Re: [Intel-gfx] [PATCH] drm/i915/display: Fix the dsc check while selecting min_cdclk

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

On Wed, 15 Sep 2021, Vandita Kulkarni <vandita.kulkarni@intel.com> wrote:
> The right parameter that selects second dsc engine is dsc_split.
> Hence use dsc_split instead of slice_count while selecting the
> cdclk in order to accommodate 1ppc limitaion of vdsc.
>
> Fixes: fe01883fdcef ("drm/i915: Get proper min cdclk if vDSC enabled")
> Suggested-by: Jani Nikula <jani.nikula@intel.com>
> Signed-off-by: Vandita Kulkarni <vandita.kulkarni@intel.com>

Sorry for the delay!

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_cdclk.c | 10 ++++------
>  1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c
> index 9aec17b33819..3a1cdb3937aa 100644
> --- a/drivers/gpu/drm/i915/display/intel_cdclk.c
> +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
> @@ -2140,13 +2140,11 @@ int intel_crtc_compute_min_cdclk(const struct intel_crtc_state *crtc_state)
>  	min_cdclk = max(intel_planes_min_cdclk(crtc_state), min_cdclk);
>  
>  	/*
> -	 * VDSC engine can process only 1 pixel per Cd clock.
> -	 * In case VDSC is used and max slice count == 1,
> -	 * max supported pixel clock should be 100% of CD clock.
> -	 * Then do min_cdclk and pixel clock comparison to get cdclk.
> +	 * When we decide to use only one VDSC engine, since
> +	 * each VDSC operates with 1 ppc throughput, pixel clock
> +	 * cannot be higher than the VDSC clock (cdclk)
>  	 */
> -	if (crtc_state->dsc.compression_enable &&
> -	    crtc_state->dsc.slice_count == 1)
> +	if (crtc_state->dsc.compression_enable && !crtc_state->dsc.dsc_split)
>  		min_cdclk = max(min_cdclk, (int)crtc_state->pixel_rate);
>  
>  	/*

-- 
Jani Nikula, Intel Open Source Graphics Center