drm/i915: Implement proper fallback training for MST

index 7d25c42f22db..972a7e9634ab 100644
@@ -1705,8 +1705,11 @@ int drm_atomic_check_only(struct drm_atomic_state *state)
 	if (config->funcs->atomic_check)
 		ret = config->funcs->atomic_check(state->dev, state);
 
-	if (ret)
+	if (ret) {
+		DRM_DEBUG_ATOMIC("atomic driver check for %p failed: %d\n",
+				 state, ret);
 		return ret;
+	}
 
 	if (!state->allow_modeset) {
 		for_each_new_crtc_in_state(state, crtc, crtc_state, i) {

index e04050ea3e28..18edb9628a54 100644
@@ -15471,20 +15471,28 @@ void intel_connector_unregister(struct drm_connector *connector)
 
 static void intel_hpd_poll_fini(struct drm_device *dev)
 {
-	struct intel_connector *connector;
 	struct drm_connector_list_iter conn_iter;
+	struct intel_connector *connector;
+	struct intel_encoder *encoder;
+	struct intel_dp *intel_dp;
 
 	/* Kill all the work that may have been queued by hpd. */
 	drm_connector_list_iter_begin(dev, &conn_iter);
 	for_each_intel_connector_iter(connector, &conn_iter) {
-		if (connector->modeset_retry_work.func)
-			cancel_work_sync(&connector->modeset_retry_work);
 		if (connector->hdcp_shim) {
 			cancel_delayed_work_sync(&connector->hdcp_check_work);
 			cancel_work_sync(&connector->hdcp_prop_work);
 		}
 	}
 	drm_connector_list_iter_end(&conn_iter);
+
+	for_each_intel_encoder(dev, encoder) {
+		if (encoder->type == INTEL_OUTPUT_DP ||
+		    encoder->type == INTEL_OUTPUT_EDP) {
+			intel_dp = enc_to_intel_dp(&encoder->base);
+			cancel_work_sync(&intel_dp->modeset_retry_work);
+		}
+	}
 }
 
 void intel_modeset_cleanup(struct drm_device *dev)

index 62f82c4298ac..fbb467bc227d 100644
@@ -6249,12 +6249,10 @@ static bool intel_edp_init_connector(struct intel_dp *intel_dp,
 
 static void intel_dp_modeset_retry_work_fn(struct work_struct *work)
 {
-	struct intel_connector *intel_connector;
-	struct drm_connector *connector;
+	struct intel_dp *intel_dp = container_of(work, typeof(*intel_dp),
+						 modeset_retry_work);
+	struct drm_connector *connector = &intel_dp->attached_connector->base;
 
-	intel_connector = container_of(work, typeof(*intel_connector),
-				       modeset_retry_work);
-	connector = &intel_connector->base;
 	DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n", connector->base.id,
 		      connector->name);
 

@@ -6283,7 +6281,7 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
 	int type;
 
 	/* Initialize the work for modeset in case of link train failure */
-	INIT_WORK(&intel_connector->modeset_retry_work,
+	INIT_WORK(&intel_dp->modeset_retry_work,
 		  intel_dp_modeset_retry_work_fn);
 
 	if (WARN(intel_dig_port->max_lanes < 1,

index f59b59bb0a21..2cfa58ce1f95 100644
@@ -340,7 +340,7 @@ intel_dp_start_link_train(struct intel_dp *intel_dp)
 							     intel_dp->link_rate,
 							     intel_dp->lane_count))
 			/* Schedule a Hotplug Uevent to userspace to start modeset */
-			schedule_work(&intel_connector->modeset_retry_work);
+			schedule_work(&intel_dp->modeset_retry_work);
 	} else {
 		DRM_ERROR("[CONNECTOR:%d:%s] Link Training failed at link rate = %d, lane count = %d",
 			  intel_connector->base.base.id,

index 5bd2263407b2..742d53495974 100644
@@ -406,9 +406,6 @@ struct intel_connector {
 
 	struct intel_dp *mst_port;
 
-	/* Work struct to schedule a uevent on link train failure */
-	struct work_struct modeset_retry_work;
-
 	const struct intel_hdcp_shim *hdcp_shim;
 	struct mutex hdcp_mutex;
 	uint64_t hdcp_value; /* protected by hdcp_mutex */

@@ -1143,6 +1140,9 @@ struct intel_dp {
 
 	/* Displayport compliance testing */
 	struct intel_dp_compliance compliance;
+
+	/* Work struct to schedule a uevent on link train failure */
+	struct work_struct modeset_retry_work;
 };
 
 struct intel_lspcon {

index 6fac4129e6a2..ba67f1782a04 100644
@@ -2622,7 +2622,7 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
 	struct drm_dp_mst_topology_state *topology_state;
 	int req_slots;
 
-	topology_state = drm_atomic_get_mst_topology_state(state, mgr);
+	topology_state = drm_atomic_dp_mst_get_topology_state(state, mgr);
 	if (IS_ERR(topology_state))
 		return PTR_ERR(topology_state);
 

@@ -2662,7 +2662,7 @@ int drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,
 {
 	struct drm_dp_mst_topology_state *topology_state;
 
-	topology_state = drm_atomic_get_mst_topology_state(state, mgr);
+	topology_state = drm_atomic_dp_mst_get_topology_state(state, mgr);
 	if (IS_ERR(topology_state))
 		return PTR_ERR(topology_state);
 

@@ -3129,7 +3129,7 @@ static const struct drm_private_state_funcs mst_state_funcs = {
 };
 
