From c50d7521617d823d769b280bc499e19e364434ae Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ville=20Syrj=C3=A4l=C3=A4?= Date: Wed, 6 Aug 2014 14:49:59 +0300 Subject: [PATCH] drm: Store the vblank timestamp when adjusting the counter during disable MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit During vblank disable the code tries to guess based on the timestamps whether we just missed one vblank or not. And if so it increments the counter. However it forgets to store the new timestamp to the approriate slot in our timestamp ring buffer. So anyone querying the timestamp for the resulting sequence number would get a stale timestamp. Fix it up by storing the new timestamp. Signed-off-by: Ville Syrjälä Signed-off-by: Daniel Vetter --- drivers/gpu/drm/drm_irq.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index 62dee812d28a..aa9b06495067 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -198,6 +198,13 @@ static void vblank_disable_and_save(struct drm_device *dev, int crtc) * hope for the best. */ if ((vblrc > 0) && (abs64(diff_ns) > 1000000)) { + /* Store new timestamp in ringbuffer. */ + vblanktimestamp(dev, crtc, vblcount + 1) = tvblank; + + /* Increment cooked vblank count. This also atomically commits + * the timestamp computed above. + */ + smp_mb__before_atomic(); atomic_inc(&vblank->count); smp_mb__after_atomic(); } -- 2.20.1