[PATCH v10 0/6] MHDP8546 fixes related to DRM_BRIDGE_ATTACH_NO_CONNECTOR usecase

[PATCH v10 0/6] MHDP8546 fixes related to DRM_BRIDGE_ATTACH_NO_CONNECTOR usecase

[Harikrishna Shenoy]

With the DRM_BRIDGE_ATTACH_NO_CONNECTOR framework, the connector is 
no longer initialized in  bridge_attach() when the display controller 
sets the DRM_BRIDGE_ATTACH_NO_CONNECTOR flag. 
This causes a null pointer dereference in cdns_mhdp_modeset_retry_fn() 
when trying to access &conn->dev->mode_config.mutex. 
Observed on a board where EDID read failed. 
(log: https://gist.github.com/Jayesh2000/233f87f9becdf1e66f1da6fd53f77429)

Patch 1 adds a connector_ptr which takes care of both 
DRM_BRIDGE_ATTACH_NO_CONNECTOR and !DRM_BRIDGE_ATTACH_NO_CONNECTOR 
case by setting the pointer in appropriate hooks and checking for pointer 
validity before accessing the connector.
Patch 2 adds mode validation hook to bridge fucntions.
Patch 3 fixes HDCP to work with both DRM_BRIDGE_ATTACH_NO_CONNECTOR 
and !DRM_BRIDGE_ATTACH_NO_CONNECTOR case by moving HDCP state handling 
into the bridge atomic check inline with the 
DRM_BRIDGE_ATTACH_NO_CONNECTOR model.
Patches 4,5 do necessary cleanup and alignment for using
connector pointer.

The rationale behind the sequence of commits is we can cleanly 
switch to drm_connector pointer after removal of connector helper 
code blocks, which are anyways not touch after 
DRM_BRIDGE_ATTACH_NO_CONNECTOR has been enabled in driver.

The last patch make smaller adjustment: lowering the log level for
noisy DPCD transfer errors.


v9 patch link: 
<https://lore.kernel.org/all/20251120121416.660781-1-h-shenoy@ti.com/>

Changelog v9-v10:
-Rebased on drm-misc-next.
-Removed redundant checks on connector_ptr in Patch 1 as pointed out in 
<https://lore.kernel.org/all/9a041a93-c004-40a9-b94e-ae3fce339145@ideasonboard.com/>
<https://lore.kernel.org/all/6a696e33-b855-4fc7-8325-304a009ed001@ideasonboard.com/>
-Update commit message for patch 2,3,4,5 addresing
<https://lore.kernel.org/all/8c97c5e9-7705-4368-a3a9-45e209582c3f@ideasonboard.com/>
<https://lore.kernel.org/all/b6e44d61-7704-48fa-ba03-ba1a75e8a4f8@ideasonboard.com/>
<https://lore.kernel.org/all/add3532c-610f-4d41-92e1-1f440495f1d2@ideasonboard.com/>
<https://lore.kernel.org/all/082379e2-2d00-4f2f-82dd-cff93d2867af@ideasonboard.com/>

v8 patch link:
<https://lore.kernel.org/all/20251014094527.3916421-1-h-shenoy@ti.com/>

Changelog v8-v9:
-Move the patch 6 in v8 related to HDCP to patch 3 and add fixes tag.
-Update to connector_ptr in HDCP code in patch 1.
-Rebased on next-20251114.

v7 patch link:
<https://lore.kernel.org/all/20250929083936.1575685-1-h-shenoy@ti.com/>

Changelog v7-v8:
-Move patches with firxes tag to top of series with appropriate changes
to them.
-Add R/B tag to patch 
https://lore.kernel.org/all/ae3snoap64r252sbqhsshsadxfmlqdfn6b4o5fgfcmxppglkqf@2lsstfsghzwb/

v6 patch link:
<https://lore.kernel.org/all/20250909090824.1655537-1-h-shenoy@ti.com/>

Changelog v6-v7:
-Update cover letter to explain the series.
-Add R/B tag in PATCH 1 and drop fixes tag as suggested.
-Drop fixes tag in PATCH 2.
-Update the commit messages for clear understanding of changes done in patches.

v5 patch link:
<https://lore.kernel.org/all/20250811075904.1613519-1-h-shenoy@ti.com/>

Changelog v5 -> v6:
-Update cover letter to clarify the series in better way.
-Add Reviewed-by tag to relevant patches.
 
v4 patch link: 
<https://lore.kernel.org/all/20250624054448.192801-1-j-choudhary@ti.com>

Changelog v4->v5:
- Handle HDCP state in bridge atomic check instead of connector 
atomic check
 
v3 patch link:
<https://lore.kernel.org/all/20250529142517.188786-1-j-choudhary@ti.com/>

Changelog v3->v4:
- Fix kernel test robot build warning:
  <https://lore.kernel.org/all/202505300201.2s6r12yc-lkp@intel.com/>

v2 patch link:
<https://lore.kernel.org/all/20250521073237.366463-1-j-choudhary@ti.com/>

Changelog v2->v3:
- Add mode_valid in drm_bridge_funcs to a separate patch
- Remove "if (mhdp->connector.dev)" conditions that were missed in v2
- Split out the move of drm_atomic_get_new_connector_for_encoder()
  to a separate patch
- Drop "R-by" considering the changes in v2[1/3]
- Add Fixes tag to first 4 patches:
  commit c932ced6b585 ("drm/tidss: Update encoder/bridge chain connect model")
  This added DBANC flag in tidss while attaching bridge to the encoder
- Drop RFC prefix

v1 patch link:
<https://lore.kernel.org/all/20250116111636.157641-1-j-choudhary@ti.com/>

Changelog v1->v2:
- Remove !DRM_BRIDGE_ATTACH_NO_CONNECTOR entirely
- Add mode_valid in drm_bridge_funcs[0]
- Fix NULL POINTER differently since we cannot access atomic_state
- Reduce log level in cdns_mhdp_transfer call


Harikrishna Shenoy (1):
  drm/bridge: cadence: cdns-mhdp8546-core: Handle HDCP state in bridge
    atomic check

Jayesh Choudhary (5):
  drm/bridge: cadence: cdns-mhdp8546-core: Set the mhdp connector
    earlier in atomic_enable()
  drm/bridge: cadence: cdns-mhdp8546-core: Add mode_valid hook to
    drm_bridge_funcs
  drm/bridge: cadence: cdns-mhdp8546-core: Remove legacy support for
    connector initialisation in bridge
  cadence: cdns-mhdp8546*: Change drm_connector from structure to
    pointer
  drm/bridge: cadence: cdns-mhdp8546-core: Reduce log level for DPCD
    read/write