 /**
- * drm_atomic_get_mst_topology_state: get MST topology state
+ * drm_atomic_dp_mst_get_topology_state: get MST topology state
  *
  * @state: global atomic state
  * @mgr: MST topology manager, also the private object in this case

@@ -3143,15 +3143,16 @@ static const struct drm_private_state_funcs mst_state_funcs = {
  *
  * The MST topology state or error pointer.
  */
-struct drm_dp_mst_topology_state *drm_atomic_get_mst_topology_state(struct drm_atomic_state *state,
-								    struct drm_dp_mst_topology_mgr *mgr)
+struct drm_dp_mst_topology_state *
+drm_atomic_dp_mst_get_topology_state(struct drm_atomic_state *state,
+				     struct drm_dp_mst_topology_mgr *mgr)
 {
 	struct drm_device *dev = mgr->dev;
 
 	WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
 	return to_dp_mst_topology_state(drm_atomic_get_private_obj_state(state, &mgr->base));
 }
-EXPORT_SYMBOL(drm_atomic_get_mst_topology_state);
+EXPORT_SYMBOL(drm_atomic_dp_mst_get_topology_state);
 
 /**
  * drm_dp_mst_topology_mgr_init - initialise a topology manager

index 7f78d26a0766..2f6203407fd2 100644
@@ -623,8 +623,10 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
 
 void drm_dp_mst_topology_mgr_suspend(struct drm_dp_mst_topology_mgr *mgr);
 int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr);
-struct drm_dp_mst_topology_state *drm_atomic_get_mst_topology_state(struct drm_atomic_state *state,
-								    struct drm_dp_mst_topology_mgr *mgr);
+
+struct drm_dp_mst_topology_state *
+drm_atomic_dp_mst_get_topology_state(struct drm_atomic_state *state,
+				     struct drm_dp_mst_topology_mgr *mgr);
 int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
 				  struct drm_dp_mst_topology_mgr *mgr,
 				  struct drm_dp_mst_port *port, int pbn);

index 2f6203407fd2..5ca77dcf4f90 100644
@@ -409,7 +409,6 @@ struct drm_dp_payload {
 struct drm_dp_mst_topology_state {
 	struct drm_private_state base;
 	int avail_slots;
-	struct drm_atomic_state *state;
 	struct drm_dp_mst_topology_mgr *mgr;
 };
 

@@ -497,11 +496,6 @@ struct drm_dp_mst_topology_mgr {
 	 */
 	int pbn_div;
 
-	/**
-	 * @state: State information for topology manager
-	 */
-	struct drm_dp_mst_topology_state *state;
-
 	/**
 	 * @funcs: Atomic helper callbacks
 	 */

index e42a28e3adc5..2c3660c36732 100644
@@ -3626,9 +3626,17 @@ static int amdgpu_dm_connector_init(struct amdgpu_display_manager *dm,
 
 	drm_connector_register(&aconnector->base);
 
-	if (connector_type == DRM_MODE_CONNECTOR_DisplayPort
-		|| connector_type == DRM_MODE_CONNECTOR_eDP)
-		amdgpu_dm_initialize_dp_connector(dm, aconnector);
+	if (connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
+	    connector_type == DRM_MODE_CONNECTOR_eDP) {
+		res = amdgpu_dm_initialize_dp_connector(dm, aconnector);
+		if (res) {
+			drm_connector_unregister(&aconnector->base);
+			drm_connector_cleanup(&aconnector->base);
+			aconnector->connector_id = -1;
+
+			goto out_free;
+		}
+	}
 
 #if defined(CONFIG_BACKLIGHT_CLASS_DEVICE) ||\
 	defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE)

58 lines not on this page · raw message

index 8cf51da26657..d28fb456d2d5 100644
@@ -29,8 +29,8 @@
 struct amdgpu_display_manager;
 struct amdgpu_dm_connector;
 
-void amdgpu_dm_initialize_dp_connector(struct amdgpu_display_manager *dm,
-				       struct amdgpu_dm_connector *aconnector);
+int amdgpu_dm_initialize_dp_connector(struct amdgpu_display_manager *dm,
+				      struct amdgpu_dm_connector *aconnector);
 void dm_dp_mst_dc_sink_create(struct drm_connector *connector);
 
 #endif

148 lines not on this page · raw message

index 9e6956c08688..cf844cfd2bb0 100644
@@ -587,19 +587,30 @@ intel_dp_create_fake_mst_encoders(struct intel_digital_port *intel_dig_port)
 	return true;
 }
 
+static const struct drm_private_state_funcs mst_state_funcs = {
+	.atomic_destroy_state = drm_atomic_dp_mst_destroy_topology_state,
+	.atomic_duplicate_state = drm_atomic_dp_mst_duplicate_topology_state,
+};
+
 int
 intel_dp_mst_encoder_init(struct intel_digital_port *intel_dig_port, int conn_base_id)
 {
 	struct intel_dp *intel_dp = &intel_dig_port->dp;
+	struct drm_dp_mst_topology_state *mst_state;
 	struct drm_device *dev = intel_dig_port->base.base.dev;
 	int ret;
 
+	mst_state = kzalloc(sizeof(*mst_state), GFP_KERNEL);
+	if (!mst_state)
+		return -ENOMEM;
+
 	intel_dp->can_mst = true;
 	intel_dp->mst_mgr.cbs = &mst_cbs;
+	intel_dp->mst_mgr.funcs = &mst_state_funcs;
 
