload-
> > > > > > > > payload_allocation_status;
> > > > > > >
> > > > > > > And here. Besides that, I think patches 1/3 and 2/3 look
> > > > > > > great! Just finished testing them on nouveau:
> > > > > > >
> > > > > > > Reviewed-by: Lyude Paul <lyude@redhat.com>
> > > > > > >
> > > > > > > Patch 3/3 I gotta think about a bit more (and am curious about
> > > > > > > Imre's current take on it) I think
> > > > > > >
> > > > > > > >             }
> > > > > > > >     }
> > > > > > > >  }
> > > > > > > > @@ -4818,6 +4851,13 @@ void
> > drm_dp_mst_dump_topology(struct
> > > > > > > seq_file *m,
> > > > > > > >     struct drm_dp_mst_atomic_payload *payload;
> > > > > > > >     int i, ret;
> > > > > > > >
> > > > > > > > +   static const char *const status[] = {
> > > > > > > > +           "None",
> > > > > > > > +           "Local",
> > > > > > > > +           "DFP",
> > > > > > > > +           "Remote",
> > > > > > > > +   };
> > > > > > > > +
> > > > > > > >     mutex_lock(&mgr->lock);
> > > > > > > >     if (mgr->mst_primary)
> > > > > > > >             drm_dp_mst_dump_mstb(m, mgr->mst_primary); @@ -
> > > > > > > 4834,7 +4874,7 @@
> > > > > > > > void drm_dp_mst_dump_topology(struct seq_file *m,
> > > > > > > >     seq_printf(m, "payload_mask: %x, max_payloads: %d, start_slot:
> > > > > > > > %u,
> > > > > > > pbn_div: %d\n",
> > > > > > > >                state->payload_mask, mgr->max_payloads,
> > > > > > > > state- start_slot,
> > > > > > > > state->pbn_div);
> > > > > > > >
> > > > > > > > -   seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc |     sink
> > name
> > > > > > > > \n");
> > > > > > > > +   seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc | status |
> > sink
> > > > > > > name     |\n");
> > > > > > > >     for (i = 0; i < mgr->max_payloads; i++) {
> > > > > > > >             list_for_each_entry(payload, &state->payloads, next) {
> > > > > > > >                     char name[14]; @@ -4843,7 +4883,7 @@
> > > > > > > > void drm_dp_mst_dump_topology(struct
> > > > > > > seq_file *m,
> > > > > > > >                             continue;
> > > > > > > >
> > > > > > > >                     fetch_monitor_name(mgr, payload->port,
> > > > > > > > name,
> > > > > > > sizeof(name));
> > > > > > > > -                   seq_printf(m, " %5d %6d %6d %02d - %02d %5d %5s
> > > > > > > %19s\n",
> > > > > > > > +                   seq_printf(m, " %5d %6d %6d %02d - %02d
> > > > > > > > + %5d %5s
> > > > > > > %8s %19s\n",
> > > > > > > >                                i,
> > > > > > > >                                payload->port->port_num,
> > > > > > > >                                payload->vcpi, @@ -4851,6
> > > > > > > > +4891,7 @@ void drm_dp_mst_dump_topology(struct
> > > > > > > seq_file *m,
> > > > > > > >                                payload->vc_start_slot +
> > > > > > > > payload- time_slots - 1,
> > > > > > > >                                payload->pbn,
> > > > > > > >                                payload->dsc_enabled ? "Y" :
> > > > > > > > "N",
> > > > > > > > +
> > > > > > > > + status[payload->payload_allocation_status],
> > > > > > > >                                (*name != 0) ? name : "Unknown");
> > > > > > > >             }
> > > > > > > >     }
> > > > > > > > diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > > > > > > b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > > > > > > index e3f176a093d2..5f73cdabe7a1 100644
> > > > > > > > --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > > > > > > +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > > > > > > > @@ -557,12 +557,8 @@ static void intel_mst_disable_dp(struct
> > > > > > > intel_atomic_state *state,
> > > > > > > >     struct intel_dp *intel_dp = &dig_port->dp;
> > > > > > > >     struct intel_connector *connector =
> > > > > > > >             to_intel_connector(old_conn_state->connector);
> > > > > > > > -   struct drm_dp_mst_topology_state *old_mst_state =
> > > > > > > > -           drm_atomic_get_old_mst_topology_state(&state->base,
> > > > > > > &intel_dp->mst_mgr);
> > > > > > > >     struct drm_dp_mst_topology_state *new_mst_state =
> > > > > > > >