 .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 257 +++++-------------
 .../drm/bridge/cadence/cdns-mhdp8546-core.h   |   2 +-
 .../drm/bridge/cadence/cdns-mhdp8546-hdcp.c   |  18 +-
 3 files changed, 81 insertions(+), 196 deletions(-)

-- 
2.34.1

[PATCH v10 1/6] drm/bridge: cadence: cdns-mhdp8546-core: Set the mhdp connector earlier in atomic_enable()

[Harikrishna Shenoy]

From: Jayesh Choudhary <j-choudhary@ti.com>

In case if we get errors in cdns_mhdp_link_up() or cdns_mhdp_reg_read()
in atomic_enable, we will go to cdns_mhdp_modeset_retry_fn() and will hit
NULL pointer while trying to access the mutex. We need the connector to
be set before that. Unlike in legacy cases with flag
!DRM_BRIDGE_ATTACH_NO_CONNECTOR, we do not have connector initialised
in bridge_attach(), so add the mhdp->connector_ptr in device structure
to handle both cases with DRM_BRIDGE_ATTACH_NO_CONNECTOR and
!DRM_BRIDGE_ATTACH_NO_CONNECTOR, set it in atomic_enable() earlier to
avoid possible NULL pointer dereference in recovery paths like
modeset_retry_fn() with the DRM_BRIDGE_ATTACH_NO_CONNECTOR flag set.

Fixes: c932ced6b585 ("drm/tidss: Update encoder/bridge chain connect model")
Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>
---
 .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 29 ++++++++++---------
 .../drm/bridge/cadence/cdns-mhdp8546-core.h   |  1 +
 .../drm/bridge/cadence/cdns-mhdp8546-hdcp.c   | 18 +++++++++---
 3 files changed, 30 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
index 38726ae1bf150..ef2d0ea606f78 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -740,7 +740,7 @@ static void cdns_mhdp_fw_cb(const struct firmware *fw, void *context)
 	bridge_attached = mhdp->bridge_attached;
 	spin_unlock(&mhdp->start_lock);
 	if (bridge_attached) {
-		if (mhdp->connector.dev)
+		if (mhdp->connector_ptr)
 			drm_kms_helper_hotplug_event(mhdp->bridge.dev);
 		else
 			drm_bridge_hpd_notify(&mhdp->bridge, cdns_mhdp_detect(mhdp));
@@ -1636,6 +1636,7 @@ static int cdns_mhdp_connector_init(struct cdns_mhdp_device *mhdp)
 		return ret;
 	}
 
+	mhdp->connector_ptr = conn;
 	drm_connector_helper_add(conn, &cdns_mhdp_conn_helper_funcs);
 
 	ret = drm_display_info_set_bus_formats(&conn->display_info,
@@ -1915,17 +1916,25 @@ static void cdns_mhdp_atomic_enable(struct drm_bridge *bridge,
 	struct cdns_mhdp_device *mhdp = bridge_to_mhdp(bridge);
 	struct cdns_mhdp_bridge_state *mhdp_state;
 	struct drm_crtc_state *crtc_state;
-	struct drm_connector *connector;
 	struct drm_connector_state *conn_state;
 	struct drm_bridge_state *new_state;
 	const struct drm_display_mode *mode;
 	u32 resp;
-	int ret;
+	int ret = 0;
 
 	dev_dbg(mhdp->dev, "bridge enable\n");
 
 	mutex_lock(&mhdp->link_mutex);
 
+	mhdp->connector_ptr = drm_atomic_get_new_connector_for_encoder(state,
+								       bridge->encoder);
+	if (WARN_ON(!mhdp->connector_ptr))
+		goto out;
+
+	conn_state = drm_atomic_get_new_connector_state(state, mhdp->connector_ptr);
+	if (WARN_ON(!conn_state))
+		goto out;
+
 	if (mhdp->plugged && !mhdp->link_up) {
 		ret = cdns_mhdp_link_up(mhdp);
 		if (ret < 0)
@@ -1945,15 +1954,6 @@ static void cdns_mhdp_atomic_enable(struct drm_bridge *bridge,
 	cdns_mhdp_reg_write(mhdp, CDNS_DPTX_CAR,
 			    resp | CDNS_VIF_CLK_EN | CDNS_VIF_CLK_RSTN);
 
-	connector = drm_atomic_get_new_connector_for_encoder(state,
-							     bridge->encoder);
-	if (WARN_ON(!connector))
-		goto out;
-
-	conn_state = drm_atomic_get_new_connector_state(state, connector);
-	if (WARN_ON(!conn_state))
-		goto out;
-
 	if (mhdp->hdcp_supported &&
 	    mhdp->hw_state == MHDP_HW_READY &&
 	    conn_state->content_protection ==
@@ -2030,6 +2030,7 @@ static void cdns_mhdp_atomic_disable(struct drm_bridge *bridge,
 	if (mhdp->info && mhdp->info->ops && mhdp->info->ops->disable)
 		mhdp->info->ops->disable(mhdp);
 
+	mhdp->connector_ptr = NULL;
 	mutex_unlock(&mhdp->link_mutex);
 }
 
@@ -2296,7 +2297,7 @@ static void cdns_mhdp_modeset_retry_fn(struct work_struct *work)
 
 	mhdp = container_of(work, typeof(*mhdp), modeset_retry_work);
 
-	conn = &mhdp->connector;
+	conn = mhdp->connector_ptr;
 
 	/* Grab the locks before changing connector property */
 	mutex_lock(&conn->dev->mode_config.mutex);
@@ -2373,7 +2374,7 @@ static void cdns_mhdp_hpd_work(struct work_struct *work)
 	int ret;
 
 	ret = cdns_mhdp_update_link_status(mhdp);
-	if (mhdp->connector.dev) {
+	if (mhdp->connector_ptr) {
 		if (ret < 0)
 			schedule_work(&mhdp->modeset_retry_work);
 		else
diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
index bad2fc0c73066..a76775c768956 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
@@ -376,6 +376,7 @@ struct cdns_mhdp_device {
 	struct mutex link_mutex;
 
 	struct drm_connector connector;
+	struct drm_connector *connector_ptr;
 	struct drm_bridge bridge;
 
 	struct cdns_mhdp_link link;
diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c
index 42248f179b69d..21a7d2fb266e4 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c
@@ -394,7 +394,7 @@ static int _cdns_mhdp_hdcp_disable(struct cdns_mhdp_device *mhdp)
 	int ret;
 
 	dev_dbg(mhdp->dev, "[%s:%d] HDCP is being disabled...\n",
-		mhdp->connector.name, mhdp->connector.base.id);
+		mhdp->connector_ptr->name, mhdp->connector_ptr->base.id);
 
 	ret = cdns_mhdp_hdcp_set_config(mhdp, 0, false);
 
