On Wed, Aug 30, 2017 at 02:17:49PM +0200, Maarten Lankhorst wrote:
When commit synchronization through drm_crtc_commit was first introduced, we tried to solve the problem of the flip_done needing a reference count by blocking in cleanup_done.
This has been changed by commit 24835e442f28 ("drm: reference count event->completion") which made the waits here no longer needed.
This is wrong. Your next patch makes this no longer necessary.
Signed-off-by: Maarten Lankhorst maarten.lankhorst@linux.intel.com Suggested-by: Daniel Vetter daniel.vetter@ffwll.ch
drivers/gpu/drm/drm_atomic_helper.c | 17 ----------------- 1 file changed, 17 deletions(-)
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index 4e53aae9a1fb..11d0e94a2181 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -1885,7 +1885,6 @@ void drm_atomic_helper_commit_cleanup_done(struct drm_atomic_state *old_state) struct drm_crtc_state *new_crtc_state; struct drm_crtc_commit *commit; int i;
long ret;
for_each_new_crtc_in_state(old_state, crtc, new_crtc_state, i) { commit = old_state->crtcs[i].commit;
@@ -1895,22 +1894,6 @@ void drm_atomic_helper_commit_cleanup_done(struct drm_atomic_state *old_state) 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. */
This comment here is the clue: "... otherwise subsequent commits wont stall properly". When we remove the drm_crtc_commit from commit_list, the next commit won't be able to properly stall for flip_done. Hence we must wait for flip_done before removing it.
But with your new patch we wait for flip_done using old_crtc_state->commit, and this is indeed no longer necessary.
With the commit message and patch ordering fixed up:
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
if (try_wait_for_completion(&commit->flip_done))goto del_commit;/* 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);-del_commit: spin_lock(&crtc->commit_lock); list_del(&commit->commit_entry); spin_unlock(&crtc->commit_lock); -- 2.11.0
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