Use of abs() wrongly wrapped diff_ns to 32 bit, which gives a 1/4000
probability of a missed vblank increment at each vblank irq reenable
if the kms driver doesn't support high precision vblank timestamping.
Not a big deal in practice, but let's make it nice.
Signed-off-by: Mario Kleiner <mario.klei...@tuebingen.mpg.de>
---
drivers/gpu/drm/drm_irq.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 0054e95..149805a 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -164,7 +164,7 @@ static void vblank_disable_and_save(struct drm_device *dev,
int crtc)
* available. In that case we can't account for this and just
* hope for the best.
*/
- if ((vblrc > 0) && (abs(diff_ns) > 1000000))
+ if ((vblrc > 0) && (abs64(diff_ns) > 1000000))
atomic_inc(&dev->_vblank_count[crtc]);
/* Invalidate all timestamps while vblank irq's are off. */
@@ -1293,7 +1293,7 @@ void drm_handle_vblank(struct drm_device *dev, int crtc)
* e.g., due to spurious vblank interrupts. We need to
* ignore those for accounting.
*/
- if (abs(diff_ns) > DRM_REDUNDANT_VBLIRQ_THRESH_NS) {
+ if (abs64(diff_ns) > DRM_REDUNDANT_VBLIRQ_THRESH_NS) {
/* Store new timestamp in ringbuffer. */
vblanktimestamp(dev, crtc, vblcount + 1) = tvblank;
smp_wmb();
--
1.7.1
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