 	/* create encoders */
 	intel_dp_create_fake_mst_encoders(intel_dig_port);
-	ret = drm_dp_mst_topology_mgr_init(&intel_dp->mst_mgr, dev,
+	ret = drm_dp_mst_topology_mgr_init(&intel_dp->mst_mgr, mst_state, dev,
 					   &intel_dp->aux, 16, 3, conn_base_id);
 	if (ret) {
 		intel_dp->can_mst = false;

index 8bd739cfd00d..200db30a9c43 100644
@@ -3310,6 +3310,12 @@ nv50_mstm = {
 	.hotplug = nv50_mstm_hotplug,
 };
 
+static const struct drm_private_state_funcs
+nv50_mst_state_funcs = {
+	.atomic_duplicate_state = drm_atomic_dp_mst_duplicate_topology_state,
+	.atomic_destroy_state = drm_atomic_dp_mst_destroy_topology_state,
+};
+
 void
 nv50_mstm_service(struct nv50_mstm *mstm)
 {

@@ -3438,6 +3444,7 @@ nv50_mstm_new(struct nouveau_encoder *outp, struct drm_dp_aux *aux, int aux_max,
 {
 	const int max_payloads = hweight8(outp->dcb->heads);
 	struct drm_device *dev = outp->base.base.dev;
+	struct drm_dp_mst_topology_state *state;
 	struct nv50_mstm *mstm;
 	int ret, i;
 	u8 dpcd;

@@ -3454,10 +3461,18 @@ nv50_mstm_new(struct nouveau_encoder *outp, struct drm_dp_aux *aux, int aux_max,
 
 	if (!(mstm = *pmstm = kzalloc(sizeof(*mstm), GFP_KERNEL)))
 		return -ENOMEM;
+
+	state = kzalloc(sizeof(*state), GFP_KERNEL);
+	if (!state) {
+		kfree(mstm);
+		return -ENOMEM;
+	}
 	mstm->outp = outp;
 	mstm->mgr.cbs = &nv50_mstm;
+	mstm->mgr.funcs = &nv50_mst_state_funcs;
 
-	ret = drm_dp_mst_topology_mgr_init(&mstm->mgr, dev, aux, aux_max,
+	ret = drm_dp_mst_topology_mgr_init(&mstm->mgr, state, dev,
+					   aux, aux_max,
 					   max_payloads, conn_base_id);
 	if (ret)
 		return ret;

index cd8a3ee16649..6edf52404256 100644
@@ -335,6 +335,11 @@ static const struct drm_dp_mst_topology_cbs mst_cbs = {
 	.hotplug = radeon_dp_mst_hotplug,
 };
 
+static const struct drm_private_state_funcs mst_state_funcs = {
+	.atomic_duplicate_state = drm_atomic_dp_mst_duplicate_topology_state,
+	.atomic_destroy_state = drm_atomic_dp_mst_destroy_topology_state,
+};
+
 static struct
 radeon_connector *radeon_mst_find_connector(struct drm_encoder *encoder)
 {

@@ -657,12 +662,18 @@ int
 radeon_dp_mst_init(struct radeon_connector *radeon_connector)
 {
 	struct drm_device *dev = radeon_connector->base.dev;
+	struct drm_dp_mst_topology_state *state =
+		kzalloc(sizeof(*state), GFP_KERNEL);
 
+	if (!state)
+		return -ENOMEM;
 	if (!radeon_connector->ddc_bus->has_aux)
 		return 0;
 
 	radeon_connector->mst_mgr.cbs = &mst_cbs;
-	return drm_dp_mst_topology_mgr_init(&radeon_connector->mst_mgr, dev,
+	radeon_connector->mst_mgr.funcs = &mst_state_funcs;
+	return drm_dp_mst_topology_mgr_init(&radeon_connector->mst_mgr,
+					    state, dev,
 					    &radeon_connector->ddc_bus->aux, 16, 6,
 					    radeon_connector->base.base.id);
 }

index 5ca77dcf4f90..ad1aaec8d514 100644
@@ -565,6 +565,7 @@ struct drm_dp_mst_topology_mgr {
 };
 
 int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
+				 struct drm_dp_mst_topology_state *state,
 				 struct drm_device *dev, struct drm_dp_aux *aux,
 				 int max_dpcd_transaction_bytes,
 				 int max_payloads, int conn_base_id);

@@ -621,6 +622,13 @@ int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr);
 struct drm_dp_mst_topology_state *
 drm_atomic_dp_mst_get_topology_state(struct drm_atomic_state *state,
 				     struct drm_dp_mst_topology_mgr *mgr);
+struct drm_private_state *drm_atomic_dp_mst_duplicate_topology_state(struct drm_private_obj *obj);
+int __drm_atomic_dp_mst_duplicate_topology_state(struct drm_dp_mst_topology_mgr *mgr,
+						 struct drm_dp_mst_topology_state *state);
+void drm_atomic_dp_mst_destroy_topology_state(struct drm_private_obj *obj,
+					      struct drm_private_state *state);
+void __drm_atomic_dp_mst_destroy_topology_state(struct drm_dp_mst_topology_state *state);
+
 int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
 				  struct drm_dp_mst_topology_mgr *mgr,
 				  struct drm_dp_mst_port *port, int pbn);

index fbd7888ebca8..981bd0f7d3ab 100644
@@ -2096,6 +2096,15 @@ static bool drm_dp_get_vc_payload_bw(int dp_link_bw,
 	return true;
 }
 
