5 files changed, 18 insertions, 7 deletions
diff --git a/drivers/gpu/drm/i915/display/g4x_dp.c b/drivers/gpu/drm/i915/display/g4x_dp.c
index 4d279cadf7e2..a0406a71dbde 100644
--- a/drivers/gpu/drm/i915/display/g4x_dp.c
+++ b/drivers/gpu/drm/i915/display/g4x_dp.c
@@ -707,7 +707,7 @@ static void intel_enable_dp(struct intel_atomic_state *state,
 	intel_dp_configure_protocol_converter(intel_dp, pipe_config);
 	intel_dp_check_frl_training(intel_dp);
 	intel_dp_pcon_dsc_configure(intel_dp, pipe_config);
-	intel_dp_start_link_train(intel_dp, pipe_config);
+	intel_dp_start_link_train(state, intel_dp, pipe_config);
 	intel_dp_stop_link_train(intel_dp, pipe_config);
 }
 
diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
index 823c66ad8988..958effb273ff 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.c
+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
@@ -2596,7 +2596,7 @@ static void mtl_ddi_pre_enable_dp(struct intel_atomic_state *state,
 	 *     Pattern, wait for 5 idle patterns (DP_TP_STATUS Min_Idles_Sent)
 	 *     (timeout after 800 us)
 	 */
-	intel_dp_start_link_train(intel_dp, crtc_state);
+	intel_dp_start_link_train(state, intel_dp, crtc_state);
 
 	/* 6.n Set DP_TP_CTL link training to Normal */
 	if (!is_trans_port_sync_mode(crtc_state))
@@ -2738,7 +2738,7 @@ static void tgl_ddi_pre_enable_dp(struct intel_atomic_state *state,
 	 *     Pattern, wait for 5 idle patterns (DP_TP_STATUS Min_Idles_Sent)
 	 *     (timeout after 800 us)
 	 */
-	intel_dp_start_link_train(intel_dp, crtc_state);
+	intel_dp_start_link_train(state, intel_dp, crtc_state);
 
 	/* 7.k Set DP_TP_CTL link training to Normal */
 	if (!is_trans_port_sync_mode(crtc_state))
@@ -2805,7 +2805,7 @@ static void hsw_ddi_pre_enable_dp(struct intel_atomic_state *state,
 						   to_intel_connector(conn_state->connector),
 						   crtc_state);
 	intel_dp_sink_set_fec_ready(intel_dp, crtc_state, true);
-	intel_dp_start_link_train(intel_dp, crtc_state);
+	intel_dp_start_link_train(state, intel_dp, crtc_state);
 	if ((port != PORT_A || DISPLAY_VER(dev_priv) >= 9) &&
 	    !is_trans_port_sync_mode(crtc_state))
 		intel_dp_stop_link_train(intel_dp, crtc_state);
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 5f54b0a9f597..d41c00f720a1 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -5233,7 +5233,7 @@ int intel_dp_retrain_link(struct intel_encoder *encoder,
 
 		intel_dp_check_frl_training(intel_dp);
 		intel_dp_pcon_dsc_configure(intel_dp, crtc_state);
-		intel_dp_start_link_train(intel_dp, crtc_state);
+		intel_dp_start_link_train(NULL, intel_dp, crtc_state);
 		intel_dp_stop_link_train(intel_dp, crtc_state);
 		break;
 	}
diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
index 8caf740e642f..04629a4341ee 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
@@ -1453,6 +1453,7 @@ intel_dp_128b132b_link_train(struct intel_dp *intel_dp,
 
 /**
  * intel_dp_start_link_train - start link training
+ * @state: Atomic state
  * @intel_dp: DP struct
  * @crtc_state: state for CRTC attached to the encoder
  *
@@ -1460,8 +1461,11 @@ intel_dp_128b132b_link_train(struct intel_dp *intel_dp,
  * retraining with reduced link rate/lane parameters if the link training
  * fails.
  * After calling this function intel_dp_stop_link_train() must be called.
+ *
+ * NOTE: @state is only valid for MST links and can be %NULL for SST.
  */
-void intel_dp_start_link_train(struct intel_dp *intel_dp,
+void intel_dp_start_link_train(struct intel_atomic_state *state,
+			       struct intel_dp *intel_dp,
 			       const struct intel_crtc_state *crtc_state)
 {
 	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
@@ -1475,6 +1479,11 @@ void intel_dp_start_link_train(struct intel_dp *intel_dp,
 	 */
 	int lttpr_count = intel_dp_init_lttpr_and_dprx_caps(intel_dp);
 
+	if (drm_WARN_ON(&i915->drm,
+			intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP_MST) &&
+			!state))
+		return;
+
 	if (lttpr_count < 0)
 		/* Still continue with enabling the port and link training. */
 		lttpr_count = 0;
diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.h b/drivers/gpu/drm/i915/display/intel_dp_link_training.h
index 19836a8a4f90..f65823096033 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_link_training.h
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.h
@@ -8,6 +8,7 @@
 
 #include <drm/display/drm_dp_helper.h>
 
+struct intel_atomic_state;
 struct intel_crtc_state;
 struct intel_dp;
 
@@ -25,7 +26,8 @@ void intel_dp_program_link_training_pattern(struct intel_dp *intel_dp,
 void intel_dp_set_signal_levels(struct intel_dp *intel_dp,
 				const struct intel_crtc_state *crtc_state,
 				enum drm_dp_phy dp_phy);
-void intel_dp_start_link_train(struct intel_dp *intel_dp,
+void intel_dp_start_link_train(struct intel_atomic_state *state,
+			       struct intel_dp *intel_dp,
 			       const struct intel_crtc_state *crtc_state);
 void intel_dp_stop_link_train(struct intel_dp *intel_dp,
 			      const struct intel_crtc_state *crtc_state);