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[04/11] drm/komeda: Annotate dma-fence critical section in commit path

Message ID 20210121152959.1725404-5-daniel.vetter@ffwll.ch (mailing list archive)
State New, archived
Headers show
Series dma_fence critical sections annotations for atomic | expand

Commit Message

Daniel Vetter Jan. 21, 2021, 3:29 p.m. UTC
Like the helpers, nothing special. Well except not, because we the
critical section extends until after hw_done(), since that's the last
thing which could hold up a subsequent atomic commit. That means the
wait_for_flip_done is included, but that's not a problem, we're
allowed to call dma_fence_wait() from signalling critical sections.
Even on our own fence (which this does), it's just a bit confusing.
But in a way those last 2 function calls are already part of the fence
signalling critical section for the next atomic commit.

Reading this I'm wondering why komeda waits for flip_done() before
calling hw_done(), which is a bit backwards (but hey hw can be
special). Might be good to throw a comment in there that explains why,
because the original commit that added this just doesn't.

v2: Small rebase

Reviewed-by: James Qian Wang <james.qian.wang@arm.com> (v1)
Cc: "James (Qian) Wang" <james.qian.wang@arm.com>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Mihail Atanassov <mihail.atanassov@arm.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
 drivers/gpu/drm/arm/display/komeda/komeda_kms.c | 3 +++
 1 file changed, 3 insertions(+)
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diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_kms.c b/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
index 034ee08482e0..aeda4e5ec4f4 100644
--- a/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
@@ -73,6 +73,7 @@  static const struct drm_driver komeda_kms_driver = {
 static void komeda_kms_commit_tail(struct drm_atomic_state *old_state)
 	struct drm_device *dev = old_state->dev;
+	bool fence_cookie = dma_fence_begin_signalling();
 	drm_atomic_helper_commit_modeset_disables(dev, old_state);
@@ -85,6 +86,8 @@  static void komeda_kms_commit_tail(struct drm_atomic_state *old_state)
 	drm_atomic_helper_wait_for_flip_done(dev, old_state);
+	dma_fence_end_signalling(fence_cookie);
 	drm_atomic_helper_cleanup_planes(dev, old_state);