> > > > > > > > drm_atomic_get_new_mst_topology_state(&state->base,
> > > > > > > &intel_dp->mst_mgr);
> > > > > > > > -   const struct drm_dp_mst_atomic_payload *old_payload =
> > > > > > > > -           drm_atomic_get_mst_payload_state(old_mst_state,
> > > > > > > connector->port);
> > > > > > > >     struct drm_dp_mst_atomic_payload *new_payload =
> > > > > > > >             drm_atomic_get_mst_payload_state(new_mst_state,
> > > > > > > connector->port);
> > > > > > > >     struct drm_i915_private *i915 =
> > > > > > > > to_i915(connector->base.dev); @@
> > > > > > > > -572,8 +568,7 @@ static void intel_mst_disable_dp(struct
> > > > > > > > intel_atomic_state *state,
> > > > > > > >
> > > > > > > >     intel_hdcp_disable(intel_mst->connector);
> > > > > > > >
> > > > > > > > -   drm_dp_remove_payload(&intel_dp->mst_mgr, new_mst_state,
> > > > > > > > -                         old_payload, new_payload);
> > > > > > > > +   drm_dp_remove_payload_part1(&intel_dp->mst_mgr,
> > > > > > > new_mst_state,
> > > > > > > > +new_payload);
> > > > > > > >
> > > > > > > >     intel_audio_codec_disable(encoder, old_crtc_state,
> > > > > > > > old_conn_state); } @@ -588,6 +583,14 @@ static void
> > > > > > > > intel_mst_post_disable_dp(struct intel_atomic_state *state,
> > > > > > > >     struct intel_dp *intel_dp = &dig_port->dp;
> > > > > > > >     struct intel_connector *connector =
> > > > > > > >             to_intel_connector(old_conn_state->connector);
> > > > > > > > +   struct drm_dp_mst_topology_state *old_mst_state =
> > > > > > > > +
> > > > > > > > + drm_atomic_get_old_mst_topology_state(&state->base,
> > > > > > > &intel_dp->mst_mgr);
> > > > > > > > +   struct drm_dp_mst_topology_state *new_mst_state =
> > > > > > > > +
> > > > > > > > + drm_atomic_get_new_mst_topology_state(&state->base,
> > > > > > > &intel_dp->mst_mgr);
> > > > > > > > +   const struct drm_dp_mst_atomic_payload *old_payload =
> > > > > > > > +           drm_atomic_get_mst_payload_state(old_mst_state,
> > > > > > > connector->port);
> > > > > > > > +   struct drm_dp_mst_atomic_payload *new_payload =
> > > > > > > > +           drm_atomic_get_mst_payload_state(new_mst_state,
> > > > > > > connector->port);
> > > > > > > >     struct drm_i915_private *dev_priv = to_i915(connector-
> > >base.dev);
> > > > > > > >     bool last_mst_stream;
> > > > > > > >
> > > > > > > > @@ -608,6 +611,9 @@ static void
> > > > > > > > intel_mst_post_disable_dp(struct intel_atomic_state *state,
> > > > > > > >
> > > > > > > >     wait_for_act_sent(encoder, old_crtc_state);
> > > > > > > >
> > > > > > > > +   drm_dp_remove_payload_part2(&intel_dp->mst_mgr,
> > > > > > > new_mst_state,
> > > > > > > > +                               old_payload, new_payload);
> > > > > > > > +
> > > > > > > >     intel_ddi_disable_transcoder_func(old_crtc_state);
> > > > > > > >
> > > > > > > >     if (DISPLAY_VER(dev_priv) >= 9) diff --git
> > > > > > > > a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > > > > > > b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > > > > > > index 4e7c9c353c51..bba01fa0780c 100644
> > > > > > > > --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > > > > > > +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > > > > > > @@ -882,21 +882,26 @@ struct nouveau_encoder
> > > > > > > > *nv50_real_outp(struct drm_encoder *encoder)
> > > > > > > >
> > > > > > > >  static void
> > > > > > > >  nv50_msto_cleanup(struct drm_atomic_state *state,
> > > > > > > > -             struct drm_dp_mst_topology_state *mst_state,
> > > > > > > > +             struct drm_dp_mst_topology_state
> > > > > > > > + *new_mst_state,
> > > > > > > >               struct drm_dp_mst_topology_mgr *mgr,
> > > > > > > >               struct nv50_msto *msto)  {
> > > > > > > >     struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
> > > > > > > > -   struct drm_dp_mst_atomic_payload *payload =
> > > > > > > > -           drm_atomic_get_mst_payload_state(mst_state, msto->mstc-
> > > > > > > > port);
> > > > > > > > +   struct drm_dp_mst_atomic_payload *new_payload =
> > > > > > > > +           drm_atomic_get_mst_payload_state(new_mst_state,
