[PATCH 21/26] drm/atomic-helper: nonblocking commit support

Daniel Vetter
2016-05-29T18:35:18Z

Design ideas:

- split up the actual commit into different phases, and have
completions for each of them. This will be useful for the future
when we want to interleave phases much more aggressively, for e.g.
queue depth > 1. For not it's just a minimal optimization compared
to current common nonblocking implementation patterns from drivers,
which all stall for the entire commit to complete, including vblank
waits and cleanups.

- Extract a separate atomic_commit_hw hook since that's the part most
drivers will need to overwrite, hopefully allowing even more shared
code.

- Enforce EBUSY seamntics by attaching one of the completions to the
flip_done vblank event. Side benefit of forcing atomic drivers using
these helpers to implement event handlign at least semi-correct. I'm
evil that way ;-)

- Ridiculously modular, as usual.

- The main tracking unit for a commit stays struct drm_atomic_state,
and the ownership rules for that are unchanged. Ownership still
gets transferred to the driver (and subsequently to the worker) on
successful commits. What is added is a small, per-crtc, refcounted
structure to track pending commits called struct drm_crtc_commit.
No actual state is attached to that though, it's purely for ordering
and waiting.

- Dependencies are implicitly handled by assuming that any CRTC part
of &drm_atomic_state is a dependency, and that the current commit
must wait for any commits to complete on those CRTC. This way
drivers can easily add more depencies using
drm_atomic_get_crtc_state(), which is very natural since in most
case a dependency exists iff there's some bit of state that needs to
be cross checked.

Removing depencies is not possible, drivers simply need to be
careful to not include every CRTC in a commit if that's not
necessary. Which is a good idea anyway, since that also avoids
ww_mutex lock contention.

- Queue depth > 1 sees some prep work in this patch by adding a stall
paramater to drm_atomic_helper_swap_states(). To be able to push
commits entirely free-standing and in a deeper queue through the
back-end the driver must not access any obj->state pointers. This
means we need to track the old state in drm_atomic_state (much
easier with the consolidated arrays), and pass them all explicitly
to driver backends (this will be serious amounts of churn).

Once that's done stall can be set to false in swap_states.

Features: Contains bugs because totally untested.

v2: Dont ask for flip_done signalling when the CRTC is off and stays
off: Drivers don't handle events in that case. Instead complete right
away. This way future commits don't need to have special-case logic,
but can keep blocking for the flip_done completion.

v3: Tons of fixes:
- Stall for preceeding commit for real, not the current one by
accident.
- Add WARN_ON in case drivers don't fire the drm event.
- Don't double-free drm events.

v4: Make legacy cursor not stall.

v5: Extend the helper hook to cover the entire commit tail. Some
drivers need special code for cleanup and vblank waiting, this makes
it a bit more useful. Inspired by the rockchip driver.

v6: Add WARN_ON to catch drivers who forget to send out the
drm event.

Cc: Tomeu Vizoso <tomeu.vizoso@gmail.com>
Cc: Daniel Stone <daniels@collabora.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
---
drivers/gpu/drm/drm_atomic.c | 22 ++
drivers/gpu/drm/drm_atomic_helper.c | 366 ++++++++++++++++++++++++++++---
drivers/gpu/drm/drm_crtc.c | 3 +
drivers/gpu/drm/drm_fops.c | 6 +
include/drm/drmP.h | 1 +
include/drm/drm_atomic.h | 6 +
include/drm/drm_atomic_helper.h | 8 +
include/drm/drm_crtc.h | 119 +++++++++-
include/drm/drm_modeset_helper_vtables.h | 36 +++
9 files changed, 534 insertions(+), 33 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 1db198df3014..50aa341ca9ff 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -33,6 +33,20 @@

#include "drm_crtc_internal.h"

+static void crtc_commit_free(struct kref *kref)
+{
+ struct drm_crtc_commit *commit =
+ container_of(kref, struct drm_crtc_commit, ref);
+
+ kfree(commit);
+}
+
+void drm_crtc_commit_put(struct drm_crtc_commit *commit)
+{
+ kref_put(&commit->ref, crtc_commit_free);
+}
+EXPORT_SYMBOL(drm_crtc_commit_put);
+
/**
* drm_atomic_state_default_release -
* release memory initialized by drm_atomic_state_init
@@ -148,6 +162,14 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)

crtc->funcs->atomic_destroy_state(crtc,
state->crtcs[i].state);
+
+ if (state->crtcs[i].commit) {
+ kfree(state->crtcs[i].commit->event);
+ state->crtcs[i].commit->event = NULL;
+ drm_crtc_commit_put(state->crtcs[i].commit);
+ }
+
+ state->crtcs[i].commit = NULL;
state->crtcs[i].ptr = NULL;
state->crtcs[i].state = NULL;
}
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index fecbb52cbb85..a5854a31f493 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1113,20 +1113,15 @@ drm_atomic_helper_wait_for_vblanks(struct drm_device *dev,
EXPORT_SYMBOL(drm_atomic_helper_wait_for_vblanks);

