Re: [PATCH] drm/i915/display: update handling of FBC when VT-d active workaround

[Jani Nikula <jani.nikula@linux.intel.com>]

On Tue, 28 May 2024, Vinod Govindapillai <vinod.govindapillai@intel.com> wrote:
> Move the handling of the disabling FBC when VT-d is active wa
> as part of the intel_fbc_check_plane()

I can see that from the code.

The commit message must answer the question "why".

BR,
Jani.

>
> Bspec: 21664
> Signed-off-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_fbc.c | 22 ++++++----------------
>  1 file changed, 6 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
> index e9189a864f69..492dc26ecfa2 100644
> --- a/drivers/gpu/drm/i915/display/intel_fbc.c
> +++ b/drivers/gpu/drm/i915/display/intel_fbc.c
> @@ -1235,6 +1235,12 @@ static int intel_fbc_check_plane(struct intel_atomic_state *state,
>  		return 0;
>  	}
>  
> +	/* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl,bxt */
> +	if (i915_vtd_active(i915) && (IS_SKYLAKE(i915) || IS_BROXTON(i915))) {
> +		plane_state->no_fbc_reason = "VT-d enabled";
> +		return true;
> +	}
> +
>  	crtc_state = intel_atomic_get_new_crtc_state(state, crtc);
>  
>  	if (crtc_state->hw.adjusted_mode.flags & DRM_MODE_FLAG_INTERLACE) {
> @@ -1820,19 +1826,6 @@ static int intel_sanitize_fbc_option(struct drm_i915_private *i915)
>  	return 0;
>  }
>  
> -static bool need_fbc_vtd_wa(struct drm_i915_private *i915)
> -{
> -	/* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl,bxt */
> -	if (i915_vtd_active(i915) &&
> -	    (IS_SKYLAKE(i915) || IS_BROXTON(i915))) {
> -		drm_info(&i915->drm,
> -			 "Disabling framebuffer compression (FBC) to prevent screen flicker with VT-d enabled\n");
> -		return true;
> -	}
> -
> -	return false;
> -}
> -
>  void intel_fbc_add_plane(struct intel_fbc *fbc, struct intel_plane *plane)
>  {
>  	plane->fbc = fbc;
> @@ -1878,9 +1871,6 @@ void intel_fbc_init(struct drm_i915_private *i915)
>  {
>  	enum intel_fbc_id fbc_id;
>  
> -	if (need_fbc_vtd_wa(i915))
> -		DISPLAY_RUNTIME_INFO(i915)->fbc_mask = 0;
> -
>  	i915->display.params.enable_fbc = intel_sanitize_fbc_option(i915);
>  	drm_dbg_kms(&i915->drm, "Sanitized enable_fbc value: %d\n",
>  		    i915->display.params.enable_fbc);

-- 
Jani Nikula, Intel