Re: [Intel-gfx] [PATCH 10/20] drm/i915/dp: Add functions to get min/max src input bpc with DSC

["Lisovskiy, Stanislav" <stanislav.lisovskiy@intel.com>]

On Fri, Jul 28, 2023 at 09:41:40AM +0530, Ankit Nautiyal wrote:
> Separate out functions for getting maximum and minimum input BPC based
> on platforms, when DSC is used.
> 
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp.c | 38 +++++++++++++++++++------
>  1 file changed, 30 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 7ec8a478e000..f41de126a8d3 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -1535,6 +1535,18 @@ intel_dp_compute_link_config_wide(struct intel_dp *intel_dp,
>  	return -EINVAL;
>  }
>  
> +static
> +u8 intel_dp_dsc_max_src_input_bpc(struct drm_i915_private *i915)
> +{
> +	/* Max DSC Input BPC for ICL is 10 and for TGL+ is 12 */
> +	if (DISPLAY_VER(i915) >= 12)
> +		return 12;
> +	if (DISPLAY_VER(i915) == 11)
> +		return 10;
> +
> +	return 0;
> +}
> +
>  int intel_dp_dsc_compute_bpp(struct intel_dp *intel_dp, u8 max_req_bpc)
>  {
>  	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> @@ -1542,11 +1554,12 @@ int intel_dp_dsc_compute_bpp(struct intel_dp *intel_dp, u8 max_req_bpc)
>  	u8 dsc_bpc[3] = {0};
>  	u8 dsc_max_bpc;
>  
> -	/* Max DSC Input BPC for ICL is 10 and for TGL+ is 12 */
> -	if (DISPLAY_VER(i915) >= 12)
> -		dsc_max_bpc = min_t(u8, 12, max_req_bpc);
> -	else
> -		dsc_max_bpc = min_t(u8, 10, max_req_bpc);
> +	dsc_max_bpc = intel_dp_dsc_max_src_input_bpc(i915);
> +
> +	if (!dsc_max_bpc)
> +		return dsc_max_bpc;
> +
> +	dsc_max_bpc = min_t(u8, dsc_max_bpc, max_req_bpc);
>  
>  	num_bpc = drm_dp_dsc_sink_supported_input_bpcs(intel_dp->dsc_dpcd,
>  						       dsc_bpc);
> @@ -1674,6 +1687,16 @@ static bool intel_dp_dsc_supports_format(struct intel_dp *intel_dp,
>  	return drm_dp_dsc_sink_supports_format(intel_dp->dsc_dpcd, sink_dsc_format);
>  }
>  
> +static
> +u8 intel_dp_dsc_min_src_input_bpc(struct drm_i915_private *i915)
> +{
> +	/* Min DSC Input BPC for ICL+ is 8 */
> +	if (DISPLAY_VER(i915) >= 11)
> +		return 8;
> +
> +	return 0;

So does it mean that for anything below gen 11, there is no limit at all?
Also it means that the condition below will never be executed for gen <= 11.

Stan

> +}
> +
>  int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
>  				struct intel_crtc_state *pipe_config,
>  				struct drm_connector_state *conn_state,
> @@ -1707,10 +1730,9 @@ int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
>  		pipe_bpp = pipe_config->pipe_bpp;
>  	}
>  
> -	/* Min Input BPC for ICL+ is 8 */
> -	if (pipe_bpp < 8 * 3) {
> +	if (pipe_bpp < intel_dp_dsc_min_src_input_bpc(dev_priv) * 3) {
>  		drm_dbg_kms(&dev_priv->drm,
> -			    "No DSC support for less than 8bpc\n");
> +			    "Computed BPC less than min supported by source for DSC\n");
>  		return -EINVAL;
>  	}
>  
> -- 
> 2.40.1
>