On Fri, Jun 30, 2017 at 5:26 PM, Daniel Vetter <daniel@xxxxxxxx> wrote: > On Fri, Jun 30, 2017 at 05:18:41PM +0300, ville.syrjala@xxxxxxxxxxxxxxx wrote: >> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> >> >> Add drm_crtc_vblank_get_accurate() which is the same as >> drm_crtc_vblank_get() except that it will forcefully update the >> the current vblank counter/timestamp value even if the interrupt >> is already enabled. >> >> And we'll switch drm_wait_one_vblank() over to using it to make sure it >> will really wait at least one vblank even if it races with the irq >> handler. >> >> Cc: Daniel Vetter <daniel@xxxxxxxx> >> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > > Hm, I just thought of doing an > s/drm_vblank_count/drm_crtc_accurate_vblank_count/ in > drm_crtc_arm_vblank_event. > > What does this buy us above&beyond the other patch? And why isn't > vblank_get accurate always? This also seems to have the risk of not fixing the arm_vblank_event race if someone puts the vblank_get_accurate outside of the critical section. Then we're back to the same old race. And since that means you need to have a vblank_get_accurate right before the arm_vblank_event in all cases, we might as well just put it into the helper. You wrote in the other thread putting it into arm_vblank_event might be wasteful, but I don't see any scenario where that could be the case ... Or do I miss something? -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
