[Intel-gfx] [PATCH 5/6] drm/i915: Balance prepare_fb/cleanup_fb

[Chris Wilson]

Quoting Ville Syrjala (2020-01-10 18:32:27)
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> intel_prepare_plane_fb() bails early if there is no fb (or rather
> no obj, which is the same thing). intel_cleanup_plane_fb() does not.
> This means the steps performed by intel_cleanup_plane_fb() aren't
> balanced with with what was done intel_prepare_plane_fb() if there
> is no fb for the plane. These hooks get called for every plane in
> the state regardless of whether they have an fb or not.
> 
> Add a matching null obj check to intel_cleanup_plane_fb() to restore
> the balance.
> 
> Note that intel_cleanup_plane_fb() has sufficient protections
> already in place that the imbalance doesn't cause any real problems.
> But having things be in balance seems nicer anyway, and might help
> avoid some surprises in the future.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_display.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index 27b43822344b..f79a6376bbf0 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -15868,6 +15868,10 @@ intel_cleanup_plane_fb(struct drm_plane *plane,
>         struct intel_atomic_state *state =
>                 to_intel_atomic_state(old_plane_state->uapi.state);
>         struct drm_i915_private *dev_priv = to_i915(plane->dev);
> +       struct drm_i915_gem_object *obj = intel_fb_obj(old_plane_state->hw.fb);
> +
> +       if (!obj)
> +               return;
>  
>         if (state->rps_interactive) {
>                 intel_rps_mark_interactive(&dev_priv->gt.rps, false);

Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris