> > 4. Do I need to wait for vblank for modesetting? I know it will be an > > error if I tried to do drmModePageFlip before the last one is handled > > but what about drmModeSetCrtc? Do I need to wait for a vblank for the > > last pageflip? > > Right now, if you don't wait for any pending page flip to complete before > drmModeSetCrtc, the two may race, and the CRTC may end up scanning out from the FB set by the page flip. > > Maybe this race should be prevented in the kernel though. Maybe this could happen on non-atomic drivers, but on atomic drivers there's no race, the setcrtc will wait for the previous pageflip to complete first. Ofc if you call both from 2 threads at the same time then either could win, but if you do one after the other there's no ordering issues with atomic drivers. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