@@ -436,6 +436,10 @@ static int cdns_mhdp_hdcp_check_link(struct cdns_mhdp_device *mhdp)
 	int ret = 0;
 
 	mutex_lock(&mhdp->hdcp.mutex);
+
+	if (!mhdp->connector_ptr)
+		goto out;
+
 	if (mhdp->hdcp.value == DRM_MODE_CONTENT_PROTECTION_UNDESIRED)
 		goto out;
 
@@ -445,7 +449,7 @@ static int cdns_mhdp_hdcp_check_link(struct cdns_mhdp_device *mhdp)
 
 	dev_err(mhdp->dev,
 		"[%s:%d] HDCP link failed, retrying authentication\n",
-		mhdp->connector.name, mhdp->connector.base.id);
+		mhdp->connector_ptr->name, mhdp->connector_ptr->base.id);
 
 	ret = _cdns_mhdp_hdcp_disable(mhdp);
 	if (ret) {
@@ -487,13 +491,19 @@ static void cdns_mhdp_hdcp_prop_work(struct work_struct *work)
 	struct cdns_mhdp_device *mhdp = container_of(hdcp,
 						     struct cdns_mhdp_device,
 						     hdcp);
-	struct drm_device *dev = mhdp->connector.dev;
+	struct drm_device *dev = NULL;
 	struct drm_connector_state *state;
 
+	if (mhdp->connector_ptr)
+		dev = mhdp->connector_ptr->dev;
+
+	if (!dev)
+		return;
+
 	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
 	mutex_lock(&mhdp->hdcp.mutex);
 	if (mhdp->hdcp.value != DRM_MODE_CONTENT_PROTECTION_UNDESIRED) {
-		state = mhdp->connector.state;
+		state = mhdp->connector_ptr->state;
 		state->content_protection = mhdp->hdcp.value;
 	}
 	mutex_unlock(&mhdp->hdcp.mutex);
-- 
2.34.1

[PATCH v10 2/6] drm/bridge: cadence: cdns-mhdp8546-core: Add mode_valid hook to drm_bridge_funcs

[Harikrishna Shenoy]

From: Jayesh Choudhary <j-choudhary@ti.com>

Add cdns_mhdp_bridge_mode_valid() to check if specific mode is valid for
this bridge or not. In the legacy usecase with
!DRM_BRIDGE_ATTACH_NO_CONNECTOR we were using the hook from
drm_connector_helper_funcs but with DRM_BRIDGE_ATTACH_NO_CONNECTOR
we need to have mode_valid() in drm_bridge_funcs.

Without this patch, when using DRM_BRIDGE_ATTACH_NO_CONNECTOR
flag, the cdns_mhdp_bandwidth_ok() function would not be called
during  mode validation, potentially allowing modes that exceed
the bridge's bandwidth capabilities to be incorrectly marked as
valid.

Fixes: c932ced6b585 ("drm/tidss: Update encoder/bridge chain connect model")
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>
---
 .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
index ef2d0ea606f78..2fb8acd363b14 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -2162,6 +2162,25 @@ static const struct drm_edid *cdns_mhdp_bridge_edid_read(struct drm_bridge *brid
 	return cdns_mhdp_edid_read(mhdp, connector);
 }
 
+static enum drm_mode_status
+cdns_mhdp_bridge_mode_valid(struct drm_bridge *bridge,
+			    const struct drm_display_info *info,
+			    const struct drm_display_mode *mode)
+{
+	struct cdns_mhdp_device *mhdp = bridge_to_mhdp(bridge);
+
+	mutex_lock(&mhdp->link_mutex);
+
+	if (!cdns_mhdp_bandwidth_ok(mhdp, mode, mhdp->link.num_lanes,
+				    mhdp->link.rate)) {
+		mutex_unlock(&mhdp->link_mutex);
+		return MODE_CLOCK_HIGH;
+	}
+
+	mutex_unlock(&mhdp->link_mutex);
+	return MODE_OK;
+}
+
 static const struct drm_bridge_funcs cdns_mhdp_bridge_funcs = {
 	.atomic_enable = cdns_mhdp_atomic_enable,
 	.atomic_disable = cdns_mhdp_atomic_disable,
@@ -2176,6 +2195,7 @@ static const struct drm_bridge_funcs cdns_mhdp_bridge_funcs = {
 	.edid_read = cdns_mhdp_bridge_edid_read,
 	.hpd_enable = cdns_mhdp_bridge_hpd_enable,
 	.hpd_disable = cdns_mhdp_bridge_hpd_disable,
+	.mode_valid = cdns_mhdp_bridge_mode_valid,
 };
 
 static bool cdns_mhdp_detect_hpd(struct cdns_mhdp_device *mhdp, bool *hpd_pulse)
-- 
2.34.1

[PATCH v10 3/6] drm/bridge: cadence: cdns-mhdp8546-core: Handle HDCP state in bridge atomic check

[Harikrishna Shenoy]

Now that we have DRM_BRIDGE_ATTACH_NO_CONNECTOR framework, handle the
HDCP state change in bridge atomic check as well to enable correct
functioning for HDCP in both DRM_BRIDGE_ATTACH_NO_CONNECTOR and
!DRM_BRIDGE_ATTACH_NO_CONNECTOR case.

Without this patch, when using DRM_BRIDGE_ATTACH_NO_CONNECTOR flag, HDCP
state changes would not be properly handled during atomic commits,
potentially leading to HDCP authentication failures or incorrect
protection status for content requiring HDCP encryption.

Fixes: 6a3608eae6d33 ("drm: bridge: cdns-mhdp8546: Enable HDCP")
Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>
---
 .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 23 +++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
index 2fb8acd363b14..7ee19b7cc92fc 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -2123,6 +2123,10 @@ static int cdns_mhdp_atomic_check(struct drm_bridge *bridge,
 {
 	struct cdns_mhdp_device *mhdp = bridge_to_mhdp(bridge);
 	const struct drm_display_mode *mode = &crtc_state->adjusted_mode;
+	struct drm_connector_state *old_state, *new_state;
+	struct drm_atomic_state *state = crtc_state->state;
+	struct drm_connector *conn = mhdp->connector_ptr;
+	u64 old_cp, new_cp;
 
 	mutex_lock(&mhdp->link_mutex);
 
@@ -2142,6 +2146,25 @@ static int cdns_mhdp_atomic_check(struct drm_bridge *bridge,
 	if (mhdp->info)
 		bridge_state->input_bus_cfg.flags = *mhdp->info->input_bus_flags;
 