/**
- * drm_atomic_helper_commit - commit validated state object
- * @dev: DRM device
- * @state: the driver state object
- * @nonblocking: whether nonblocking behavior is requested.
+ * drm_atomic_helper_commit_tail - commit atomic update to hardware
+ * @state: new modeset state to be committed
*
- * This function commits a with drm_atomic_helper_check() pre-validated state
- * object. This can still fail when e.g. the framebuffer reservation fails. For
- * now this doesn't implement nonblocking commits.
+ * This is the default implemenation for the ->atomic_commit_tail() hook of the
+ * &drm_mode_config_helper_funcs vtable.
*
- * Note that right now this function does not support nonblocking commits, hence
- * driver writers must implement their own version for now. Also note that the
- * default ordering of how the various stages are called is to match the legacy
- * modeset helper library closest. One peculiarity of that is that it doesn't
- * mesh well with runtime PM at all.
+ * Note that the default ordering of how the various stages are called is to
+ * match the legacy modeset helper library closest. One peculiarity of that is
+ * that it doesn't mesh well with runtime PM at all.
*
* For drivers supporting runtime PM the recommended sequence is
*
@@ -1137,6 +1132,70 @@ EXPORT_SYMBOL(drm_atomic_helper_wait_for_vblanks);
* drm_atomic_helper_commit_planes(dev, state, true);
*
* See the kerneldoc entries for these three functions for more details.
+ */
+void drm_atomic_helper_commit_tail(struct drm_atomic_state *state)
+{
+ struct drm_device *dev = state->dev;
+
+ drm_atomic_helper_commit_modeset_disables(dev, state);
+
+ drm_atomic_helper_commit_planes(dev, state, false);
+
+ drm_atomic_helper_commit_modeset_enables(dev, state);
+
+ drm_atomic_helper_commit_hw_done(state);
+
+ drm_atomic_helper_wait_for_vblanks(dev, state);
+
+ drm_atomic_helper_cleanup_planes(dev, state);
+}
+EXPORT_SYMBOL(drm_atomic_helper_commit_tail);
+
+void commit_tail(struct drm_atomic_state *state)
+{
+ struct drm_device *dev = state->dev;
+ struct drm_mode_config_helper_funcs *funcs;
+
+ funcs = dev->mode_config.helper_private;
+
+ drm_atomic_helper_wait_for_fences(dev, state);
+
+ drm_atomic_helper_wait_for_dependencies(state);
+
+ if (funcs && funcs->atomic_commit_tail)
+ funcs->atomic_commit_tail(state);
+ else
+ drm_atomic_helper_commit_tail(state);
+
+ drm_atomic_helper_commit_cleanup_done(state);
+
+ drm_atomic_state_free(state);
+}
+
+static void commit_work(struct work_struct *work)
+{
+ struct drm_atomic_state *state = container_of(work,
+ struct drm_atomic_state,
+ commit_work);
+ commit_tail(state);
+}
+
+/**
+ * drm_atomic_helper_commit - commit validated state object
+ * @dev: DRM device
+ * @state: the driver state object
+ * @nonblocking: whether nonblocking behavior is requested.
+ *
+ * This function commits a with drm_atomic_helper_check() pre-validated state
+ * object. This can still fail when e.g. the framebuffer reservation fails. For
+ * now this doesn't implement nonblocking commits.
+ *
+ * Note that right now this function does not support nonblocking commits, hence
+ * driver writers must implement their own version for now.
+ *
+ * Committing the actual hardware state is done through the
+ * ->atomic_commit_tail() callback of the &drm_mode_config_helper_funcs vtable,
+ * or it's default implementation drm_atomic_helper_commit_tail().
*
* RETURNS
* Zero for success or -errno.
@@ -1147,8 +1206,11 @@ int drm_atomic_helper_commit(struct drm_device *dev,
{
int ret;

- if (nonblock)
- return -EBUSY;
+ ret = drm_atomic_helper_setup_commit(state, nonblock);
+ if (ret)
+ return ret;
+
+ INIT_WORK(&state->commit_work, commit_work);

ret = drm_atomic_helper_prepare_planes(dev, state);
if (ret)
@@ -1176,21 +1238,16 @@ int drm_atomic_helper_commit(struct drm_device *dev,
* update. Which is important since compositors need to figure out the
* composition of the next frame right after having submitted the
* current layout.
+ *
+ * NOTE: Commit work has multiple phases, first hardware commit, then
+ * cleanup. We want them to overlap, hence need system_unbound_wq to
+ * make sure work items don't artifically stall on each another.
*/

- drm_atomic_helper_wait_for_fences(dev, state);
-
- drm_atomic_helper_commit_modeset_disables(dev, state);
-
- drm_atomic_helper_commit_planes(dev, state, false);
-
- drm_atomic_helper_commit_modeset_enables(dev, state);
-
- drm_atomic_helper_wait_for_vblanks(dev, state);
-
- drm_atomic_helper_cleanup_planes(dev, state);
-
- drm_atomic_state_free(state);
+ if (nonblock)
+ queue_work(system_unbound_wq, &state->commit_work);
+ else
+ commit_tail(state);

return 0;
}
@@ -1234,6 +1291,225 @@ EXPORT_SYMBOL(drm_atomic_helper_commit);
* being displayed.
*/

