Re: [Intel-gfx] [PATCH 09/20] drm/i915/dp: Avoid forcing DSC BPC for MST case

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

On Fri, Jul 28, 2023 at 09:41:39AM +0530, Ankit Nautiyal wrote:
> For MST the bpc is hardcoded to 8, and pipe bpp to 24.
> So avoid forcing DSC bpc for MST case.
> 
> v2: Warn and ignore the debug flag than to bail out. (Jani)
> 
> v3: Fix dbg message to mention forced bpc instead of bpp.
> 
> v4: Fix checkpatch longline warning.
> 
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp.c     | 12 ++++++------
>  drivers/gpu/drm/i915/display/intel_dp_mst.c |  5 +++++
>  2 files changed, 11 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index c5d2e6f538ed..7ec8a478e000 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -1697,14 +1697,14 @@ int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
>  	if (!intel_dp_dsc_supports_format(intel_dp, pipe_config->output_format))
>  		return -EINVAL;
>  
> -	if (compute_pipe_bpp)
> +	if (intel_dp->force_dsc_bpc && compute_pipe_bpp) {
> +		pipe_bpp = intel_dp->force_dsc_bpc * 3;
> +		drm_dbg_kms(&dev_priv->drm, "Input DSC BPC forced to %d\n",
> +			    intel_dp->force_dsc_bpc);
> +	} else if (compute_pipe_bpp) {
>  		pipe_bpp = intel_dp_dsc_compute_bpp(intel_dp, conn_state->max_requested_bpc);
> -	else
> +	} else {
>  		pipe_bpp = pipe_config->pipe_bpp;
> -
> -	if (intel_dp->force_dsc_bpc) {
> -		pipe_bpp = intel_dp->force_dsc_bpc * 3;
> -		drm_dbg_kms(&dev_priv->drm, "Input DSC BPP forced to %d", pipe_bpp);
>  	}
>  
>  	/* Min Input BPC for ICL+ is 8 */
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> index 1f00713fb1ad..dff4717edbd0 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> @@ -361,6 +361,11 @@ static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
>  	/* enable compression if the mode doesn't fit available BW */
>  	drm_dbg_kms(&dev_priv->drm, "Force DSC en = %d\n", intel_dp->force_dsc_en);
>  	if (ret || intel_dp->force_dsc_en) {
> +		/*
> +		 * FIXME: As bpc is hardcoded to 8, as mentioned above,
> +		 * WARN and ignore the debug flag force_dsc_bpc for now.
> +		 */
> +		drm_WARN(&dev_priv->drm, intel_dp->force_dsc_bpc, "Cannot Force BPC for MST\n");
>  		/*
>  		 * Try to get at least some timeslots and then see, if
>  		 * we can fit there with DSC.

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

> -- 
> 2.40.1
>