+	if (conn && mhdp->hdcp_supported) {
+		old_state = drm_atomic_get_old_connector_state(state, conn);
+		new_state = drm_atomic_get_new_connector_state(state, conn);
+		old_cp = old_state->content_protection;
+		new_cp = new_state->content_protection;
+
+		if (old_state->hdcp_content_type != new_state->hdcp_content_type &&
+		    new_cp != DRM_MODE_CONTENT_PROTECTION_UNDESIRED) {
+			new_state->content_protection = DRM_MODE_CONTENT_PROTECTION_DESIRED;
+			crtc_state = drm_atomic_get_new_crtc_state(state, new_state->crtc);
+			crtc_state->mode_changed = true;
+		}
+
+		if (!new_state->crtc) {
+			if (old_cp == DRM_MODE_CONTENT_PROTECTION_ENABLED)
+				new_state->content_protection = DRM_MODE_CONTENT_PROTECTION_DESIRED;
+		}
+	}
+
 	mutex_unlock(&mhdp->link_mutex);
 	return 0;
 }
-- 
2.34.1

[PATCH v10 4/6] drm/bridge: cadence: cdns-mhdp8546-core: Remove legacy support for connector initialisation in bridge

[Harikrishna Shenoy]

From: Jayesh Choudhary <j-choudhary@ti.com>

Now that this bridge supports DRM_BRIDGE_ATTACH_NO_CONNECTOR,
and only TI K3 platforms consume this driver and
tidss (their display controller) has DRM_BRIDGE_ATTACH_NO_CONNECTOR
flag set,we can remove the legacy code for the
non-DRM_BRIDGE_ATTACH_NO_CONNECTOR case.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>
---
 .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 187 +-----------------
 1 file changed, 9 insertions(+), 178 deletions(-)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
index 7ee19b7cc92fc..e3066dae340a6 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -739,12 +739,8 @@ static void cdns_mhdp_fw_cb(const struct firmware *fw, void *context)
 	spin_lock(&mhdp->start_lock);
 	bridge_attached = mhdp->bridge_attached;
 	spin_unlock(&mhdp->start_lock);
-	if (bridge_attached) {
-		if (mhdp->connector_ptr)
-			drm_kms_helper_hotplug_event(mhdp->bridge.dev);
-		else
-			drm_bridge_hpd_notify(&mhdp->bridge, cdns_mhdp_detect(mhdp));
-	}
+	if (bridge_attached)
+		drm_bridge_hpd_notify(&mhdp->bridge, cdns_mhdp_detect(mhdp));
 }
 
 static int cdns_mhdp_load_firmware(struct cdns_mhdp_device *mhdp)
@@ -1444,56 +1440,6 @@ static const struct drm_edid *cdns_mhdp_edid_read(struct cdns_mhdp_device *mhdp,
 	return drm_edid_read_custom(connector, cdns_mhdp_get_edid_block, mhdp);
 }
 
-static int cdns_mhdp_get_modes(struct drm_connector *connector)
-{
-	struct cdns_mhdp_device *mhdp = connector_to_mhdp(connector);
-	const struct drm_edid *drm_edid;
-	int num_modes;
-
-	if (!mhdp->plugged)
-		return 0;
-
-	drm_edid = cdns_mhdp_edid_read(mhdp, connector);
-
-	drm_edid_connector_update(connector, drm_edid);
-
-	if (!drm_edid) {
-		dev_err(mhdp->dev, "Failed to read EDID\n");
-		return 0;
-	}
-
-	num_modes = drm_edid_connector_add_modes(connector);
-	drm_edid_free(drm_edid);
-
-	/*
-	 * HACK: Warn about unsupported display formats until we deal
-	 *       with them correctly.
-	 */
-	if (connector->display_info.color_formats &&
-	    !(connector->display_info.color_formats &
-	      mhdp->display_fmt.color_format))
-		dev_warn(mhdp->dev,
-			 "%s: No supported color_format found (0x%08x)\n",
-			__func__, connector->display_info.color_formats);
-
-	if (connector->display_info.bpc &&
-	    connector->display_info.bpc < mhdp->display_fmt.bpc)
-		dev_warn(mhdp->dev, "%s: Display bpc only %d < %d\n",
-			 __func__, connector->display_info.bpc,
-			 mhdp->display_fmt.bpc);
-
-	return num_modes;
-}
-
-static int cdns_mhdp_connector_detect(struct drm_connector *conn,
-				      struct drm_modeset_acquire_ctx *ctx,
-				      bool force)
-{
-	struct cdns_mhdp_device *mhdp = connector_to_mhdp(conn);
-
-	return cdns_mhdp_detect(mhdp);
-}
-
 static u32 cdns_mhdp_get_bpp(struct cdns_mhdp_display_fmt *fmt)
 {
 	u32 bpp;
@@ -1547,115 +1493,6 @@ bool cdns_mhdp_bandwidth_ok(struct cdns_mhdp_device *mhdp,
 	return true;
 }
 
