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| author | Michel Dänzer <michel.daenzer@amd.com> | 2015-05-26 11:53:38 +0300 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2015-05-27 14:00:08 +0300 |
| commit | 5ceecb2fa720c01a97e6fa2353c2b8f1e8d69f1f (patch) | |
| tree | 4a9ad864ed2ff736c7138fa997875b7944601d6e /drivers/gpu/drm/drm_irq.c | |
| parent | 60f207a5b6d8f23c2e8388b415e8d5c7311cc79d (diff) | |
| download | linux-5ceecb2fa720c01a97e6fa2353c2b8f1e8d69f1f.tar.xz | |
drm: Fix off-by-one in vblank hardware counter wraparound handling
dev->max_vblank_count contains the largest value that can be represented
by the hardware counter. When the hardware counter wraps around, we have
to add that value + 1 to get the same value as if the hardware counter
didn't wrap around.
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Diffstat (limited to 'drivers/gpu/drm/drm_irq.c')
| -rw-r--r-- | 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 1967e7fc9805..6f02b4b560b8 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -130,7 +130,7 @@ static void drm_update_vblank_count(struct drm_device *dev, int crtc) /* * Interrupts were disabled prior to this call, so deal with counter * wrap if needed. - * NOTE! It's possible we lost a full dev->max_vblank_count events + * NOTE! It's possible we lost a full dev->max_vblank_count + 1 events * here if the register is small or we had vblank interrupts off for * a long time. * @@ -147,7 +147,7 @@ static void drm_update_vblank_count(struct drm_device *dev, int crtc) /* Deal with counter wrap */ diff = cur_vblank - vblank->last; if (cur_vblank < vblank->last) { - diff += dev->max_vblank_count; + diff += dev->max_vblank_count + 1; DRM_DEBUG("last_vblank[%d]=0x%x, cur_vblank=0x%x => diff=0x%x\n", crtc, vblank->last, cur_vblank, diff); |