When we are at it, the one with the title "[PATCH] drm/nouveau: Use
drm_vblank_on/off consistently" from Daniel, which has a reviewed and
tested by me also never made it into nouveau.
Maybe pick that up as well?
-mario
On 12/01/2015 04:55 PM, Daniel Vetter wrote:
On Tue, Dec 01, 2015 at 04:08:16PM +0100, poma wrote:
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
Ben Skeggs asleep probably. Dave, can you pls pick this up?
-Daniel
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