-static
-enum drm_mode_status cdns_mhdp_mode_valid(struct drm_connector *conn,
-					  const struct drm_display_mode *mode)
-{
-	struct cdns_mhdp_device *mhdp = connector_to_mhdp(conn);
-
-	mutex_lock(&mhdp->link_mutex);
-
-	if (!cdns_mhdp_bandwidth_ok(mhdp, mode, mhdp->link.num_lanes,
-				    mhdp->link.rate)) {
-		mutex_unlock(&mhdp->link_mutex);
-		return MODE_CLOCK_HIGH;
-	}
-
-	mutex_unlock(&mhdp->link_mutex);
-	return MODE_OK;
-}
-
-static int cdns_mhdp_connector_atomic_check(struct drm_connector *conn,
-					    struct drm_atomic_state *state)
-{
-	struct cdns_mhdp_device *mhdp = connector_to_mhdp(conn);
-	struct drm_connector_state *old_state, *new_state;
-	struct drm_crtc_state *crtc_state;
-	u64 old_cp, new_cp;
-
-	if (!mhdp->hdcp_supported)
-		return 0;
-
-	old_state = drm_atomic_get_old_connector_state(state, conn);
-	new_state = drm_atomic_get_new_connector_state(state, conn);
-	old_cp = old_state->content_protection;
-	new_cp = new_state->content_protection;
-
-	if (old_state->hdcp_content_type != new_state->hdcp_content_type &&
-	    new_cp != DRM_MODE_CONTENT_PROTECTION_UNDESIRED) {
-		new_state->content_protection = DRM_MODE_CONTENT_PROTECTION_DESIRED;
-		goto mode_changed;
-	}
-
-	if (!new_state->crtc) {
-		if (old_cp == DRM_MODE_CONTENT_PROTECTION_ENABLED)
-			new_state->content_protection = DRM_MODE_CONTENT_PROTECTION_DESIRED;
-		return 0;
-	}
-
-	if (old_cp == new_cp ||
-	    (old_cp == DRM_MODE_CONTENT_PROTECTION_DESIRED &&
-	     new_cp == DRM_MODE_CONTENT_PROTECTION_ENABLED))
-		return 0;
-
-mode_changed:
-	crtc_state = drm_atomic_get_new_crtc_state(state, new_state->crtc);
-	crtc_state->mode_changed = true;
-
-	return 0;
-}
-
-static const struct drm_connector_helper_funcs cdns_mhdp_conn_helper_funcs = {
-	.detect_ctx = cdns_mhdp_connector_detect,
-	.get_modes = cdns_mhdp_get_modes,
-	.mode_valid = cdns_mhdp_mode_valid,
-	.atomic_check = cdns_mhdp_connector_atomic_check,
-};
-
-static const struct drm_connector_funcs cdns_mhdp_conn_funcs = {
-	.fill_modes = drm_helper_probe_single_connector_modes,
-	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
-	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
-	.reset = drm_atomic_helper_connector_reset,
-	.destroy = drm_connector_cleanup,
-};
-
-static int cdns_mhdp_connector_init(struct cdns_mhdp_device *mhdp)
-{
-	u32 bus_format = MEDIA_BUS_FMT_RGB121212_1X36;
-	struct drm_connector *conn = &mhdp->connector;
-	struct drm_bridge *bridge = &mhdp->bridge;
-	int ret;
-
-	conn->polled = DRM_CONNECTOR_POLL_HPD;
-
-	ret = drm_connector_init(bridge->dev, conn, &cdns_mhdp_conn_funcs,
-				 DRM_MODE_CONNECTOR_DisplayPort);
-	if (ret) {
-		dev_err(mhdp->dev, "Failed to initialize connector with drm\n");
-		return ret;
-	}
-
-	mhdp->connector_ptr = conn;
-	drm_connector_helper_add(conn, &cdns_mhdp_conn_helper_funcs);
-
-	ret = drm_display_info_set_bus_formats(&conn->display_info,
-					       &bus_format, 1);
-	if (ret)
-		return ret;
-
-	ret = drm_connector_attach_encoder(conn, bridge->encoder);
-	if (ret) {
-		dev_err(mhdp->dev, "Failed to attach connector to encoder\n");
-		return ret;
-	}
-
-	if (mhdp->hdcp_supported)
-		ret = drm_connector_attach_content_protection_property(conn, true);
-
-	return ret;
-}
-
 static int cdns_mhdp_attach(struct drm_bridge *bridge,
 			    struct drm_encoder *encoder,
 			    enum drm_bridge_attach_flags flags)
@@ -1672,9 +1509,11 @@ static int cdns_mhdp_attach(struct drm_bridge *bridge,
 		return ret;
 
 	if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)) {
-		ret = cdns_mhdp_connector_init(mhdp);
-		if (ret)
-			goto aux_unregister;
+		ret = -EINVAL;
+		dev_err(mhdp->dev,
+			"Connector initialisation not supported in bridge_attach %d\n",
+			ret);
+		goto aux_unregister;
 	}
 
 	spin_lock(&mhdp->start_lock);
@@ -2414,17 +2253,9 @@ static void cdns_mhdp_hpd_work(struct work_struct *work)
 	struct cdns_mhdp_device *mhdp = container_of(work,
 						     struct cdns_mhdp_device,
 						     hpd_work);
-	int ret;
+	cdns_mhdp_update_link_status(mhdp);
 
-	ret = cdns_mhdp_update_link_status(mhdp);
-	if (mhdp->connector_ptr) {
-		if (ret < 0)
-			schedule_work(&mhdp->modeset_retry_work);
-		else
-			drm_kms_helper_hotplug_event(mhdp->bridge.dev);
-	} else {
-		drm_bridge_hpd_notify(&mhdp->bridge, cdns_mhdp_detect(mhdp));
-	}
+	drm_bridge_hpd_notify(&mhdp->bridge, cdns_mhdp_detect(mhdp));
 }
 
 static int cdns_mhdp_probe(struct platform_device *pdev)
-- 
2.34.1

[PATCH v10 5/6] cadence: cdns-mhdp8546*: Change drm_connector from structure to pointer

[Harikrishna Shenoy]

From: Jayesh Choudhary <j-choudhary@ti.com>

Now that we have dropped the legacy code which became redundant with
introduction of DRM_BRIDGE_ATTACH_NO_CONNECTOR
usecase in driver,we can cleanly switch to drm_connector pointer
instead of structure.

Rename the connector_ptr member variable to connector for clarity and
consistency. The driver was using both connector and connector_ptr members,
but connector_ptr was the only one actually used throughout the code.
This change removes the unused connector struct member and renames
connector_ptr to connector for better readability.

This is purely a code cleanup change with no functional impact. All
references to connector_ptr are updated to use the renamed connector
variable throughout the driver.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>
---
 .../gpu/drm/bridge/cadence/cdns-mhdp8546-core.c    | 14 +++++++-------
 .../gpu/drm/bridge/cadence/cdns-mhdp8546-core.h    |  3 +--
 .../gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c    | 12 ++++++------
 3 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
index e3066dae340a6..f909469dacf08 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -1765,12 +1765,12 @@ static void cdns_mhdp_atomic_enable(struct drm_bridge *bridge,
 
 	mutex_lock(&mhdp->link_mutex);
 
-	mhdp->connector_ptr = drm_atomic_get_new_connector_for_encoder(state,
-								       bridge->encoder);
-	if (WARN_ON(!mhdp->connector_ptr))
+	mhdp->connector = drm_atomic_get_new_connector_for_encoder(state,
+								   bridge->encoder);
+	if (WARN_ON(!mhdp->connector))
 		goto out;
 
-	conn_state = drm_atomic_get_new_connector_state(state, mhdp->connector_ptr);
+	conn_state = drm_atomic_get_new_connector_state(state, mhdp->connector);
 	if (WARN_ON(!conn_state))
 		goto out;
 
@@ -1869,7 +1869,7 @@ static void cdns_mhdp_atomic_disable(struct drm_bridge *bridge,
 	if (mhdp->info && mhdp->info->ops && mhdp->info->ops->disable)
 		mhdp->info->ops->disable(mhdp);
 
-	mhdp->connector_ptr = NULL;
+	mhdp->connector = NULL;
 	mutex_unlock(&mhdp->link_mutex);
 }
 
