drm/i915: Avoid mixing up SST and MST in DDI setup

The MST vs. SST selection should depend purely on the choice of the
connector/encoder. So don't try to determine the correct DDI mode
based on the intel_dp->is_mst, which simply tells us whether the sink
is in MST mode or not. Instead derive the information from the encoder
type. Since the link training code deals in non-fake encoders, we'll
also need to keep a second copy of that information around, which we'll
now designate as 'link_mst'.

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469717448-4297-4-git-send-email-ville.syrjala@linux.intel.comReviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_ddi.c

@@ -1126,7 +1126,6 @@ void intel_ddi_enable_transcoder_func(struct drm_crtc *crtc)
 {
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 	struct intel_encoder *intel_encoder = intel_ddi_get_crtc_encoder(crtc);
-	struct drm_encoder *encoder = &intel_encoder->base;
 	struct drm_device *dev = crtc->dev;
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	enum pipe pipe = intel_crtc->pipe;
@@ -1192,29 +1191,15 @@ void intel_ddi_enable_transcoder_func(struct drm_crtc *crtc)
 			temp |= TRANS_DDI_MODE_SELECT_HDMI;
 		else
 			temp |= TRANS_DDI_MODE_SELECT_DVI;
-
 	} else if (type == INTEL_OUTPUT_ANALOG) {
 		temp |= TRANS_DDI_MODE_SELECT_FDI;
 		temp |= (intel_crtc->config->fdi_lanes - 1) << 1;
-
 	} else if (type == INTEL_OUTPUT_DP ||
 		   type == INTEL_OUTPUT_EDP) {
-		struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
-
-		if (intel_dp->is_mst) {
-			temp |= TRANS_DDI_MODE_SELECT_DP_MST;
-		} else
-			temp |= TRANS_DDI_MODE_SELECT_DP_SST;
-
+		temp |= TRANS_DDI_MODE_SELECT_DP_SST;
 		temp |= DDI_PORT_WIDTH(intel_crtc->config->lane_count);
 	} else if (type == INTEL_OUTPUT_DP_MST) {
-		struct intel_dp *intel_dp = &enc_to_mst(encoder)->primary->dp;
-
-		if (intel_dp->is_mst) {
-			temp |= TRANS_DDI_MODE_SELECT_DP_MST;
-		} else
-			temp |= TRANS_DDI_MODE_SELECT_DP_SST;
-
+		temp |= TRANS_DDI_MODE_SELECT_DP_MST;
 		temp |= DDI_PORT_WIDTH(intel_crtc->config->lane_count);
 	} else {
 		WARN(1, "Invalid encoder type %d for pipe %c\n",
@@ -2139,7 +2124,7 @@ void intel_ddi_prepare_link_retrain(struct intel_dp *intel_dp)
 
 	val = DP_TP_CTL_ENABLE |
 	      DP_TP_CTL_LINK_TRAIN_PAT1 | DP_TP_CTL_SCRAMBLE_DISABLE;
-	if (intel_dp->is_mst)
+	if (intel_dp->link_mst)
 		val |= DP_TP_CTL_MODE_MST;
 	else {
 		val |= DP_TP_CTL_MODE_SST;

drivers/gpu/drm/i915/intel_dp.c

@@ -1651,6 +1651,7 @@ void intel_dp_set_link_params(struct intel_dp *intel_dp,
 {
 	intel_dp->link_rate = pipe_config->port_clock;
 	intel_dp->lane_count = pipe_config->lane_count;
+	intel_dp->link_mst = intel_crtc_has_type(pipe_config, INTEL_OUTPUT_DP_MST);
 }
 
 static void intel_dp_prepare(struct intel_encoder *encoder)

drivers/gpu/drm/i915/intel_drv.h

@@ -852,6 +852,7 @@ struct intel_dp {
 	int link_rate;
 	uint8_t lane_count;
 	uint8_t sink_count;
+	bool link_mst;
 	bool has_audio;
 	bool detect_done;
 	enum hdmi_force_audio force_audio;