+static void drm_dp_mst_topology_reset_state(struct drm_dp_mst_topology_mgr *mgr)
+{
+	struct drm_dp_mst_topology_state *state =
+		to_dp_mst_topology_state(mgr->base.state);
+
+	if (mgr->cbs->reset_state)
+		mgr->cbs->reset_state(state);
+}
+
 /**
  * drm_dp_mst_topology_mgr_set_mst() - Set the MST state for a topology manager
  * @mgr: manager to set state for

@@ -2171,6 +2180,7 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms
 		mgr->payload_mask = 0;
 		set_bit(0, &mgr->payload_mask);
 		mgr->vcpi_mask = 0;
+		drm_dp_mst_topology_reset_state(mgr);
 	}
 
 out_unlock:

index ad1aaec8d514..3a7378cd5bd1 100644
@@ -381,6 +381,7 @@ struct drm_dp_sideband_msg_tx {
 
 /* sideband msg handler */
 struct drm_dp_mst_topology_mgr;
+struct drm_dp_mst_topology_state;
 struct drm_dp_mst_topology_cbs {
 	/* create a connector for a port */
 	struct drm_connector *(*add_connector)(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port, const char *path);

@@ -388,7 +389,7 @@ struct drm_dp_mst_topology_cbs {
 	void (*destroy_connector)(struct drm_dp_mst_topology_mgr *mgr,
 				  struct drm_connector *connector);
 	void (*hotplug)(struct drm_dp_mst_topology_mgr *mgr);
-
+	void (*reset_state)(struct drm_dp_mst_topology_state *state);
 };
 
 #define DP_MAX_PAYLOAD (sizeof(unsigned long) * 8)

index cf844cfd2bb0..19de0b5a7a40 100644
@@ -41,8 +41,11 @@ static bool intel_dp_mst_compute_config(struct intel_encoder *encoder,
 	struct intel_connector *connector =
 		to_intel_connector(conn_state->connector);
 	struct drm_atomic_state *state = pipe_config->base.state;
+	struct drm_dp_mst_topology_state *mst_state =
+		drm_atomic_dp_mst_get_topology_state(state, &intel_dp->mst_mgr);
+	struct intel_dp_mst_topology_state *intel_mst_state;
 	int bpp;
-	int lane_count, slots;
+	int slots;
 	const struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode;
 	int mst_pbn;
 	bool reduce_m_n = drm_dp_has_quirk(&intel_dp->desc,

@@ -55,18 +58,22 @@ static bool intel_dp_mst_compute_config(struct intel_encoder *encoder,
 		DRM_DEBUG_KMS("Setting pipe bpp to %d\n",
 			      bpp);
 	}
+
+	intel_mst_state =
+		to_intel_dp_mst_topology_state(mst_state);
 	/*
 	 * for MST we always configure max link bw - the spec doesn't
 	 * seem to suggest we should do otherwise.
 	 */
-	lane_count = intel_dp_max_lane_count(intel_dp);
-
-	pipe_config->lane_count = lane_count;
+	if (!intel_mst_state->link_rate || !intel_mst_state->lane_count) {
+		intel_mst_state->link_rate = intel_dp_max_link_rate(intel_dp);
+		intel_mst_state->lane_count = intel_dp_max_lane_count(intel_dp);
+	}
 
+	pipe_config->lane_count = intel_mst_state->lane_count;
+	pipe_config->port_clock = intel_mst_state->link_rate;
 	pipe_config->pipe_bpp = bpp;
 
-	pipe_config->port_clock = intel_dp_max_link_rate(intel_dp);
-
 	if (drm_dp_mst_port_has_audio(&intel_dp->mst_mgr, connector->port))
 		pipe_config->has_audio = true;
 

@@ -80,7 +87,7 @@ static bool intel_dp_mst_compute_config(struct intel_encoder *encoder,
 		return false;
 	}
 
-	intel_link_compute_m_n(bpp, lane_count,
+	intel_link_compute_m_n(bpp, intel_mst_state->lane_count,
 			       adjusted_mode->crtc_clock,
 			       pipe_config->port_clock,
 			       &pipe_config->dp_m_n,

@@ -530,11 +537,55 @@ static void intel_dp_mst_hotplug(struct drm_dp_mst_topology_mgr *mgr)
 	drm_kms_helper_hotplug_event(dev);
 }
 
+static void intel_mst_reset_state(struct drm_dp_mst_topology_state *state)
+{
+	struct intel_dp_mst_topology_state *intel_mst_state =
+		to_intel_dp_mst_topology_state(state);
+
+	intel_mst_state->link_rate = 0;
+	intel_mst_state->lane_count = 0;
+}
+
 static const struct drm_dp_mst_topology_cbs mst_cbs = {
 	.add_connector = intel_dp_add_mst_connector,
 	.register_connector = intel_dp_register_mst_connector,
 	.destroy_connector = intel_dp_destroy_mst_connector,
 	.hotplug = intel_dp_mst_hotplug,
+	.reset_state = intel_mst_reset_state,
+};
+
+static struct drm_private_state *
+intel_dp_mst_duplicate_state(struct drm_private_obj *obj)
+{
+	struct intel_dp_mst_topology_state *state;
+	struct drm_dp_mst_topology_mgr *mgr = to_dp_mst_topology_mgr(obj);
+
+	state = kmemdup(obj->state, sizeof(*state), GFP_KERNEL);
+	if (!state)
+		return NULL;
+
+	__drm_atomic_dp_mst_duplicate_topology_state(mgr, &state->base);
+
+	return &state->base.base;
+}
+
+static void
+intel_dp_mst_destroy_state(struct drm_private_obj *obj,
+			   struct drm_private_state *state)
+{
+	struct drm_dp_mst_topology_state *mst_state =
+		to_dp_mst_topology_state(state);
+	struct intel_dp_mst_topology_state *intel_mst_state =
+		to_intel_dp_mst_topology_state(mst_state);
+
+	__drm_atomic_dp_mst_destroy_topology_state(mst_state);
+
+	kfree(intel_mst_state);
+}
+
+static const struct drm_private_state_funcs mst_state_funcs = {
+	.atomic_duplicate_state = intel_dp_mst_duplicate_state,
+	.atomic_destroy_state = intel_dp_mst_destroy_state,
 };
 
