[Intel-gfx] [PATCH] drm/i915: Wait for scanout to stop when sanitizing planes

[Chris Wilson]

Quoting Ville Syrjala (2021-02-17 16:20:50)
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> When we sanitize planes let's wait for the scanout to stop
> before we let the subsequent code tear down the ggtt mappings
> and whatnot. Cures an underrun on my ivb when I boot with
> VT-d enabled and the BIOS fb gets thrown out due to stolen
> being considered unusable with VT-d active.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_display.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index acade004e8b1..3e2c192ec708 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -2403,6 +2403,7 @@ static void intel_plane_disable_noatomic(struct intel_crtc *crtc,
>                 intel_set_cpu_fifo_underrun_reporting(dev_priv, crtc->pipe, false);
>  
>         intel_disable_plane(plane, crtc_state);
> +       intel_wait_for_vblank(dev_priv, crtc->pipe);

I could only find paths here from sanitize, so it looks safe from the
prospect of adding random delays to userspace.

Makes sense so,
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris