To facilitate easier reviewing this is split out from the overall nonblocking commit rework. It just rolls out the helper functions and uses them in the main drm_atomic_helper_commit() function to make it clear where in the flow they're used.
The next patch will actually split drm_atomic_helper_commit() into 2 pieces, with the tail being run asynchronously from a worker.
v2: Improve kerneldocs (Maarten).
v3: Don't convert ERESTARTSYS to EINTR (Maarten). Also don't fail if the wait succeed in stall_check - we need to convert that case (it returns the remaining jiffies) to 0 for success.
Tested-by: Tomeu Vizoso tomeu.vizoso@collabora.com Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Cc: Tomeu Vizoso tomeu.vizoso@gmail.com Cc: Daniel Stone daniels@collabora.com Tested-by: Liviu Dudau Liviu.Dudau@arm.com Signed-off-by: Daniel Vetter daniel.vetter@intel.com --- drivers/gpu/drm/drm_atomic_helper.c | 346 ++++++++++++++++++++++++++++++++++++ include/drm/drm_atomic_helper.h | 7 + 2 files changed, 353 insertions(+)
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index 326ee34cdba4..63e46827b303 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -1155,6 +1155,10 @@ int drm_atomic_helper_commit(struct drm_device *dev, if (nonblock) return -EBUSY;
+ ret = drm_atomic_helper_setup_commit(state, nonblock); + if (ret) + return ret; + ret = drm_atomic_helper_prepare_planes(dev, state); if (ret) return ret; @@ -1185,16 +1189,22 @@ int drm_atomic_helper_commit(struct drm_device *dev,
drm_atomic_helper_wait_for_fences(dev, state);
+ drm_atomic_helper_wait_for_dependencies(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_commit_hw_done(state); + drm_atomic_helper_wait_for_vblanks(dev, state);
drm_atomic_helper_cleanup_planes(dev, state);
+ drm_atomic_helper_commit_cleanup_done(state); + drm_atomic_state_free(state);
return 0; @@ -1239,6 +1249,305 @@ 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); + + drm_crtc_commit_put(stall_commit); + + return ret < 0 ? ret : 0; +} + +/** + * drm_atomic_helper_setup_commit - setup possibly nonblocking commit + * @state: new modeset state to be committed + * @nonblock: whether nonblocking behavior is requested. + * + * This function prepares @state to be used by the atomic helper's support for + * nonblocking commits. Drivers using the nonblocking commit infrastructure + * should always call this function from their ->atomic_commit hook. + * + * To be able to use this support drivers need to use a few more helper + * functions. drm_atomic_helper_wait_for_dependencies() must be called before + * actually committing the hardware state, and for nonblocking commits this call + * must be placed in the async worker. See also drm_atomic_helper_swap_state() + * and it's stall parameter, for when a driver's commit hooks look at the + * ->state pointers of struct &drm_crtc, &drm_plane or &drm_connector directly. + * + * Completion of the hardware commit step must be signalled using + * drm_atomic_helper_commit_hw_done(). After this step the driver is not allowed + * to read or change any permanent software or hardware modeset state. The only + * exception is state protected by other means than &drm_modeset_lock locks. + * Only the free standing @state with pointers to the old state structures can + * be inspected, e.g. to clean up old buffers using + * drm_atomic_helper_cleanup_planes(). + * + * At the very end, before cleaning up @state drivers must call + * drm_atomic_helper_commit_cleanup_done(). + * + * This is all implemented by in drm_atomic_helper_commit(), giving drivers a + * complete and esay-to-use default implementation of the atomic_commit() hook. + * + * The tracking of asynchronously executed and still pending commits is done + * using the core structure &drm_crtc_commit. + * + * By default there's no need to clean up resources allocated by this function + * explicitly: drm_atomic_state_default_clear() will take care of that + * automatically. + * + * 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; +} + +/** + * drm_atomic_helper_wait_for_dependencies - wait for required preceeding commits + * @state: new modeset state to be committed + * + * This function waits for all preceeding commits that touch the same CRTC as + * @state to both be committed to the hardware (as signalled by + * drm_atomic_Helper_commit_hw_done) and executed by the hardware (as signalled + * by calling drm_crtc_vblank_send_event on the event member of + * &drm_crtc_state). + * + * This is part of the atomic helper support for nonblocking commits, see + * drm_atomic_helper_setup_commit() for an overview. + */ +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); + +/** + * drm_atomic_helper_commit_hw_done - setup possible nonblocking commit + * @state: new modeset state to be committed + * + * This function is used to signal completion of the hardware commit step. After + * this step the driver is not allowed to read or change any permanent software + * or hardware modeset state. The only exception is state protected by other + * means than &drm_modeset_lock locks. + * + * Drivers should try to postpone any expensive or delayed cleanup work after + * this function is called. + * + * This is part of the atomic helper support for nonblocking commits, see + * drm_atomic_helper_setup_commit() for an overview. + */ +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); + +/** + * drm_atomic_helper_commit_cleanup_done - signal completion of commit + * @state: new modeset state to be committed + * + * This signals completion of the atomic update @state, including any cleanup + * work. If used, it must be called right before calling + * drm_atomic_state_free(). + * + * This is part of the atomic helper support for nonblocking commits, see + * drm_atomic_helper_setup_commit() for an overview. + */ +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 (WARN_ON(!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. But only after it actually + * completed, otherwise subsequent commits won't stall properly. */ + if (try_wait_for_completion(&commit->flip_done)) { + list_del(&commit->commit_entry); + spin_unlock(&crtc->commit_lock); + continue; + } + + 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); + + spin_lock(&crtc->commit_lock); + list_del(&commit->commit_entry); + spin_unlock(&crtc->commit_lock); + } +} +EXPORT_SYMBOL(drm_atomic_helper_commit_cleanup_done); + /** * drm_atomic_helper_prepare_planes - prepare plane resources before commit * @dev: DRM device @@ -1558,17 +1867,45 @@ 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 = list_first_entry_or_null(&crtc->commit_list, + struct drm_crtc_commit, commit_entry); + 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; @@ -1580,6 +1917,15 @@ 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/include/drm/drm_atomic_helper.h b/include/drm/drm_atomic_helper.h index 07ede3a82d54..368cbffc54ac 100644 --- a/include/drm/drm_atomic_helper.h +++ b/include/drm/drm_atomic_helper.h @@ -74,6 +74,13 @@ 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,