Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit c4cc3839 authored by Mario Kleiner's avatar Mario Kleiner Committed by Dave Airlie
Browse files

drm/vblank: Use abs64(diff_ns) for s64 diff_ns instead of abs(diff_ns) 



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: default avatarMario Kleiner <mario.kleiner@tuebingen.mpg.de>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
parent e40b6fc8

drivers/gpu/drm/drm_irq.c

+2 −2
Original line number Diff line number Diff line
@@ -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 @@ bool 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();