drm/i915/ddi: 128b/132b SST also needs DP_TP_CTL_MODE_MST

It's not very clearly specified, and the hardware bit is ill-named, but
128b/132b SST also needs the MST mode set in the DP_TP_CTL register.

This is preparation for enabling 128b/132b SST. This path is not
reachable yet.

Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/b29fbba8c979a8bab2bf03088610fe408faaf704.1735912293.git.jani.nikula@intel.com

Author: jnikula

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

@@ -3655,7 +3655,8 @@ static void mtl_ddi_prepare_link_retrain(struct intel_dp *intel_dp,
 
 	/* 6.d Configure and enable DP_TP_CTL with link training pattern 1 selected */
 	dp_tp_ctl = DP_TP_CTL_ENABLE | DP_TP_CTL_LINK_TRAIN_PAT1;
-	if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP_MST)) {
+	if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP_MST) ||
+	    intel_dp_is_uhbr(crtc_state)) {
 		dp_tp_ctl |= DP_TP_CTL_MODE_MST;
 	} else {
 		dp_tp_ctl |= DP_TP_CTL_MODE_SST;
@@ -3715,7 +3716,8 @@ static void intel_ddi_prepare_link_retrain(struct intel_dp *intel_dp,
 	}
 
 	dp_tp_ctl = DP_TP_CTL_ENABLE | DP_TP_CTL_LINK_TRAIN_PAT1;
-	if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP_MST)) {
+	if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP_MST) ||
+	    intel_dp_is_uhbr(crtc_state)) {
 		dp_tp_ctl |= DP_TP_CTL_MODE_MST;
 	} else {
 		dp_tp_ctl |= DP_TP_CTL_MODE_SST;