@@ -1964,7 +1964,7 @@ static int cdns_mhdp_atomic_check(struct drm_bridge *bridge,
 	const struct drm_display_mode *mode = &crtc_state->adjusted_mode;
 	struct drm_connector_state *old_state, *new_state;
 	struct drm_atomic_state *state = crtc_state->state;
-	struct drm_connector *conn = mhdp->connector_ptr;
+	struct drm_connector *conn = mhdp->connector;
 	u64 old_cp, new_cp;
 
 	mutex_lock(&mhdp->link_mutex);
@@ -2179,7 +2179,7 @@ static void cdns_mhdp_modeset_retry_fn(struct work_struct *work)
 
 	mhdp = container_of(work, typeof(*mhdp), modeset_retry_work);
 
-	conn = mhdp->connector_ptr;
+	conn = mhdp->connector;
 
 	/* Grab the locks before changing connector property */
 	mutex_lock(&conn->dev->mode_config.mutex);
diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
index a76775c768956..b297db53ba283 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
@@ -375,8 +375,7 @@ struct cdns_mhdp_device {
 	 */
 	struct mutex link_mutex;
 
-	struct drm_connector connector;
-	struct drm_connector *connector_ptr;
+	struct drm_connector *connector;
 	struct drm_bridge bridge;
 
 	struct cdns_mhdp_link link;
diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c
index 21a7d2fb266e4..5cd0b873e16f9 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c
@@ -394,7 +394,7 @@ static int _cdns_mhdp_hdcp_disable(struct cdns_mhdp_device *mhdp)
 	int ret;
 
 	dev_dbg(mhdp->dev, "[%s:%d] HDCP is being disabled...\n",
-		mhdp->connector_ptr->name, mhdp->connector_ptr->base.id);
+		mhdp->connector->name, mhdp->connector->base.id);
 
 	ret = cdns_mhdp_hdcp_set_config(mhdp, 0, false);
 
@@ -437,7 +437,7 @@ static int cdns_mhdp_hdcp_check_link(struct cdns_mhdp_device *mhdp)
 
 	mutex_lock(&mhdp->hdcp.mutex);
 
-	if (!mhdp->connector_ptr)
+	if (!mhdp->connector)
 		goto out;
 
 	if (mhdp->hdcp.value == DRM_MODE_CONTENT_PROTECTION_UNDESIRED)
@@ -449,7 +449,7 @@ static int cdns_mhdp_hdcp_check_link(struct cdns_mhdp_device *mhdp)
 
 	dev_err(mhdp->dev,
 		"[%s:%d] HDCP link failed, retrying authentication\n",
-		mhdp->connector_ptr->name, mhdp->connector_ptr->base.id);
+		mhdp->connector->name, mhdp->connector->base.id);
 
 	ret = _cdns_mhdp_hdcp_disable(mhdp);
 	if (ret) {
@@ -494,8 +494,8 @@ static void cdns_mhdp_hdcp_prop_work(struct work_struct *work)
 	struct drm_device *dev = NULL;
 	struct drm_connector_state *state;
 
-	if (mhdp->connector_ptr)
-		dev = mhdp->connector_ptr->dev;
+	if (mhdp->connector)
+		dev = mhdp->connector->dev;
 
 	if (!dev)
 		return;
@@ -503,7 +503,7 @@ static void cdns_mhdp_hdcp_prop_work(struct work_struct *work)
 	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
 	mutex_lock(&mhdp->hdcp.mutex);
 	if (mhdp->hdcp.value != DRM_MODE_CONTENT_PROTECTION_UNDESIRED) {
-		state = mhdp->connector_ptr->state;
+		state = mhdp->connector->state;
 		state->content_protection = mhdp->hdcp.value;
 	}
 	mutex_unlock(&mhdp->hdcp.mutex);
-- 
2.34.1

[PATCH v10 6/6] drm/bridge: cadence: cdns-mhdp8546-core: Reduce log level for DPCD read/write

[Harikrishna Shenoy]

From: Jayesh Choudhary <j-choudhary@ti.com>

Reduce the log level for cdns_mhdp_dpcd_read and cdns_mhdp_dpcd_write
errors in cdns_mhdp_transfer function as in case of failure, there is
flooding of these prints along with other indicators like EDID failure
logs which are fairly intuitive in themselves rendering these error logs
useless.
Also, the caller functions for the cdns_mhdp_transfer in drm_dp_helper.c
(which calls it 32 times), has debug log level in case transfer fails.
So having a superseding log level in cdns_mhdp_transfer seems bad.

Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>
---
 drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
index f909469dacf08..1f7c642ad0148 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -778,7 +778,7 @@ static ssize_t cdns_mhdp_transfer(struct drm_dp_aux *aux,
 			if (!ret)
 				continue;
 
-			dev_err(mhdp->dev,
+			dev_dbg(mhdp->dev,
 				"Failed to write DPCD addr %u\n",
 				msg->address + i);
 
@@ -788,7 +788,7 @@ static ssize_t cdns_mhdp_transfer(struct drm_dp_aux *aux,
 		ret = cdns_mhdp_dpcd_read(mhdp, msg->address,
 					  msg->buffer, msg->size);
 		if (ret) {
-			dev_err(mhdp->dev,
+			dev_dbg(mhdp->dev,
 				"Failed to read DPCD addr %u\n",
 				msg->address);
 
-- 
2.34.1

Re: [PATCH v10 1/6] drm/bridge: cadence: cdns-mhdp8546-core: Set the mhdp connector earlier in atomic_enable()

[Tomi Valkeinen]

Hi,

On 09/12/2025 14:03, Harikrishna Shenoy wrote:
> From: Jayesh Choudhary <j-choudhary@ti.com>
> 
> In case if we get errors in cdns_mhdp_link_up() or cdns_mhdp_reg_read()
> in atomic_enable, we will go to cdns_mhdp_modeset_retry_fn() and will hit
> NULL pointer while trying to access the mutex. We need the connector to
> be set before that. Unlike in legacy cases with flag
> !DRM_BRIDGE_ATTACH_NO_CONNECTOR, we do not have connector initialised
> in bridge_attach(), so add the mhdp->connector_ptr in device structure
> to handle both cases with DRM_BRIDGE_ATTACH_NO_CONNECTOR and
> !DRM_BRIDGE_ATTACH_NO_CONNECTOR, set it in atomic_enable() earlier to
> avoid possible NULL pointer dereference in recovery paths like
> modeset_retry_fn() with the DRM_BRIDGE_ATTACH_NO_CONNECTOR flag set.
> 
> Fixes: c932ced6b585 ("drm/tidss: Update encoder/bridge chain connect model")
> Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
> Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>
> ---
>  .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 29 ++++++++++---------
>  .../drm/bridge/cadence/cdns-mhdp8546-core.h   |  1 +
>  .../drm/bridge/cadence/cdns-mhdp8546-hdcp.c   | 18 +++++++++---
>  3 files changed, 30 insertions(+), 18 deletions(-)
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

