On 2020-02-12 6:42 p.m., Carsten Haitzler wrote: > On Wed, 12 Feb 2020 16:45:50 +0100 Michel Dänzer <mic...@daenzer.net> said: > >> On 2020-02-12 4:34 p.m., Carsten Haitzler wrote: >>> On Wed, 12 Feb 2020 15:36:06 +0100 Michel Dänzer <mic...@daenzer.net> said: >>> >>>> On 2020-02-12 2:06 p.m., Carsten Haitzler wrote: >>>>> On Wed, 12 Feb 2020 13:23:28 +0200 Pekka Paalanen <ppaala...@gmail.com> >>>>> said: >>>>> >>>>>> On Wed, 12 Feb 2020 11:07:56 +0000 >>>>>> Carsten Haitzler <ras...@rasterman.com> wrote: >>>>>> >>>>>>> On Wed, 12 Feb 2020 12:40:15 +0200 Pekka Paalanen <ppaala...@gmail.com> >>>>>>> said: >>>>>>> >>>>>>>> On Wed, 12 Feb 2020 10:21:02 +0000 >>>>>>>> Carsten Haitzler (The Rasterman) <ras...@rasterman.com> wrote: >>>>>>>> >>>>>>>>> even better - if the /dev/dri/card0 >>>>>>>>> device exists, dlopen libdrm and get some symbols from it and ... use >>>>>>>>> it to request the drm device sent you vsync events so you can use the >>>>>>>>> vsync interrupt as your frame event. this will be another fd to listen >>>>>>>>> on in select() and of course you can turn this vblank event stream on >>>>>>>>> and off. >>>>>>>> >>>>>>>> Please don't. Talk to the X server instead. >>>>>>> >>>>>>> and what vsync events does the xserver provide? >>>>>> >>>>>> You don't want vsync events. You have no idea what they >>>>>> correspond to, or even if you opened the right device. >>>>>> >>>>>> https://gitlab.freedesktop.org/xorg/proto/xorgproto/blob/master/presentproto.txt >>>>> >>>>> I wrote the drm support before the present extension existed. The drm >>>>> path is easy to support - only open if a single card exists (if multiple >>>>> - don't do it and fall back to timer based animation) and you can filter >>>>> for multiple screens as you get events for all screens. Yes - you end up >>>>> syncing with a single chosen screen if you filter for just one of the >>>>> vblank events, but it's better than using the system clock. >>>> >>>> You only get an event for the CRTC you ask for in the >>>> DRM_IOCTL_WAIT_VBLANK ioctl. How do yo know which CRTC to pick? >>> >>> drmVBlank vbl; >>> vbl.request.type = DRM_VBLANK_RELATIVE | DRM_VBLANK_EVENT; >>> vbl.request.sequence = 1; >>> vbl.request.signal = 0; >>> drmWaitVBlank(drm_fd, &vbl); >>> >>> has worked a charm for maybe give or take close to a decade (as i said - >>> before present existed). >> >> That selects the first CRTC. It'll work most of the time, except when >> the first CRTC isn't enabled for some reason. > > I've seen it select multiple crtc's as I get multiple vblank events with the > same frame number... (thus filter out the dups to only get one).
Sounds like something's wrong. Try setting vbl.request.signal to a unique (e.g. monotonically increasing) value for each drmWaitVBlank call. The value is replicated in the user_data field of the corresponding event. If you get multiple events with the same user_data value, that indicates a kernel bug. -- Earthling Michel Dänzer | https://redhat.com Libre software enthusiast | Mesa and X developer _______________________________________________ xorg-devel@lists.x.org: X.Org development Archives: http://lists.x.org/archives/xorg-devel Info: https://lists.x.org/mailman/listinfo/xorg-devel