 static struct intel_dp_mst_encoder *

@@ -587,21 +638,16 @@ intel_dp_create_fake_mst_encoders(struct intel_digital_port *intel_dig_port)
 	return true;
 }
 
-static const struct drm_private_state_funcs mst_state_funcs = {
-	.atomic_destroy_state = drm_atomic_dp_mst_destroy_topology_state,
-	.atomic_duplicate_state = drm_atomic_dp_mst_duplicate_topology_state,
-};
-
 int
 intel_dp_mst_encoder_init(struct intel_digital_port *intel_dig_port, int conn_base_id)
 {
 	struct intel_dp *intel_dp = &intel_dig_port->dp;
-	struct drm_dp_mst_topology_state *mst_state;
+	struct intel_dp_mst_topology_state *intel_mst_state;
 	struct drm_device *dev = intel_dig_port->base.base.dev;
 	int ret;
 
-	mst_state = kzalloc(sizeof(*mst_state), GFP_KERNEL);
-	if (!mst_state)
+	intel_mst_state = kzalloc(sizeof(*intel_mst_state), GFP_KERNEL);
+	if (!intel_mst_state)
 		return -ENOMEM;
 
 	intel_dp->can_mst = true;

@@ -610,7 +656,8 @@ intel_dp_mst_encoder_init(struct intel_digital_port *intel_dig_port, int conn_ba
 
 	/* create encoders */
 	intel_dp_create_fake_mst_encoders(intel_dig_port);
-	ret = drm_dp_mst_topology_mgr_init(&intel_dp->mst_mgr, mst_state, dev,
+	ret = drm_dp_mst_topology_mgr_init(&intel_dp->mst_mgr,
+					   &intel_mst_state->base, dev,
 					   &intel_dp->aux, 16, 3, conn_base_id);
 	if (ret) {
 		intel_dp->can_mst = false;

index 742d53495974..eccb4bd042c3 100644
@@ -985,6 +985,12 @@ struct cxsr_latency {
 	u16 cursor_hpll_disable;
 };
 
+struct intel_dp_mst_topology_state {
+	struct drm_dp_mst_topology_state base;
+	int link_rate;
+	int lane_count;
+};
+
 #define to_intel_atomic_state(x) container_of(x, struct intel_atomic_state, base)
 #define to_intel_crtc(x) container_of(x, struct intel_crtc, base)
 #define to_intel_crtc_state(x) container_of(x, struct intel_crtc_state, base)

@@ -993,6 +999,7 @@ struct cxsr_latency {
 #define to_intel_framebuffer(x) container_of(x, struct intel_framebuffer, base)
 #define to_intel_plane(x) container_of(x, struct intel_plane, base)
 #define to_intel_plane_state(x) container_of(x, struct intel_plane_state, base)
+#define to_intel_dp_mst_topology_state(x) container_of(x, struct intel_dp_mst_topology_state, base)
 #define intel_fb_obj(x) (x ? to_intel_framebuffer(x)->obj : NULL)
 
 struct intel_hdmi {

index 19de0b5a7a40..31b37722cd89 100644
@@ -30,6 +30,38 @@
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_edid.h>
 
+static int
+intel_dp_mst_atomic_release_vcpi_slots(struct drm_atomic_state *state,
+				       struct drm_crtc_state *crtc_state,
+				       struct drm_connector_state *conn_state)
+{
+	struct drm_crtc_state *new_crtc_state;
+	struct intel_crtc_state *intel_crtc_state =
+		to_intel_crtc_state(crtc_state);
+	struct drm_encoder *encoder;
+	struct drm_dp_mst_topology_mgr *mgr;
+	int slots, ret;
+
+	slots = intel_crtc_state->dp_m_n.tu;
+	if (slots <= 0)
+		return 0;
+
+	encoder = conn_state->best_encoder;
+	mgr = &enc_to_mst(encoder)->primary->dp.mst_mgr;
+
+	ret = drm_dp_atomic_release_vcpi_slots(state, mgr, slots);
+	if (ret) {
+		DRM_DEBUG_KMS("failed releasing %d vcpi slots:%d\n",
+			      slots, ret);
+	} else {
+		new_crtc_state = drm_atomic_get_crtc_state(state,
+							   crtc_state->crtc);
+		to_intel_crtc_state(new_crtc_state)->dp_m_n.tu = 0;
+	}
+
+	return ret;
+}
+
 static bool intel_dp_mst_compute_config(struct intel_encoder *encoder,
 					struct intel_crtc_state *pipe_config,
 					struct drm_connector_state *conn_state)