+static int stall_checks(struct drm_crtc *crtc, bool nonblock)
+{
+ struct drm_crtc_commit *commit, *stall_commit = NULL;
+ bool completed = true;
+ int i, ret = 0;
+
+ spin_lock(&crtc->commit_lock);
+ i = 0;
+ list_for_each_entry(commit, &crtc->commit_list, commit_entry) {
+ if (i == 0) {
+ completed = try_wait_for_completion(&commit->flip_done);
+ /* Userspace is not allowed to get ahead of the previous
+ * commit with nonblocking ones. */
+ if (!completed && nonblock) {
+ spin_unlock(&crtc->commit_lock);
+ return -EBUSY;
+ }
+ } else if (i == 1) {
+ stall_commit = commit;
+ drm_crtc_commit_get(stall_commit);
+ } else
+ break;
+
+ i++;
+ }
+ spin_unlock(&crtc->commit_lock);
+
+ if (!stall_commit)
+ return 0;
+
+ /* We don't want to let commits get ahead of cleanup work too much,
+ * stalling on 2nd previous commit means triple-buffer won't ever stall.
+ */
+ ret = wait_for_completion_interruptible_timeout(&commit->cleanup_done,
+ 10*HZ);
+ if (ret == 0)
+ DRM_ERROR("[CRTC:%d:%s] cleanup_done timed out\n",
+ crtc->base.id, crtc->name);
+
+ if (ret == -ERESTARTSYS)
+ ret = -EINTR;
+
+ drm_crtc_commit_put(stall_commit);
+
+ return ret;
+}
+
+/**
+ * drm_atomic_helper_setup_commit - setup possible nonblocking commit
+ *
+ * Returns:
+ *
+ * 0 on success. -EBUSY when userspace schedules nonblocking commits too fast,
+ * -ENOMEM on allocation failures and -EINTR when a signal is pending.
+ */
+int drm_atomic_helper_setup_commit(struct drm_atomic_state *state,
+ bool nonblock)
+{
+ struct drm_crtc *crtc;
+ struct drm_crtc_state *crtc_state;
+ struct drm_crtc_commit *commit;
+ int i, ret;
+
+ for_each_crtc_in_state(state, crtc, crtc_state, i) {
+ commit = kzalloc(sizeof(*commit), GFP_KERNEL);
+ if (!commit)
+ return -ENOMEM;
+
+ init_completion(&commit->flip_done);
+ init_completion(&commit->hw_done);
+ init_completion(&commit->cleanup_done);
+ INIT_LIST_HEAD(&commit->commit_entry);
+ kref_init(&commit->ref);
+ commit->crtc = crtc;
+
+ state->crtcs[i].commit = commit;
+
+ ret = stall_checks(crtc, nonblock);
+ if (ret)
+ return ret;
+
+ /* Drivers only send out events when at least either current or
+ * new CRTC state is active. Complete right away if everything
+ * stays off. */
+ if (!crtc->state->active && !crtc_state->active) {
+ complete_all(&commit->flip_done);
+ continue;
+ }
+
+ /* Legacy cursor updates are fully unsynced. */
+ if (state->legacy_cursor_update) {
+ complete_all(&commit->flip_done);
+ continue;
+ }
+
+ if (!crtc_state->event) {
+ commit->event = kzalloc(sizeof(*commit->event),
+ GFP_KERNEL);
+ if (!commit->event)
+ return -ENOMEM;
+
+ crtc_state->event = commit->event;
+ }
+
+ crtc_state->event->base.completion = &commit->flip_done;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL(drm_atomic_helper_setup_commit);
+
+
+static struct drm_crtc_commit *preceeding_commit(struct drm_crtc *crtc)
+{
+ struct drm_crtc_commit *commit;
+ int i = 0;
+
+ list_for_each_entry(commit, &crtc->commit_list, commit_entry) {
+ /* skip the first entry, that's the current commit */
+ if (i == 1)
+ return commit;
+ i++;
+ }
+
+ return NULL;
+}
+
+void drm_atomic_helper_wait_for_dependencies(struct drm_atomic_state *state)
+{
+ struct drm_crtc *crtc;
+ struct drm_crtc_state *crtc_state;
+ struct drm_crtc_commit *commit;
+ int i;
+ long ret;
+
+ for_each_crtc_in_state(state, crtc, crtc_state, i) {
+ spin_lock(&crtc->commit_lock);
+ commit = preceeding_commit(crtc);
+ if (commit)
+ drm_crtc_commit_get(commit);
+ spin_unlock(&crtc->commit_lock);
+
+ if (!commit)
+ continue;
+
+ ret = wait_for_completion_timeout(&commit->hw_done,
+ 10*HZ);
+ if (ret == 0)
+ DRM_ERROR("[CRTC:%d:%s] hw_done timed out\n",
+ crtc->base.id, crtc->name);
+
+ /* Currently no support for overwriting flips, hence
+ * stall for previous one to execute completely. */
+ ret = wait_for_completion_timeout(&commit->flip_done,
+ 10*HZ);
+ if (ret == 0)
+ DRM_ERROR("[CRTC:%d:%s] flip_done timed out\n",
+ crtc->base.id, crtc->name);
+
+ drm_crtc_commit_put(commit);
+ }
+}
+EXPORT_SYMBOL(drm_atomic_helper_wait_for_dependencies);
+
+void drm_atomic_helper_commit_hw_done(struct drm_atomic_state *state)
+{
+ struct drm_crtc *crtc;
+ struct drm_crtc_state *crtc_state;
+ struct drm_crtc_commit *commit;
+ int i;
+
+ for_each_crtc_in_state(state, crtc, crtc_state, i) {
+ commit = state->crtcs[i].commit;
+ if (!commit)
+ continue;
+
+ /* backend must have consumed any event by now */
+ WARN_ON(crtc->state->event);
+ spin_lock(&crtc->commit_lock);
+ complete_all(&commit->hw_done);
+ spin_unlock(&crtc->commit_lock);
+ }
+}
+EXPORT_SYMBOL(drm_atomic_helper_commit_hw_done);
+
+void drm_atomic_helper_commit_cleanup_done(struct drm_atomic_state *state)
+{
+ struct drm_crtc *crtc;
+ struct drm_crtc_state *crtc_state;
+ struct drm_crtc_commit *commit;
+ int i;
+ long ret;
+
+ for_each_crtc_in_state(state, crtc, crtc_state, i) {
+ commit = state->crtcs[i].commit;
+ if (!commit)
+ continue;
+ spin_lock(&crtc->commit_lock);
+ complete_all(&commit->cleanup_done);
+
+ WARN_ON(!try_wait_for_completion(&commit->hw_done));
+
+ /* commit_list borrows our reference, need to remove before we
+ * clean up our drm_atomic_state. */
+ list_del(&commit->commit_entry);
+ spin_unlock(&crtc->commit_lock);
+
+ /* We must wait for the vblank event to signal our completion
+ * before releasing our reference, since the vblank work does
+ * not hold a reference of its own. */
+ ret = wait_for_completion_timeout(&commit->flip_done,
+ 10*HZ);
+ if (ret == 0)
+ DRM_ERROR("[CRTC:%d:%s] flip_done timed out\n",
+ crtc->base.id, crtc->name);
+ }
+}
+EXPORT_SYMBOL(drm_atomic_helper_commit_cleanup_done);
+
/**
* drm_atomic_helper_prepare_planes - prepare plane resources before commit
* @dev: DRM device
@@ -1553,17 +1829,44 @@ EXPORT_SYMBOL(drm_atomic_helper_cleanup_planes);
*
* 5. Call drm_atomic_helper_cleanup_planes() with @state, which since step 3
* contains the old state. Also do any other cleanup required with that state.
+ *
+ * @stall must be set when nonblocking commits for this driver directly access
+ * the ->state pointer of &drm_plane, &drm_crtc or &drm_connector. With the
+ * current atomic helpers this is almost always the case, since the helpers
+ * don't pass the right state structures to the callbacks.
*/
void drm_atomic_helper_swap_state(struct drm_atomic_state *state,
bool stall)
{
int i;
+ long ret;
struct drm_connector *connector;
struct drm_connector_state *conn_state;
struct drm_crtc *crtc;
struct drm_crtc_state *crtc_state;
struct drm_plane *plane;
struct drm_plane_state *plane_state;
+ struct drm_crtc_commit *commit;
+
+ if (stall) {
+ for_each_crtc_in_state(state, crtc, crtc_state, i) {
+ spin_lock(&crtc->commit_lock);
+ commit = preceeding_commit(crtc);
+ if (commit)
+ drm_crtc_commit_get(commit);
+ spin_unlock(&crtc->commit_lock);
+
+ if (!commit)
+ continue;
+
+ ret = wait_for_completion_timeout(&commit->hw_done,
+ 10*HZ);
+ if (ret == 0)
+ DRM_ERROR("[CRTC:%d:%s] hw_done timed out\n",
+ crtc->base.id, crtc->name);
+ drm_crtc_commit_put(commit);
+ }
+ }

