Re: [Intel-gfx] [PATCH 15/20] drm/i915/dp: Add DSC BPC/BPP constraints while selecting pipe bpp with DSC

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

On Fri, Jul 28, 2023 at 09:41:45AM +0530, Ankit Nautiyal wrote:
> Currently we check if the pipe_bpp selected is >= the
> min DSC bpc/bpp requirement. We do not check if it is <= the max DSC
> bpc/bpp requirement.
> 
> Add checks for max DSC BPC/BPP constraints while computing the
> pipe_bpp when DSC is in use.
> 
> v2: Fix the commit message.
> 
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>

Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_dp.c | 34 +++++++++++++++++--------
>  1 file changed, 24 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index c87c3836966c..b296db026fd8 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -1694,13 +1694,27 @@ u8 intel_dp_dsc_min_src_input_bpc(struct drm_i915_private *i915)
>  }
>  
>  static
> -bool is_dsc_pipe_bpp_sufficient(struct drm_i915_private *i915, int pipe_bpp)
> +bool is_dsc_pipe_bpp_sufficient(struct drm_i915_private *i915,
> +				struct drm_connector_state *conn_state,
> +				struct link_config_limits *limits,
> +				int pipe_bpp)
>  {
> -	return pipe_bpp >= intel_dp_dsc_min_src_input_bpc(i915) * 3;
> +	u8 dsc_max_bpc, dsc_min_bpc, dsc_max_pipe_bpp, dsc_min_pipe_bpp;
> +
> +	dsc_max_bpc = min(intel_dp_dsc_max_src_input_bpc(i915), conn_state->max_requested_bpc);
> +	dsc_min_bpc = intel_dp_dsc_min_src_input_bpc(i915);
> +
> +	dsc_max_pipe_bpp = min(dsc_max_bpc * 3, limits->max_bpp);
> +	dsc_min_pipe_bpp = max(dsc_min_bpc * 3, limits->min_bpp);
> +
> +	return pipe_bpp >= dsc_min_pipe_bpp &&
> +	       pipe_bpp <= dsc_max_pipe_bpp;
>  }
>  
>  static
> -int intel_dp_force_dsc_pipe_bpp(struct intel_dp *intel_dp)
> +int intel_dp_force_dsc_pipe_bpp(struct intel_dp *intel_dp,
> +				struct drm_connector_state *conn_state,
> +				struct link_config_limits *limits)
>  {
>  	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
>  	int forced_bpp;
> @@ -1710,7 +1724,7 @@ int intel_dp_force_dsc_pipe_bpp(struct intel_dp *intel_dp)
>  
>  	forced_bpp = intel_dp->force_dsc_bpc * 3;
>  
> -	if (is_dsc_pipe_bpp_sufficient(i915, forced_bpp)) {
> +	if (is_dsc_pipe_bpp_sufficient(i915, conn_state, limits, forced_bpp)) {
>  		drm_dbg_kms(&i915->drm, "Input DSC BPC forced to %d\n", intel_dp->force_dsc_bpc);
>  		return forced_bpp;
>  	}
> @@ -1732,16 +1746,16 @@ static int intel_dp_dsc_compute_pipe_bpp(struct intel_dp *intel_dp,
>  	u16 output_bpp, dsc_max_compressed_bpp = 0;
>  	int forced_bpp, pipe_bpp;
>  
> -	forced_bpp = intel_dp_force_dsc_pipe_bpp(intel_dp);
> +	forced_bpp = intel_dp_force_dsc_pipe_bpp(intel_dp, conn_state, limits);
>  
>  	if (forced_bpp) {
>  		pipe_bpp = forced_bpp;
>  	} else {
>  		pipe_bpp = intel_dp_dsc_compute_max_bpp(intel_dp, conn_state->max_requested_bpc);
>  
> -		if (!is_dsc_pipe_bpp_sufficient(i915, pipe_bpp)) {
> +		if (!is_dsc_pipe_bpp_sufficient(i915, conn_state, limits, pipe_bpp)) {
>  			drm_dbg_kms(&i915->drm,
> -				    "Computed BPC less than min supported by source for DSC\n");
> +				    "Computed BPC is not in DSC BPC limits\n");
>  			return -EINVAL;
>  		}
>  	}
> @@ -1783,7 +1797,7 @@ static int intel_edp_dsc_compute_pipe_bpp(struct intel_dp *intel_dp,
>  	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
>  	int pipe_bpp, forced_bpp;
>  
> -	forced_bpp = intel_dp_force_dsc_pipe_bpp(intel_dp);
> +	forced_bpp = intel_dp_force_dsc_pipe_bpp(intel_dp, conn_state, limits);
>  
>  	if (forced_bpp) {
>  		pipe_bpp = forced_bpp;
> @@ -1791,9 +1805,9 @@ static int intel_edp_dsc_compute_pipe_bpp(struct intel_dp *intel_dp,
>  		/* For eDP use max bpp that can be supported with DSC. */
>  		pipe_bpp = intel_dp_dsc_compute_max_bpp(intel_dp,
>  							conn_state->max_requested_bpc);
> -		if (!is_dsc_pipe_bpp_sufficient(i915, pipe_bpp)) {
> +		if (!is_dsc_pipe_bpp_sufficient(i915, conn_state, limits, pipe_bpp)) {
>  			drm_dbg_kms(&i915->drm,
> -				    "Computed BPC less than min supported by source for DSC\n");
> +				    "Computed BPC is not in DSC BPC limits\n");
>  			return -EINVAL;
>  		}
>  	}
> -- 
> 2.40.1
>