[PATCH] drm/nouveau: Fix pre-nv50 pageflip events (v2)

[Mario Kleiner]

On 11/09/2015 02:02 PM, Ilia Mirkin wrote:
> On Mon, Nov 9, 2015 at 7:57 AM, Mario Kleiner
> <mario.kleiner.de at gmail.com> wrote:
>> From: Daniel Vetter <daniel.vetter at ffwll.ch>
>>
>> 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 at gmail.com>
>> 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 at nvidia.com>
>> 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.
>>
>> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=106431
>> Cc: Thierry Reding <treding at nvidia.com>
>> Cc: Mario Kleiner <mario.kleiner.de at gmail.com>
>> Cc: Ben Skeggs <bskeggs at redhat.com>
>> Cc: Ilia Mirkin <imirkin at alum.mit.edu>
>>
>> v2 (mario): Integrate my own review comments into Daniels patch.
>>     - Fix function prototypes in drmP.h
>>     - Add missing vblank_put() for pageflip completion without
>>       pageflip event.
>>     - Initialize sequence number for queued pageflip event to avoid
>>       trouble in drm_handle_vblank_events().
>>     - Remove dead code and spelling fix.
>>
>> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
>> Reviewed-by: Mario Kleiner <mario.kleiner.de at gmail.com>
>
> Without commenting on the actual patch, a few points of procedure:
>
> (a) If you're sending the patch, you're supposed to add your
> Signed-off-by. So you'd keep Daniel's and add yours.

I thought my tiny fixes didn't warrant adding a signed off by myself, 
but if that was wrong, consider it added:

v2: Signed-off-by: Mario Kleiner <mario.kleiner.de at gmail.com>

> (b) Since this is triggering warns for real people in real situations,
> tack on a
>
> Cc: stable at vger.kernel.org # v4.3
>

Ah, sorry, this is already a problem in a released kernel? I thought 
this was something new and so far only for drm-next.

ciao,
-mario

> Cheers,
>
>    -ilia
>