for_each_connector_in_state(state, connector, conn_state, i) {
connector->state->state = state;
@@ -1575,6 +1878,15 @@ void drm_atomic_helper_swap_state(struct drm_atomic_state *state,
crtc->state->state = state;
swap(state->crtcs[i].state, crtc->state);
crtc->state->state = NULL;
+
+ if (state->crtcs[i].commit) {
+ spin_lock(&crtc->commit_lock);
+ list_add(&state->crtcs[i].commit->commit_entry,
+ &crtc->commit_list);
+ spin_unlock(&crtc->commit_lock);
+
+ state->crtcs[i].commit->event = NULL;
+ }
}

for_each_plane_in_state(state, plane, plane_state, i) {
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 88cf22052a69..3e52a6ecf6c0 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -669,6 +669,9 @@ int drm_crtc_init_with_planes(struct drm_device *dev, struct drm_crtc *crtc,
crtc->dev = dev;
crtc->funcs = funcs;

+ INIT_LIST_HEAD(&crtc->commit_list);
+ spin_lock_init(&crtc->commit_lock);
+
drm_modeset_lock_init(&crtc->mutex);
ret = drm_mode_object_get(dev, &crtc->base, DRM_MODE_OBJECT_CRTC);
if (ret)
diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index 4c4b30f7a9f2..5921b203503a 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -686,6 +686,12 @@ void drm_send_event_locked(struct drm_device *dev, struct drm_pending_event *e)
{
assert_spin_locked(&dev->event_lock);

+ if (e->completion) {
+ /* ->completion might disappear as soon as it signalled. */
+ complete_all(e->completion);
+ e->completion = NULL;
+ }
+
if (e->fence) {
fence_signal(e->fence);
fence_put(e->fence);
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 51f751d1c8a4..781db4f562d4 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -283,6 +283,7 @@ struct drm_ioctl_desc {

/* Event queued up for userspace to read */
struct drm_pending_event {
+ struct completion *completion;
struct drm_event *event;
struct fence *fence;
struct list_head link;
diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
index 465a1212f4f0..abec2a3f0225 100644
--- a/include/drm/drm_atomic.h
+++ b/include/drm/drm_atomic.h
@@ -30,6 +30,12 @@

