[Intel-gfx] [PATCH 15/16] drm/i915: Add a workaround for sprite only <-> primary only switching

[Paulo Zanoni]

2014-05-22 11:48 GMT-03:00  <ville.syrjala at linux.intel.com>:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> ILK and IVB don't like switching between sprite only and primary only
> configurations when LP1+ watermarks have been enabled in the recent
> past. Like WaCxSRDisabledForSpriteScaling we can avoid the flash
> by disabling LP1+ watermarks for one frame before the critical plane
> reconfiguration.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_pm.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 66af79d..ea1f990 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -3175,9 +3175,18 @@ static int ilk_update_sprite_wm(struct intel_plane *plane,
>          * when scaling is disabled.
>          *
>          * WaCxSRDisabledForSpriteScaling:ivb
> +        *
> +        * We also seem to need something similar when switching between
> +        * primary only and sprite only configurations. Otherwise the screen
> +        * flashes black. No underrun reported though.
>          */
>         if (IS_IVYBRIDGE(dev) && config->spr.scaled && ilk_disable_lp_wm(crtc))
>                 intel_wait_for_vblank(dev, plane->pipe);
> +       else if (config->pri.enabled != config->spr.enabled &&
> +                config->pri.enabled != params.pri.enabled &&
> +                config->spr.enabled != params.spr.enabled &&
> +                ilk_disable_lp_wm(crtc))
> +               intel_wait_for_vblank(dev, plane->pipe);

Those names are bad. It is not clear at all which one is the "curent"
one and which one is the one we're going to set (between config->x and
params->x). I hope we can fix this later.

Still, the patch seems correct: Reviewed-by: Paulo Zanoni
<paulo.r.zanoni at intel.com>.

>
>         params.pri = config->pri;
>         params.spr = config->spr;
> --
> 1.8.5.5
>
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-- 
Paulo Zanoni