drm/i915/display: Fix the dsc check while selecting min_cdclk

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: fe01883f ("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>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210915054338.29869-1-vandita.kulkarni@intel.com

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);
 
 	/*