On Mon, Nov 16, 2015 at 4:11 PM, Daniel Vetter <daniel@xxxxxxxx> wrote: > On Mon, Nov 02, 2015 at 04:45:00PM +0900, Michel Dänzer wrote: >> On 31.10.2015 06:55, Daniel Vetter wrote: >> > Apparently pre-nv50 pageflip events happen before the actual vblank >> > period. Therefore that functionality got semi-disabled in >> > >> > commit af4870e406126b7ac0ae7c7ce5751f25ebe60f28 >> > Author: Mario Kleiner <mario.kleiner.de@xxxxxxxxx> >> > Date: Tue May 13 00:42:08 2014 +0200 >> > >> > drm/nouveau/kms/nv04-nv40: fix pageflip events via special case. >> > >> > Unfortunately that hack got uprooted in >> > >> > commit cc1ef118fc099295ae6aabbacc8af94d8d8885eb >> > Author: Thierry Reding <treding@xxxxxxxxxx> >> > Date: Wed Aug 12 17:00:31 2015 +0200 >> > >> > drm/irq: Make pipe unsigned and name consistent >> > >> > Trigering a warning when trying to sample the vblank timestamp for a >> > non-existing pipe. There's a few ways to fix this: >> > >> > - Open-code the old behaviour, which just enshrines this slight >> > breakage of the userspace ABI. >> > >> > - Revert Mario's commit and again inflict broken timestamps, again not >> > pretty. >> > >> > - Fix this for real by delaying the pageflip TS until the next vblank >> > interrupt, thereby making it accurate. >> > >> > This patch implements the third option. Since having a page flip >> > interrupt that happens when the pageflip gets armed and not when it >> > completes in the next vblank seems to be fairly common (older i915 hw >> > works very similarly) create a new helper to arm vblank events for >> > such drivers. >> >> What happens when the page flip interrupt arrives during a vertical >> blank period? Presumably the userspace event will be deferred until the >> next vertical blank period, but the flip might already take effect in >> the current one. > > Hm yeah there's a tiny race if your update handler for the pageflip can > race with your vblank handler. That's impossible here since it's all done > from the same hw irq hanlder, and since that is single-threaded there > shouldn't be a problem, as long as vblank handling are pageflip are > ordered correctly. > > Might be worth a note in the kerneldoc though that this function isn't > perfectly foolproof. > -Daniel Is there any updates in this respect? drm-nouveau-Fix-pre-nv50-pageflip-events-v4.patch https://patchwork.kernel.org/patch/7591531 https://bugzilla.kernel.org/show_bug.cgi?id=106431 Reported: 2015-10-21 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
