On 10.06.2016 23:43, Daniel Vetter wrote: > On Fri, Jun 10, 2016 at 05:57:12PM +0900, Michel Dänzer wrote: >> From: Michel Dänzer <michel.daenzer@xxxxxxx> >> >> If userspace wants a page flip to take effect during vblank sequence n, >> it has to wait for vblank seqno n-1 before calling the >> DRM_IOCTL_MODE_PAGE_FLIP ioctl. >> >> This change makes sure that we do not program the flip to the hardware >> before the end of vblank seqno n-1 in this case, to prevent the flip >> from taking effect too early. >> >> On the other hand, if the DRM_IOCTL_MODE_PAGE_FLIP ioctl is called >> during vblank, but userspace didn't wait for the current vblank seqno >> before, this change would still allow the flip to be programmed during >> the current vblank seqno. > > This just sounds like you're sending vblank events out a bit too early. > And watching vblank waits that userspace does works, but it's fragile, > add-hoc and I don't really jump in joy about adding that to the vblank > core. Is there no way you can adjust sending out the vblank events > similarly, to make sure userspace can never sneak in a pageflip too early? What you call "too early" is actually "during the vertical blank period waited for". IMHO only notifying userspace of a vertical blank period when it's already over would defeat the purpose. -- Earthling Michel Dänzer | http://www.amd.com Libre software enthusiast | Mesa and X developer _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