> > > > > > > > + msto-
> > > > > > > > mstc->port);
> > > > > > > > +   struct drm_dp_mst_topology_state *old_mst_state =
> > > > > > > > +           drm_atomic_get_old_mst_topology_state(state, mgr);
> > > > > > > > +   const struct drm_dp_mst_atomic_payload *old_payload =
> > > > > > > > +           drm_atomic_get_mst_payload_state(old_mst_state,
> > > > > > > > + msto-
> > > > > > > > mstc->port);
> > > > > > > >
> > > > > > > >     NV_ATOMIC(drm, "%s: msto cleanup\n",
> > > > > > > > msto->encoder.name);
> > > > > > > >
> > > > > > > >     if (msto->disabled) {
> > > > > > > >             msto->mstc = NULL;
> > > > > > > >             msto->disabled = false;
> > > > > > > > +           drm_dp_remove_payload_part2(mgr, new_mst_state,
> > > > > > > old_payload,
> > > > > > > > +new_payload);
> > > > > > > >     } else if (msto->enabled) {
> > > > > > > > -           drm_dp_add_payload_part2(mgr, state, payload);
> > > > > > > > +           drm_dp_add_payload_part2(mgr, state,
> > > > > > > > + new_payload);
> > > > > > > >             msto->enabled = false;
> > > > > > > >     }
> > > > > > > >  }
> > > > > > > > @@ -910,19 +915,15 @@ nv50_msto_prepare(struct
> > > > > > > > drm_atomic_state
> > > > > > > *state,
> > > > > > > >     struct nouveau_drm *drm = nouveau_drm(msto->encoder.dev);
> > > > > > > >     struct nv50_mstc *mstc = msto->mstc;
> > > > > > > >     struct nv50_mstm *mstm = mstc->mstm;
> > > > > > > > -   struct drm_dp_mst_topology_state *old_mst_state;
> > > > > > > > -   struct drm_dp_mst_atomic_payload *payload, *old_payload;
> > > > > > > > +   struct drm_dp_mst_atomic_payload *payload;
> > > > > > > >
> > > > > > > >     NV_ATOMIC(drm, "%s: msto prepare\n",
> > > > > > > > msto->encoder.name);
> > > > > > > >
> > > > > > > > -   old_mst_state = drm_atomic_get_old_mst_topology_state(state,
> > > > > > > mgr);
> > > > > > > > -
> > > > > > > >     payload = drm_atomic_get_mst_payload_state(mst_state,
> > > > > > > > mstc- port);
> > > > > > > > -   old_payload =
> > drm_atomic_get_mst_payload_state(old_mst_state,
> > > > > > > mstc->port);
> > > > > > > >
> > > > > > > >     // TODO: Figure out if we want to do a better job of
> > > > > > > > handling VCPI
> > > > > > > allocation failures here?
> > > > > > > >     if (msto->disabled) {
> > > > > > > > -           drm_dp_remove_payload(mgr, mst_state, old_payload,
> > > > > > > payload);
> > > > > > > > +           drm_dp_remove_payload_part1(mgr, mst_state,
> > > > > > > > + payload);
> > > > > > > >
> > > > > > > >             nvif_outp_dp_mst_vcpi(&mstm->outp->outp,
> > > > > > > > msto->head- base.index, 0, 0, 0, 0);
> > > > > > > >     } else {
> > > > > > > > diff --git a/include/drm/display/drm_dp_mst_helper.h
> > > > > > > > b/include/drm/display/drm_dp_mst_helper.h
> > > > > > > > index ed5c9660563c..4429d3b1745b 100644
> > > > > > > > --- a/include/drm/display/drm_dp_mst_helper.h
> > > > > > > > +++ b/include/drm/display/drm_dp_mst_helper.h
> > > > > > > > @@ -46,6 +46,13 @@ struct drm_dp_mst_topology_ref_history {
> > > > > > > > }; #endif /*
> > > > > IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) */
> > > > > > > >
> > > > > > > > +enum drm_dp_mst_payload_allocation {
> > > > > > > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_NONE,
> > > > > > > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_LOCAL,
> > > > > > > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_DFP,
> > > > > > > > +   DRM_DP_MST_PAYLOAD_ALLOCATION_REMOTE,
> > > > > > > > +};
> > > > > > > > +
> > > > > > > >  struct drm_dp_mst_branch;
> > > > > > > >
> > > > > > > >  /**
> > > > > > > > @@ -537,7 +544,7 @@ struct drm_dp_mst_atomic_payload {
> > > > > > > >      *   drm_dp_mst_atomic_wait_for_dependencies() has been
> > called,
> > > > > > > which will ensure the
> > > > > > > >      *   previous MST states payload start slots have been copied over
> > to
> > > > > > > the new state. Note
> > > > > > > >      *   that a new start slot won't be assigned/removed from this
> > payload
> > > > > > > until
> > > > > > > > -    *   drm_dp_add_payload_part1()/drm_dp_remove_payload()
> > have
> > > > > > > been called.
