Hi Mark,
On 02/12/2021 16:11, Mark Yacoub wrote:
From: Mark Yacoub <markyacoub@xxxxxxxxxx>
please make sure to add the linux-mediatek mailinglist in any follow-up
communication.
Regards,
Matthias
[Why]
drm_handle_vblank_events loops over vblank_event_list to send any event
that is current or has passed.
More than 1 event could be pending with past sequence time that need to
be send. This can be a side effect of drivers without hardware vblank
counter and they depend on the difference in the timestamps and the
frame/field duration calculated in drm_update_vblank_count. This can
lead to 1 vblirq being ignored due to very small diff, resulting in a
subsequent vblank with 2 pending vblank events to be sent, each with a
unique sequence expected by user space.
[How]
Send each pending vblank event with the sequence it's waiting on instead
of assigning the current sequence to all of them.
Fixes igt@kms_flip "Unexpected frame sequence"
Tested on Jacuzzi (MT8183)
Signed-off-by: Mark Yacoub <markyacoub@xxxxxxxxxxxx>
---
drivers/gpu/drm/drm_vblank.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 3417e1ac79185..47da8056abc14 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -1902,7 +1902,7 @@ static void drm_handle_vblank_events(struct drm_device *dev, unsigned int pipe)
list_del(&e->base.link);
drm_vblank_put(dev, pipe);
- send_vblank_event(dev, e, seq, now);
+ send_vblank_event(dev, e, e->sequence, now);
}
if (crtc && crtc->funcs->get_vblank_timestamp)
