diff options
| -rw-r--r-- | drivers/gpu/drm/drm_irq.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index 87d148cec877..ad699b729278 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -148,8 +148,15 @@ static void vblank_disable_and_save(struct drm_device *dev, int crtc) * has been ticking all along until this time. This makes the * count account for the entire time between drm_vblank_on() and * drm_vblank_off(). + * + * But only do this if precise vblank timestamps are available. + * Otherwise we might read a totally bogus timestamp since drivers + * lacking precise timestamp support rely upon sampling the system clock + * at vblank interrupt time. Which obviously won't work out well if the + * vblank interrupt is disabled. */ - if (!vblank->enabled) { + if (!vblank->enabled && + drm_get_last_vbltimestamp(dev, crtc, &tvblank, 0) > 0) { drm_update_vblank_count(dev, crtc); spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags); return; |