#include <drm/drm_crtc.h>

+void drm_crtc_commit_put(struct drm_crtc_commit *commit);
+static inline void drm_crtc_commit_get(struct drm_crtc_commit *commit)
+{
+ kref_get(&commit->ref);
+}
+
struct drm_atomic_state * __must_check
drm_atomic_state_alloc(struct drm_device *dev);
void drm_atomic_state_clear(struct drm_atomic_state *state);
diff --git a/include/drm/drm_atomic_helper.h b/include/drm/drm_atomic_helper.h
index 0276447225ed..5fb8c306e16b 100644
--- a/include/drm/drm_atomic_helper.h
+++ b/include/drm/drm_atomic_helper.h
@@ -38,6 +38,7 @@ int drm_atomic_helper_check_planes(struct drm_device *dev,
struct drm_atomic_state *state);
int drm_atomic_helper_check(struct drm_device *dev,
struct drm_atomic_state *state);
+void drm_atomic_helper_commit_tail(struct drm_atomic_state *state);
int drm_atomic_helper_commit(struct drm_device *dev,
struct drm_atomic_state *state,
bool nonblock);
@@ -74,6 +75,13 @@ void drm_atomic_helper_disable_planes_on_crtc(struct drm_crtc *crtc,
void drm_atomic_helper_swap_state(struct drm_atomic_state *state,
bool stall);

+/* nonblocking commit helpers */
+int drm_atomic_helper_setup_commit(struct drm_atomic_state *state,
+ bool nonblock);
+void drm_atomic_helper_wait_for_dependencies(struct drm_atomic_state *state);
+void drm_atomic_helper_commit_hw_done(struct drm_atomic_state *state);
+void drm_atomic_helper_commit_cleanup_done(struct drm_atomic_state *state);
+
/* implementations for legacy interfaces */
int drm_atomic_helper_update_plane(struct drm_plane *plane,
struct drm_crtc *crtc,
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index d5d5e343531e..c0edd87fa0ee 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -725,9 +725,6 @@ struct drm_crtc_funcs {
* @gamma_store: gamma ramp values
* @helper_private: mid-layer private data
* @properties: property tracking for this CRTC
- * @state: current atomic state for this CRTC
- * @acquire_ctx: per-CRTC implicit acquire context used by atomic drivers for
- * legacy IOCTLs
*
* Each CRTC may have one or more connectors associated with it. This structure
* allows the CRTC to be controlled.
@@ -780,11 +777,37 @@ struct drm_crtc {

struct drm_object_properties properties;

+ /**
+ * @state:
+ *
+ * Current atomic state for this CRTC.
+ */
struct drm_crtc_state *state;

- /*
- * For legacy crtc IOCTLs so that atomic drivers can get at the locking
- * acquire context.
+ /**
+ * @commit_list:
+ *
+ * List of &drm_crtc_commit structures tracking pending commits.
+ * Protected by @commit_lock. This list doesn't hold its own full
+ * reference, but burrows it from the ongoing commit. Commit entries
+ * must be removed from this list once the commit is fully completed,
+ * but before it's correspoding &drm_atomic_state gets destroyed.
+ */
+ struct list_head commit_list;
+
+ /**
+ * @commit_lock:
+ *
+ * Spinlock to protect @commit_list.
+ */
+ spinlock_t commit_lock;
+
+ /**
+ * @acquire_ctx:
+ *
+ * Per-CRTC implicit acquire context used by atomic drivers for legacy
+ * IOCTLs, so that atomic drivers can get at the locking acquire
+ * context.
*/
struct drm_modeset_acquire_ctx *acquire_ctx;
};
@@ -1694,6 +1717,78 @@ struct drm_bridge {
void *driver_private;
};