@@ -44,10 +76,14 @@ static bool intel_dp_mst_compute_config(struct intel_encoder *encoder,
 	struct drm_dp_mst_topology_state *mst_state =
 		drm_atomic_dp_mst_get_topology_state(state, &intel_dp->mst_mgr);
 	struct intel_dp_mst_topology_state *intel_mst_state;
+	struct drm_connector_state *old_conn_state =
+		drm_atomic_get_old_connector_state(state, &connector->base);
+	struct drm_crtc *old_crtc;
 	int bpp;
 	int slots;
 	const struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode;
 	int mst_pbn;
+	int ret;
 	bool reduce_m_n = drm_dp_has_quirk(&intel_dp->desc,
 					   DP_DPCD_QUIRK_LIMITED_M_N);
 

@@ -80,6 +116,21 @@ static bool intel_dp_mst_compute_config(struct intel_encoder *encoder,
 	mst_pbn = drm_dp_calc_pbn_mode(adjusted_mode->crtc_clock, bpp);
 	pipe_config->pbn = mst_pbn;
 
+	/* Free any VCPI allocations on this connector from the previous
+	 * state
+	 */
+	old_crtc = old_conn_state->crtc;
+	if (old_crtc) {
+		struct drm_crtc_state *old_crtc_state =
+			drm_atomic_get_old_crtc_state(state, old_crtc);
+
+		ret = intel_dp_mst_atomic_release_vcpi_slots(state,
+							     old_crtc_state,
+							     old_conn_state);
+		if (ret)
+			return ret;
+	}
+
 	slots = drm_dp_atomic_find_vcpi_slots(state, &intel_dp->mst_mgr,
 					      connector->port, mst_pbn);
 	if (slots < 0) {

@@ -109,31 +160,22 @@ static int intel_dp_mst_atomic_check(struct drm_connector *connector,
 {
 	struct drm_atomic_state *state = new_conn_state->state;
 	struct drm_connector_state *old_conn_state;
-	struct drm_crtc *old_crtc;
-	struct drm_crtc_state *crtc_state;
-	int slots, ret = 0;
+	struct drm_crtc_state *new_crtc_state;
+	int ret = 0;
 
 	old_conn_state = drm_atomic_get_old_connector_state(state, connector);
-	old_crtc = old_conn_state->crtc;
-	if (!old_crtc)
-		return ret;
 
-	crtc_state = drm_atomic_get_new_crtc_state(state, old_crtc);
-	slots = to_intel_crtc_state(crtc_state)->dp_m_n.tu;
-	if (drm_atomic_crtc_needs_modeset(crtc_state) && slots > 0) {
-		struct drm_dp_mst_topology_mgr *mgr;
-		struct drm_encoder *old_encoder;
-
-		old_encoder = old_conn_state->best_encoder;
-		mgr = &enc_to_mst(old_encoder)->primary->dp.mst_mgr;
+	/* Only free VCPI here if we're not going to be detaching the
+	 * connector's current CRTC, since no config will be computed
+	 */
+	if (new_conn_state->crtc || !old_conn_state->crtc)
+		return ret;
 
-		ret = drm_dp_atomic_release_vcpi_slots(state, mgr, slots);
-		if (ret)
-			DRM_DEBUG_KMS("failed releasing %d vcpi slots:%d\n", slots, ret);
-		else
-			to_intel_crtc_state(crtc_state)->dp_m_n.tu = 0;
-	}
-	return ret;
+	new_crtc_state = drm_atomic_get_new_crtc_state(state,
+						       old_conn_state->crtc);
+	return intel_dp_mst_atomic_release_vcpi_slots(state,
+						      new_crtc_state,
+						      old_conn_state);
 }
 
 static void intel_mst_disable_dp(struct intel_encoder *encoder,

index 981bd0f7d3ab..cc4b737a47b0 100644
@@ -1199,6 +1199,7 @@ static void drm_dp_add_port(struct drm_dp_mst_branch *mstb,
 
 	if (created && !port->input) {
 		char proppath[255];
+		struct drm_dp_mst_topology_state *state;
 
 		build_mst_prop_path(mstb, port->port_num, proppath, sizeof(proppath));
 		port->connector = (*mstb->mgr->cbs->add_connector)(mstb->mgr, port, proppath);

@@ -1217,6 +1218,11 @@ static void drm_dp_add_port(struct drm_dp_mst_branch *mstb,
 			port->cached_edid = drm_get_edid(port->connector, &port->aux.ddc);
 			drm_mode_connector_set_tile_property(port->connector);
 		}
+		state = to_dp_mst_topology_state(port->mgr->base.state);
+		if (!list_empty(&state->bad_ports)) {
+			port->connector->state->link_status =
+				DRM_LINK_STATUS_BAD;
+		}
 		(*mstb->mgr->cbs->register_connector)(port->connector);
 	}
 

@@ -2076,7 +2082,7 @@ static bool drm_dp_get_vc_payload_bw(int dp_link_bw,
 {
 	switch (dp_link_bw) {
 	default:
-		DRM_DEBUG_KMS("invalid link bandwidth in DPCD: %x (link count: %d)\n",
+		DRM_DEBUG_KMS("invalid link bandwidth: %x (link count: %d)\n",
 			      dp_link_bw, dp_link_count);
 		return false;
 

@@ -2096,10 +2102,409 @@ static bool drm_dp_get_vc_payload_bw(int dp_link_bw,
 	return true;
 }
 
