drm/i915: Handle MST in intel_dp_has_dsc()

Utilize intel_dp_has_dsc() for MST as well.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240517145356.26103-4-ville.syrjala@linux.intel.comReviewed-by: Jani Nikula <jani.nikula@intel.com>

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

@@ -1171,13 +1171,16 @@ bool intel_dp_need_joiner(struct intel_dp *intel_dp,
 	       connector->force_bigjoiner_enable;
 }
 
-static bool intel_dp_has_dsc(const struct intel_connector *connector)
+bool intel_dp_has_dsc(const struct intel_connector *connector)
 {
 	struct drm_i915_private *i915 = to_i915(connector->base.dev);
 
 	if (!HAS_DSC(i915))
 		return false;
 
+	if (connector->mst_port && !HAS_DSC_MST(i915))
+		return false;
+
 	if (!drm_dp_sink_supports_dsc(connector->dp.dsc_dpcd))
 		return false;
 

drivers/gpu/drm/i915/display/intel_dp.h

@@ -87,6 +87,7 @@ bool intel_dp_has_hdmi_sink(struct intel_dp *intel_dp);
 bool intel_dp_is_edp(struct intel_dp *intel_dp);
 bool intel_dp_as_sdp_supported(struct intel_dp *intel_dp);
 bool intel_dp_is_uhbr(const struct intel_crtc_state *crtc_state);
+bool intel_dp_has_dsc(const struct intel_connector *connector);
 int intel_dp_link_symbol_size(int rate);
 int intel_dp_link_symbol_clock(int rate);
 bool intel_dp_is_port_edp(struct drm_i915_private *dev_priv, enum port port);

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

@@ -1459,8 +1459,7 @@ intel_dp_mst_mode_valid_ctx(struct drm_connector *connector,
 		return 0;
 	}
 
-	if (HAS_DSC_MST(dev_priv) &&
-	    drm_dp_sink_supports_dsc(intel_connector->dp.dsc_dpcd)) {
+	if (intel_dp_has_dsc(intel_connector)) {
 		/*
 		 * TBD pass the connector BPC,
 		 * for now U8_MAX so that max BPC on that platform would be picked