+/**
+ * struct drm_crtc_commit - track modeset commits on a CRTC
+ */
+struct drm_crtc_commit {
+ /**
+ * @crtc:
+ *
+ * DRM CRTC for this commit.
+ */
+ struct drm_crtc *crtc;
+
+ /**
+ * @ref:
+ *
+ * Reference count for this structure. Needed to allow blocking on
+ * completions without the risk of the completion disappearing
+ * meanwhile.
+ */
+ struct kref ref;
+
+ /**
+ * @flip_done:
+ *
+ * Will be signaled when the hardware has flipped to the new set of
+ * buffers. Signals at the same time as when the drm event for this
+ * commit is sent to userspace, or when an out-fence is singalled. Note
+ * that for most hardware, in most cases this happens after @hw_done is
+ * signalled.
+ */
+ struct completion flip_done;
+
+ /**
+ * @hw_done:
+ *
+ * Will be signalled when all hw register changes for this commit have
+ * been written out. Especially when disabling a pipe this can be much
+ * later than than @flip_done, since that can signal already when the
+ * screen goes black, whereas to fully shut down a pipe more register
+ * I/O is required.
+ *
+ * Note that this does not need to include separately reference-counted
+ * resources like backing storage buffer pinning, or runtime pm
+ * management.
+ */
+ struct completion hw_done;
+
+ /**
+ * cleanup_done:
+ *
+ * Will be signalled after old buffers have been cleaned up again by
+ * calling drm_atomic_helper_cleanup_planes(). Since this can only
+ * happen after a vblank wait completed it might be a bit later. This
+ * completion is useful to throttle updates and avoid hardware updates
+ * getting ahead of the buffer cleanup too much.
+ */
+ struct completion cleanup_done;
+
+ /**
+ * @commit_entry:
+ *
+ * Entry on the per-CRTC commit_list. Protected by crtc->commit_lock.
+ */
+ struct list_head commit_entry;
+
+ /**
+ * @event:
+ *
+ * &drm_pending_vblank_event pointer to clean up private events.
+ */
+ struct drm_pending_vblank_event *event;
+};
+
struct __drm_planes_state {
struct drm_plane *ptr;
struct drm_plane_state *state;
@@ -1702,6 +1797,7 @@ struct __drm_planes_state {
struct __drm_crtcs_state {
struct drm_crtc *ptr;
struct drm_crtc_state *state;
+ struct drm_crtc_commit *commit;
};

struct __drm_connnectors_state {
@@ -1733,6 +1829,14 @@ struct drm_atomic_state {
struct __drm_connnectors_state *connectors;

struct drm_modeset_acquire_ctx *acquire_ctx;
+
+ /**
+ * @commit_work:
+ *
+ * Work item which can be used by the driver or helpers to execute the
+ * commit without blocking.
+ */
+ struct work_struct commit_work;
};

@@ -2074,6 +2178,7 @@ struct drm_mode_config_funcs {
* @async_page_flip: does this device support async flips on the primary plane?
* @cursor_width: hint to userspace for max cursor width
* @cursor_height: hint to userspace for max cursor height
+ * @helper_private: mid-layer private data
*
* Core mode resource tracking structure. All CRTC, encoders, and connectors
* enumerated by the driver are added here, as are global properties. Some
@@ -2193,6 +2298,8 @@ struct drm_mode_config {

/* cursor size */
uint32_t cursor_width, cursor_height;
+
+ struct drm_mode_config_helper_funcs *helper_private;
};

/**
diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h
index d4619dc2eecb..145c147705d8 100644
--- a/include/drm/drm_modeset_helper_vtables.h
+++ b/include/drm/drm_modeset_helper_vtables.h
@@ -925,4 +925,40 @@ static inline void drm_plane_helper_add(struct drm_plane *plane,
plane->helper_private = funcs;
}

+/**
+ * struct drm_mode_config_helper_funcs - global modeset helper operations
+ *
+ * These helper functions are used by the atomic helpers.
+ */
+struct drm_mode_config_helper_funcs {
+ /**
+ * @atomic_commit_tail:
+ *
+ * This hook should commit the given atomic state to the hardware, but
+ * nothing else. This excludes specifically any prepare and cleanup work
+ * done by drm_atomic_helper_prepare_planes() and
+ * drm_atomic_helper_cleanup_planes(). And also any synchronization and
+ * stalling necessary around the around the hardware commit as done for
+ * example by drm_atomic_helper_wait_for_fences() or
+ * drm_atomic_helper_wait_for_vblanks().
+ *
+ * The function is not required to stall for the commit to actually
+ * complete and for the new buffers to be displayed on the screen. This
+ * is handled by properly signalling the &drm_pending_vblank_event in each
+ * &drm_crtc_state through a call to drm_send_vblank_event() or
+ * drm_arm_vblank_event(), depending upon how the driver works.
+ *
+ * When disabling a CRTC otoh this hook _must_ stall for the commit to
+ * complete. Vblank waits don't work on disabled CRTC, hence the core
+ * can't take care of this. And it also can't rely on the vblank event,
+ * since that can be signalled already when the screen shows black,
+ * which can happen much earlier than the last hardware access needed to
+ * shut off the display pipeline completely.
+ *
+ * This hook is optional, the default implementation is
+ * drm_atomic_helper_commit_tail().
+ */
+ void (*atomic_commit_tail)(struct drm_atomic_state *state);
+};
+
#endif
--
2.8.1

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