+static int drm_dp_set_mstb_link_status(struct drm_dp_mst_topology_mgr *mgr,
+				       struct drm_dp_mst_branch *mstb,
+				       enum drm_link_status status)
+{
+	struct drm_dp_mst_topology_state *state =
+		to_dp_mst_topology_state(mgr->base.state);
+	struct drm_dp_mst_branch *rmstb;
+	struct drm_dp_mst_port *port;
+	struct drm_connector *connector;
+	struct drm_dp_mst_retrain_dep *retrain_dep;
+	int ret;
+
+	list_for_each_entry(port, &mstb->ports, next) {
+		rmstb = drm_dp_get_validated_mstb_ref(mgr, port->mstb);
+		if (rmstb) {
+			ret = drm_dp_set_mstb_link_status(mgr, rmstb, status);
+			drm_dp_put_mst_branch_device(rmstb);
+
+			if (ret)
+				return ret;
+		}
+
+		connector = port->connector;
+		if (!connector)
+			continue;
+
+		DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] link status good -> bad\n",
+				 connector->base.id, connector->name);
+		connector->state->link_status = status;
+
+		if (!connector->state->crtc)
+			continue;
+
+		retrain_dep = kmalloc(sizeof(*retrain_dep), GFP_KERNEL);
+		if (!retrain_dep) {
+			DRM_ERROR("Not enough memory to update atomic state\n");
+			return -ENOMEM;
+		}
+
+		retrain_dep->connector = connector;
+		drm_connector_get(connector);
+		list_add(&retrain_dep->entry, &state->bad_ports);
+	}
+
+	return 0;
+}
+
+static void drm_dp_mst_destroy_retrain_dep(struct drm_dp_mst_retrain_dep *dep)
+{
+	drm_connector_put(dep->connector);
+	list_del(&dep->entry);
+	kfree(dep);
+}
+
+/**
+ * DOC: handling link retraining on MST topologies
+ *
+ * DisplayPort MST hubs work by allowing multiple connections on a single
+ * physical DisplayPort link. Because of this, any changes in the link status
+ * affect all connectors on the shared link. This has quite a number of
+ * important implications.
+ *
+ * When an MST topology requires that it be retrained at a lower link rate,
+ * the new link rate must be applied to all active connectors at the same
+ * time, since they share the same link. This means that if a connector has
+ * it's link status set to &DRM_MODE_LINK_STATUS_BAD and it's on an MST
+ * topology, changing the property to &DRM_MODE_LINK_STATUS_GOOD will result
+ * in adding every other connector that resides on the same topology into the
+ * new atomic state. Additionally, any MST connectors that were added to the
+ * state with CRTCs attached to them will automatically have a modeset forced
+ * on them in the atomic state, and have their link status updated to
+ * &DRM_MODE_LINK_STATUS_GOOD. If userspace has not set a new mode on these
+ * connectors, the kernel will attempt to reuse the same modes that are
+ * currently active on said CRTCs. All modes set on said connectors within
+ * this state are then checked against the new lowered link configuration to
+ * ensure that there is still enough bandwidth to support them. If there is
+ * not enough bandwidth, the atomic check will fail.
+ *
+ * Detaching CRTCs from MST connectors that have their link status set to
+ * &DRM_MODE_LINK_STATUS_BAD has a different effect however. Because disabling
+ * a CRTC on an MST connector only requires that the driver free the bandwidth
+ * allocated to a connector and does not require the driver to allocate more
+ * bandwidth, states which disable CRTCs on an MST topology but do not enable
+ * new CRTCs or apply new modes to CRTCs on the topology will not implicitly
+ * pull in the state of other CRTCs attached to connectors on the topology.
+ * This allows userspace to disable CRTCs on a topology that requires
+ * retraining in any order it chooses, so long as it doesn't try to apply new
+ * modes to the topology.
+ *
+ * If an atomic state would put an MST topology into a state where it has no
+ * connectors present that are attached to CRTCs, the kernel will
+ * automatically add each connector on the topology to the state and update
+ * their respective link statuses to &DRM_MODE_LINK_STATUS_GOOD. This is
+ * because when there are no active VC channels allocated on a hub, there is
+ * nothing which prevents the driver from immediately changing the maximum
+ * link rate/lane count, as the updated link configuration can simply be
+ * applied the next time a CRTC is attached to a connector on the topology.
+ *
+ * When an MST topology requires link retraining at a lower link rate, any new
+ * connectors that appear on the topology will automatically inherit the link
+ * status value of other connectors on the topology. This is to ensure that
+ * the shared link status remains consistent across the topology, and to
+ * prevent new modesets from occurring on the topology without first requiring
+ * a full retrain.
+ */
+
+/**
+ * drm_dp_mst_topology_mgr_lower_link_rate() - Override the DP link rate/count
+ * for all connectors in a given MST topology
+ * @mgr: manager to set state for
+ * @link_rate: The new DP link bandwidth
+ * @lane_count: The new DP lane count
+ *
+ * This is called by the driver when it detects that the current DP link for
+ * the given topology manager is unstable, and needs to be retrained at a
+ * lower link rate/lane count.