 Tomi

Re: [PATCH v10 3/6] drm/bridge: cadence: cdns-mhdp8546-core: Handle HDCP state in bridge atomic check

[Tomi Valkeinen]

Hi,

On 09/12/2025 14:03, Harikrishna Shenoy wrote:
> Now that we have DRM_BRIDGE_ATTACH_NO_CONNECTOR framework, handle the
> HDCP state change in bridge atomic check as well to enable correct
> functioning for HDCP in both DRM_BRIDGE_ATTACH_NO_CONNECTOR and
> !DRM_BRIDGE_ATTACH_NO_CONNECTOR case.
> 
> Without this patch, when using DRM_BRIDGE_ATTACH_NO_CONNECTOR flag, HDCP
> state changes would not be properly handled during atomic commits,
> potentially leading to HDCP authentication failures or incorrect
> protection status for content requiring HDCP encryption.
> 
> Fixes: 6a3608eae6d33 ("drm: bridge: cdns-mhdp8546: Enable HDCP")
> Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>
> ---
>  .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 23 +++++++++++++++++++
>  1 file changed, 23 insertions(+)
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

 Tomi

Re: [PATCH v10 4/6] drm/bridge: cadence: cdns-mhdp8546-core: Remove legacy support for connector initialisation in bridge

[Tomi Valkeinen]

Hi,

On 09/12/2025 14:03, Harikrishna Shenoy wrote:
> From: Jayesh Choudhary <j-choudhary@ti.com>
> 
> Now that this bridge supports DRM_BRIDGE_ATTACH_NO_CONNECTOR,
> and only TI K3 platforms consume this driver and
> tidss (their display controller) has DRM_BRIDGE_ATTACH_NO_CONNECTOR
> flag set,we can remove the legacy code for the
> non-DRM_BRIDGE_ATTACH_NO_CONNECTOR case.
> 
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
> Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
> Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>
> ---
>  .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 187 +-----------------
>  1 file changed, 9 insertions(+), 178 deletions(-)
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

 Tomi

Re: [PATCH v10 5/6] cadence: cdns-mhdp8546*: Change drm_connector from structure to pointer

[Tomi Valkeinen]

Hi,

On 09/12/2025 14:03, Harikrishna Shenoy wrote:
> From: Jayesh Choudhary <j-choudhary@ti.com>
> 
> Now that we have dropped the legacy code which became redundant with
> introduction of DRM_BRIDGE_ATTACH_NO_CONNECTOR
> usecase in driver,we can cleanly switch to drm_connector pointer
> instead of structure.
> 
> Rename the connector_ptr member variable to connector for clarity and
> consistency. The driver was using both connector and connector_ptr members,
> but connector_ptr was the only one actually used throughout the code.
> This change removes the unused connector struct member and renames
> connector_ptr to connector for better readability.
> 
> This is purely a code cleanup change with no functional impact. All
> references to connector_ptr are updated to use the renamed connector
> variable throughout the driver.
> 
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
> Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
> Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>
> ---
>  .../gpu/drm/bridge/cadence/cdns-mhdp8546-core.c    | 14 +++++++-------
>  .../gpu/drm/bridge/cadence/cdns-mhdp8546-core.h    |  3 +--
>  .../gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c    | 12 ++++++------
>  3 files changed, 14 insertions(+), 15 deletions(-)

Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

 Tomi

Re: [PATCH v10 0/6] MHDP8546 fixes related to DRM_BRIDGE_ATTACH_NO_CONNECTOR usecase

[Beleswar Prasad Padhi]

Hi All,

On 09/12/25 17:33, Harikrishna Shenoy wrote:
> With the DRM_BRIDGE_ATTACH_NO_CONNECTOR framework, the connector is 
> no longer initialized in  bridge_attach() when the display controller 
> sets the DRM_BRIDGE_ATTACH_NO_CONNECTOR flag. 
> This causes a null pointer dereference in cdns_mhdp_modeset_retry_fn() 
> when trying to access &conn->dev->mode_config.mutex. 
> Observed on a board where EDID read failed. 
> (log: https://gist.github.com/Jayesh2000/233f87f9becdf1e66f1da6fd53f77429)
>
> Patch 1 adds a connector_ptr which takes care of both 
> DRM_BRIDGE_ATTACH_NO_CONNECTOR and !DRM_BRIDGE_ATTACH_NO_CONNECTOR 
> case by setting the pointer in appropriate hooks and checking for pointer 
> validity before accessing the connector.
> Patch 2 adds mode validation hook to bridge fucntions.
> Patch 3 fixes HDCP to work with both DRM_BRIDGE_ATTACH_NO_CONNECTOR 
> and !DRM_BRIDGE_ATTACH_NO_CONNECTOR case by moving HDCP state handling 
> into the bridge atomic check inline with the 
> DRM_BRIDGE_ATTACH_NO_CONNECTOR model.
> Patches 4,5 do necessary cleanup and alignment for using
> connector pointer.
>
> The rationale behind the sequence of commits is we can cleanly 
> switch to drm_connector pointer after removal of connector helper 
> code blocks, which are anyways not touch after 
> DRM_BRIDGE_ATTACH_NO_CONNECTOR has been enabled in driver.
>
> The last patch make smaller adjustment: lowering the log level for
> noisy DPCD transfer errors.


A gentle ping for this series. This has received multiple R/Bs.
Please help with a review/merge of this series.

Thanks,
Beleswar

[...]

Re: [PATCH v10 1/6] drm/bridge: cadence: cdns-mhdp8546-core: Set the mhdp connector earlier in atomic_enable()

[Luca Ceresoli]

On Tue Dec 9, 2025 at 1:03 PM CET, Harikrishna Shenoy wrote:
> From: Jayesh Choudhary <j-choudhary@ti.com>
>
> In case if we get errors in cdns_mhdp_link_up() or cdns_mhdp_reg_read()
> in atomic_enable, we will go to cdns_mhdp_modeset_retry_fn() and will hit
> NULL pointer while trying to access the mutex. We need the connector to
> be set before that. Unlike in legacy cases with flag
> !DRM_BRIDGE_ATTACH_NO_CONNECTOR, we do not have connector initialised
> in bridge_attach(), so add the mhdp->connector_ptr in device structure
> to handle both cases with DRM_BRIDGE_ATTACH_NO_CONNECTOR and
> !DRM_BRIDGE_ATTACH_NO_CONNECTOR, set it in atomic_enable() earlier to
> avoid possible NULL pointer dereference in recovery paths like
> modeset_retry_fn() with the DRM_BRIDGE_ATTACH_NO_CONNECTOR flag set.
>
> Fixes: c932ced6b585 ("drm/tidss: Update encoder/bridge chain connect model")
> Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
> Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>

Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v10 2/6] drm/bridge: cadence: cdns-mhdp8546-core: Add mode_valid hook to drm_bridge_funcs

[Luca Ceresoli]

On Tue Dec 9, 2025 at 1:03 PM CET, Harikrishna Shenoy wrote:
> From: Jayesh Choudhary <j-choudhary@ti.com>
>
> Add cdns_mhdp_bridge_mode_valid() to check if specific mode is valid for
> this bridge or not. In the legacy usecase with
> !DRM_BRIDGE_ATTACH_NO_CONNECTOR we were using the hook from
> drm_connector_helper_funcs but with DRM_BRIDGE_ATTACH_NO_CONNECTOR
> we need to have mode_valid() in drm_bridge_funcs.
>
> Without this patch, when using DRM_BRIDGE_ATTACH_NO_CONNECTOR
> flag, the cdns_mhdp_bandwidth_ok() function would not be called
> during  mode validation, potentially allowing modes that exceed
> the bridge's bandwidth capabilities to be incorrectly marked as
> valid.
>
> Fixes: c932ced6b585 ("drm/tidss: Update encoder/bridge chain connect model")
> Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
> Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>

Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v10 3/6] drm/bridge: cadence: cdns-mhdp8546-core: Handle HDCP state in bridge atomic check

[Luca Ceresoli]

On Tue Dec 9, 2025 at 1:03 PM CET, Harikrishna Shenoy wrote:
> Now that we have DRM_BRIDGE_ATTACH_NO_CONNECTOR framework, handle the
> HDCP state change in bridge atomic check as well to enable correct
> functioning for HDCP in both DRM_BRIDGE_ATTACH_NO_CONNECTOR and
> !DRM_BRIDGE_ATTACH_NO_CONNECTOR case.
>
> Without this patch, when using DRM_BRIDGE_ATTACH_NO_CONNECTOR flag, HDCP
> state changes would not be properly handled during atomic commits,
> potentially leading to HDCP authentication failures or incorrect
> protection status for content requiring HDCP encryption.
>
> Fixes: 6a3608eae6d33 ("drm: bridge: cdns-mhdp8546: Enable HDCP")
> Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>

Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v10 4/6] drm/bridge: cadence: cdns-mhdp8546-core: Remove legacy support for connector initialisation in bridge

[Luca Ceresoli]

On Tue Dec 9, 2025 at 1:03 PM CET, Harikrishna Shenoy wrote:
> From: Jayesh Choudhary <j-choudhary@ti.com>
>
> Now that this bridge supports DRM_BRIDGE_ATTACH_NO_CONNECTOR,
> and only TI K3 platforms consume this driver and
> tidss (their display controller) has DRM_BRIDGE_ATTACH_NO_CONNECTOR
> flag set,we can remove the legacy code for the
> non-DRM_BRIDGE_ATTACH_NO_CONNECTOR case.
>
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
> Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
> Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>

Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v10 5/6] cadence: cdns-mhdp8546*: Change drm_connector from structure to pointer

[Luca Ceresoli]

On Tue Dec 9, 2025 at 1:03 PM CET, Harikrishna Shenoy wrote:
> From: Jayesh Choudhary <j-choudhary@ti.com>
>
> Now that we have dropped the legacy code which became redundant with
> introduction of DRM_BRIDGE_ATTACH_NO_CONNECTOR
> usecase in driver,we can cleanly switch to drm_connector pointer
> instead of structure.
>
> Rename the connector_ptr member variable to connector for clarity and
> consistency. The driver was using both connector and connector_ptr members,
> but connector_ptr was the only one actually used throughout the code.
> This change removes the unused connector struct member and renames
> connector_ptr to connector for better readability.
>
> This is purely a code cleanup change with no functional impact. All
> references to connector_ptr are updated to use the renamed connector
> variable throughout the driver.
>
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
> Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
> Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>

Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v10 6/6] drm/bridge: cadence: cdns-mhdp8546-core: Reduce log level for DPCD read/write

[Luca Ceresoli]

On Tue Dec 9, 2025 at 1:03 PM CET, Harikrishna Shenoy wrote:
> From: Jayesh Choudhary <j-choudhary@ti.com>
>
> Reduce the log level for cdns_mhdp_dpcd_read and cdns_mhdp_dpcd_write
> errors in cdns_mhdp_transfer function as in case of failure, there is
> flooding of these prints along with other indicators like EDID failure
> logs which are fairly intuitive in themselves rendering these error logs
> useless.
> Also, the caller functions for the cdns_mhdp_transfer in drm_dp_helper.c
> (which calls it 32 times), has debug log level in case transfer fails.
> So having a superseding log level in cdns_mhdp_transfer seems bad.
>
> Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
> Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>

Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v10 0/6] MHDP8546 fixes related to DRM_BRIDGE_ATTACH_NO_CONNECTOR usecase

[Luca Ceresoli]

On Tue, 09 Dec 2025 17:33:26 +0530, Harikrishna Shenoy wrote:
> With the DRM_BRIDGE_ATTACH_NO_CONNECTOR framework, the connector is
> no longer initialized in  bridge_attach() when the display controller
> sets the DRM_BRIDGE_ATTACH_NO_CONNECTOR flag.
> This causes a null pointer dereference in cdns_mhdp_modeset_retry_fn()
> when trying to access &conn->dev->mode_config.mutex.
> Observed on a board where EDID read failed.
> (log: https://gist.github.com/Jayesh2000/233f87f9becdf1e66f1da6fd53f77429)
> 
> [...]

Applied, thanks!

[1/6] drm/bridge: cadence: cdns-mhdp8546-core: Set the mhdp connector earlier in atomic_enable()
      commit: 43d6508ddbf9fb974fbc359a033154f78c9d4c8b
[2/6] drm/bridge: cadence: cdns-mhdp8546-core: Add mode_valid hook to drm_bridge_funcs
      commit: 6dbff34016052b099558b76632e4983e2df13fed
[3/6] drm/bridge: cadence: cdns-mhdp8546-core: Handle HDCP state in bridge atomic check
      commit: 4a8edd658489ec2a3d7e20482fa9e8d366153d8d
[4/6] drm/bridge: cadence: cdns-mhdp8546-core: Remove legacy support for connector initialisation in bridge
      commit: 35cf2554520c8ec59f12e08ded72ed11895fffc6
[5/6] cadence: cdns-mhdp8546*: Change drm_connector from structure to pointer
      commit: 0d9e84d304575029815681e06f755075c64ee85d
[6/6] drm/bridge: cadence: cdns-mhdp8546-core: Reduce log level for DPCD read/write
      commit: bfb18fd193e2413f02ad934e46887f415f0ce4ec

Best regards,
-- 
Luca Ceresoli <luca.ceresoli@bootlin.com>