drm/i915/dp_mst: Enable VC payload allocation after transcoder is enabled

The spec requires enabling the MST Virtual Channel payload allocation
- in a separate step - after the transcoder is enabled, follow this.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200623082411.3889-1-imre.deak@intel.com

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

@@ -1653,7 +1653,6 @@ void intel_ddi_enable_transcoder_func(struct intel_encoder *encoder,
 	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
 	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
-	u32 ctl;
 
 	if (INTEL_GEN(dev_priv) >= 11) {
 		enum transcoder master_transcoder = crtc_state->master_transcoder;
@@ -1671,10 +1670,9 @@ void intel_ddi_enable_transcoder_func(struct intel_encoder *encoder,
 			       TRANS_DDI_FUNC_CTL2(cpu_transcoder), ctl2);
 	}
 
-	ctl = intel_ddi_transcoder_func_reg_val_get(encoder, crtc_state);
-	if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP_MST))
-		ctl |= TRANS_DDI_DP_VC_PAYLOAD_ALLOC;
-	intel_de_write(dev_priv, TRANS_DDI_FUNC_CTL(cpu_transcoder), ctl);
+	intel_de_write(dev_priv, TRANS_DDI_FUNC_CTL(cpu_transcoder),
+		       intel_ddi_transcoder_func_reg_val_get(encoder,
+							     crtc_state));
 }
 
 /*

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

@@ -529,6 +529,7 @@ static void intel_mst_enable_dp(struct intel_atomic_state *state,
 	struct intel_digital_port *intel_dig_port = intel_mst->primary;
 	struct intel_dp *intel_dp = &intel_dig_port->dp;
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
+	u32 val;
 
 	drm_WARN_ON(&dev_priv->drm, pipe_config->has_pch_encoder);
 
@@ -536,6 +537,13 @@ static void intel_mst_enable_dp(struct intel_atomic_state *state,
 
 	intel_ddi_enable_transcoder_func(encoder, pipe_config);
 
+	val = intel_de_read(dev_priv,
+			    TRANS_DDI_FUNC_CTL(pipe_config->cpu_transcoder));
+	val |= TRANS_DDI_DP_VC_PAYLOAD_ALLOC;
+	intel_de_write(dev_priv,
+		       TRANS_DDI_FUNC_CTL(pipe_config->cpu_transcoder),
+		       val);
+
 	drm_dbg_kms(&dev_priv->drm, "active links %d\n",
 		    intel_dp->active_mst_links);