[PATCH 2/2] present: Fix use of vsynced pageflips and honor PresentOptionAsync. (v3)

[Eric Anholt]

Mario Kleiner <mario.kleiner.de at gmail.com> writes:

> Pageflips for Pixmap presents were not synchronized to vblank on
> drivers with support for PresentCapabilityAsync, due to some
> missing init for vblank->sync_flips. The PresentOptionAsync
> flag was completely ignored for pageflipped presents.
>
> Vsynced flips only worked by accident on the intel-ddx, as that
> driver doesn't have PresentCapabilityAsync support.
>
> On nouveau-ddx, which supports PresentCapabilityAsync, this
> always caused non-vsynced pageflips with pretty ugly tearing.
>
> This patch fixes the problem, as tested on top of XOrg 1.16.2
> on nouveau and intel.
>
> Please also apply to XOrg 1.17 and XOrg 1.16.2 stable.
>
> Applying on top of XOrg 1.16.2 may require cherry-picking
> commit 2051514652481a83bd7cf22e57cb0fcd40333f33
> which trivially fixes lack of support for protocol option
> PresentOptionCopy - get two bug fixes for the price of one!
>
> Signed-off-by: Mario Kleiner <mario.kleiner.de at gmail.com>
> ---
>  present/present.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/present/present.c b/present/present.c
> index e5d3fd5..be1c9f1 100644
> --- a/present/present.c
> +++ b/present/present.c
> @@ -834,7 +834,7 @@ present_pixmap(WindowPtr window,
>      vblank->notifies = notifies;
>      vblank->num_notifies = num_notifies;
>  
> -    if (!screen_priv->info || !(screen_priv->info->capabilities & PresentCapabilityAsync))
> +    if (!(options & PresentOptionAsync))
>          vblank->sync_flip = TRUE;

I think I'd like to see a hunk like this in with this patch, so that
each driver doesn't need to have the cap check:

diff --git a/present/present.c b/present/present.c
index a9f2214..ed0d734 100644
--- a/present/present.c
+++ b/present/present.c
@@ -838,6 +838,9 @@ present_pixmap(WindowPtr window,
         vblank->sync_flip = TRUE;
 
     if (!(options & PresentOptionCopy) &&
+        !((options & PresentOptionAsync) &&
+          (!screen_priv->info ||
+           !(screen_priv->info->capabilities & PresentCapabilityAsync))) &&
         pixmap != NULL &&
         present_check_flip (target_crtc, window, pixmap, vblank->sync_flip, valid, x_off, y_off))
     {

Seem reasonable?  If you wanted to squash this in, then this is:

Reviewed-by: Eric Anholt <eric at anholt.net>

(So's patch 1/2, regardless).
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