drm/i915/dsi: use compressed pixel format with DSC

When compression is enabled, configure the DSI transcoder to use
compressed format.
Suggested-by: Vandita Kulkarni <vandita.kulkarni@intel.com>
Cc: Vandita Kulkarni <vandita.kulkarni@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Vandita Kulkarni <vandita.kulkarni@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/0e58022ce5425560b3b31062c41de385a736c8b1.1575974743.git.jani.nikula@intel.com

drivers/gpu/drm/i915/display/icl_dsi.c

@@ -682,6 +682,9 @@ gen11_dsi_configure_transcoder(struct intel_encoder *encoder,
 
 		/* select pixel format */
 		tmp &= ~PIX_FMT_MASK;
+		if (pipe_config->dsc.compression_enable) {
+			tmp |= PIX_FMT_COMPRESSED;
+		} else {
 			switch (intel_dsi->pixel_format) {
 			default:
 				MISSING_CASE(intel_dsi->pixel_format);
@@ -699,6 +702,7 @@ gen11_dsi_configure_transcoder(struct intel_encoder *encoder,
 				tmp |= PIX_FMT_RGB888;
 				break;
 			}
+		}
 
 		if (INTEL_GEN(dev_priv) >= 12) {
 			if (is_vid_mode(intel_dsi))