From: Ville Syrjälä ville.syrjala@linux.intel.com

If we couldn't get a high precisions vblank timestamp, we currently store a zeroed timestamp instead and assume the next vblank irq to get us something better. This makes sense when trying to update the timestamp from eg. vblank enable. But if we do this from the vblank irq we will never get a vblank timestamp unless we high precision timestamps are available and succeeded. This break weston for instance on drivers lacking high precision timestamps.

To fix this, zero the timestamp only when not called from vbl irq. When called from the irq, we still want the timestamp, even if not perfect.

This fixes a regression from 4dfd64862ff852df drm: Use vblank timestamps to guesstimate how many vblanks were missed

Cc: Mario Kleiner mario.kleiner.de@gmail.com Cc: Thierry Reding thierry.reding@gmail.com Reported-by: Thierry Reding thierry.reding@gmail.com Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com --- drivers/gpu/drm/drm_irq.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index f24c57c..1b9faa0 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -232,10 +232,11 @@ static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe,

/* * Only reinitialize corresponding vblank timestamp if high-precision query - * available and didn't fail. Otherwise reinitialize delayed at next vblank - * interrupt and assign 0 for now, to mark the vblanktimestamp as invalid. + * available and didn't fail, or we were called from the vblank interrupt. + * Otherwise reinitialize delayed at next vblank interrupt and assign 0 + * for now, to mark the vblanktimestamp as invalid. */ - if (!rc) + if (!rc && (flags & DRM_CALLED_FROM_VBLIRQ) == 0) t_vblank = (struct timeval) {0, 0};

store_vblank(dev, pipe, diff, &t_vblank, cur_vblank);