Op 25-07-13 03:44, Keith Packard schreef: > Maarten Lankhorst <[email protected]> writes: > >> drm_calc_vbltimestamp_from_scanoutpos already uses CLOCK_MONOTONIC >> for the timestamps afaict. If you round to the nearest frame I don't see how >> you could >> possibly get glitches. > Because the display clock and the time clock are not slaved to each > other, so they will drift, possibly by quite a bit given the general > goal of using the cheapest components that meet the timing specs > everywhere. Plus, you'll presumably have NTP running, which will slew > even the monotonic clock rate around. > > You'd have to constantly update your notion of the expected time for > each frame or you'd be off from time to time. It's going to be wrong in the case where userspace relies on being able to convert from 1 to the other anyway in video applications, regardless of whether it happens in kernelspace or userspace, but this will not be the common case.
I just want the option of being able to specify an absolute time to synchronize to for the users, If opengl that wants to sync to a relative frame interval it can keep doing that. ~Maarten _______________________________________________ [email protected]: X.Org development Archives: http://lists.x.org/archives/xorg-devel Info: http://lists.x.org/mailman/listinfo/xorg-devel