> > > > > > > > +    *
> > drm_dp_add_payload_part1()/drm_dp_remove_payload_part2()
> > > > > > > have been called.
> > > > > > > >      * * Acquire the MST modesetting lock, and then wait for
> > > > > > > > any pending
> > > > > > > MST-related commits to
> > > > > > > >      *   get committed to hardware by calling drm_crtc_commit_wait()
> > on
> > > > > > > each of the
> > > > > > > >      *   &drm_crtc_commit structs in
> > > > > > > &drm_dp_mst_topology_state.commit_deps.
> > > > > > > > @@ -564,6 +571,9 @@ struct drm_dp_mst_atomic_payload {
> > > > > > > >     /** @dsc_enabled: Whether or not this payload has DSC enabled
> > */
> > > > > > > >     bool dsc_enabled : 1;
> > > > > > > >
> > > > > > > > +   /** @payload_allocation_status: The allocation status of
> > > > > > > > + this payload
> > > > > > > */
> > > > > > > > +   enum drm_dp_mst_payload_allocation
> > > > > > > > + payload_allocation_status;
> > > > > > > > +
> > > > > > > >     /** @next: The list node for this payload */
> > > > > > > >     struct list_head next;
> > > > > > > >  };
> > > > > > > > @@ -842,10 +852,13 @@ int drm_dp_add_payload_part1(struct
> > > > > > > > drm_dp_mst_topology_mgr *mgr,  int
> > > > > drm_dp_add_payload_part2(struct
> > > > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > > > >                          struct drm_atomic_state *state,
> > > > > > > >                          struct drm_dp_mst_atomic_payload
> > > > > > > > *payload); -
> > > > > > > void
> > > > > > > > drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
> > > > > > > > -                      struct drm_dp_mst_topology_state *mst_state,
> > > > > > > > -                      const struct drm_dp_mst_atomic_payload
> > > > > > > *old_payload,
> > > > > > > > -                      struct drm_dp_mst_atomic_payload
> > > > > > > *new_payload);
> > > > > > > > +void drm_dp_remove_payload_part1(struct
> > > > > drm_dp_mst_topology_mgr
> > > > > > > *mgr,
> > > > > > > > +                            struct
> > > > > > > > + drm_dp_mst_topology_state
> > > > > > > *mst_state,
> > > > > > > > +                            struct
> > > > > > > > + drm_dp_mst_atomic_payload
> > > > > > > *payload); void
> > > > > > > > +drm_dp_remove_payload_part2(struct
> > drm_dp_mst_topology_mgr
> > > > > *mgr,
> > > > > > > > +                            struct
> > > > > > > > + drm_dp_mst_topology_state
> > > > > > > *mst_state,
> > > > > > > > +                            const struct
> > > > > > > > + drm_dp_mst_atomic_payload
> > > > > > > *old_payload,
> > > > > > > > +                            struct
> > > > > > > > + drm_dp_mst_atomic_payload
> > > > > > > *new_payload);
> > > > > > > >
> > > > > > > >  int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr
> > > > > > > > *mgr);
> > > > > > > >
> > > > > > >
> > > > > > > --
> > > > > > > Cheers,
> > > > > > >  Lyude Paul (she/her)
> > > > > > >  Software Engineer at Red Hat
> > > > > > --
> > > > > > Regards,
> > > > > > Wayne
> > > > >
> > > > > --
> > > > > Cheers,
> > > > >  Lyude Paul (she/her)
> > > > >  Software Engineer at Red Hat
> > > > --
> > > > Regards,
> > > > Wayne
> > > >
> > >
> > > --
> > > Cheers,
> > >  Lyude Paul (she/her)
> > >  Software Engineer at Red Hat
> > >