+ *
+ * This takes care of updating the link status on all downstream connectors,
+ * the mst topology's atomic state, and VC payloads for each port.
+ * The driver should send a hotplug event after calling this function to
+ * notify userspace of the link status change.
+ *
+ * RETURNS:
+ *
+ * True for success, or negative error code on failure.
+ */
+int drm_dp_mst_topology_mgr_lower_link_rate(struct drm_dp_mst_topology_mgr *mgr,
+					    int link_rate, int lane_count)
+{
+	struct drm_device *dev = mgr->dev;
+	struct drm_dp_mst_topology_state *state;
+	struct drm_dp_mst_branch *mst_primary;
+	struct drm_dp_mst_retrain_dep *retrain_dep, *retrain_tmp;
+	struct drm_connector *connector;
+	int new_pbn_div;
+	int ret = 0;
+
+	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
+
+	state = to_dp_mst_topology_state(mgr->base.state);
+
+	if (!drm_dp_get_vc_payload_bw(drm_dp_link_rate_to_bw_code(link_rate),
+				      lane_count, &new_pbn_div)) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	mst_primary = drm_dp_get_validated_mstb_ref(mgr, mgr->mst_primary);
+	if (!mst_primary)
+		goto out;
+
+	DRM_DEBUG_KMS("MST link impossible to retrain at current params, lowering pbn_div to %d\n",
+		      new_pbn_div);
+	mgr->pbn_div = new_pbn_div;
+
+	ret = drm_dp_set_mstb_link_status(mgr, mst_primary,
+					  DRM_LINK_STATUS_BAD);
+	if (ret) {
+		DRM_DEBUG_KMS("Failed to update link status, rolling back\n");
+
+		list_for_each_entry_safe(retrain_dep, retrain_tmp,
+					 &state->bad_ports, entry) {
+			connector = retrain_dep->connector;
+			connector->state->link_status = DRM_LINK_STATUS_GOOD;
+
+			drm_dp_mst_destroy_retrain_dep(retrain_dep);
+		}
+	}
+
+	drm_dp_put_mst_branch_device(mst_primary);
+out:
+	drm_modeset_unlock(&dev->mode_config.connection_mutex);
+	return ret;
+}
+EXPORT_SYMBOL(drm_dp_mst_topology_mgr_lower_link_rate);
+
+static void
+drm_atomic_dp_mst_satisfy_retrain_dep(struct drm_dp_mst_topology_state *mst_state,
+				      struct drm_connector *connector)
+{
+	struct drm_dp_mst_retrain_dep *dep;
+
+	list_for_each_entry(dep, &mst_state->bad_ports, entry) {
+		if (dep->connector != connector)
+			continue;
+
+		drm_dp_mst_destroy_retrain_dep(dep);
+		break;
+	}
+}
+
+static int
+drm_atomic_dp_mst_retrain_connector(struct drm_atomic_state *state,
+				    struct drm_dp_mst_topology_state *mst_state,
+				    struct drm_connector *connector)
+{
+	struct drm_connector_state *conn_state =
+		drm_atomic_get_connector_state(state, connector);
+	struct drm_crtc *crtc;
+	struct drm_crtc_state *crtc_state;
+
+	if (IS_ERR(conn_state))
+		return PTR_ERR(conn_state);
+
+	if (conn_state->link_status == DRM_LINK_STATUS_BAD) {
+		DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] link status bad -> good\n",
+				 connector->base.id, connector->name);
+		conn_state->link_status = DRM_LINK_STATUS_GOOD;
+	}
+
+	drm_atomic_dp_mst_satisfy_retrain_dep(mst_state, connector);
+
+	crtc = conn_state->crtc;
+	if (!crtc)
+		return 0;
+
+	crtc_state = drm_atomic_get_crtc_state(state, crtc);
+	if (IS_ERR(crtc_state))
+		return PTR_ERR(crtc_state);
+
+	if (!drm_atomic_crtc_needs_modeset(crtc_state))
+		DRM_DEBUG_ATOMIC("[CRTC:%d:%s] needs full modeset\n",
+				 crtc->base.id, crtc->name);
+
+	crtc_state->mode_changed = true;
+	return 0;
+}
+
+static int
+drm_atomic_dp_mst_retrain_mstb(struct drm_atomic_state *state,
+			       struct drm_dp_mst_topology_state *mst_state,
+			       struct drm_dp_mst_branch *mstb)
+{
+	struct drm_dp_mst_branch *rmstb;
+	struct drm_dp_mst_port *port;
+	struct drm_connector *connector;
+	int ret;
+
+	list_for_each_entry(port, &mstb->ports, next) {
+		rmstb = drm_dp_get_validated_mstb_ref(mstb->mgr, port->mstb);
+		if (rmstb) {
+			ret = drm_atomic_dp_mst_retrain_mstb(state, mst_state,
+							     rmstb);
+			drm_dp_put_mst_branch_device(rmstb);
+			if (ret)
+				return ret;
+		}
+
+		connector = port->connector;
+		if (!connector)
+			continue;
+
+		ret = drm_atomic_dp_mst_retrain_connector(state, mst_state,
+							  connector);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+/**
+ * drm_dp_atomic_mst_check_retrain() - Prepare the topology's state to be
+ * retrained during this atomic commit, if required
+ * @new_conn_state: the new connector state possibly triggering a retrain
+ * @mgr: The DP MST topology to retrain
+ *
+ * When the link status of an MST topology goes from
+ * &DRM_MODE_LINK_STATUS_GOOD to &DRM_MODE_LINK_STATUS_BAD, the entire
+ * topology is considered to be in a state where a retrain at a lower link
+ * rate is required. Because each connector on an MST topology shares the same
+ * DP link, each connector must have it's link rate lowered and be retrained
+ * at the same time. Additionally, drivers must take care to update the link
+ * status of a connector on an MST topology themselves if userspace attempts
+ * to set a new mode to the connector regardless of whether or not it properly
+ * updates the connector's link status property from
+ * &DRM_MODE_LINK_STATUS_BAD to &DRM_MODE_LINK_STATUS_GOOD. In this case, the
+ * driver must take care of updating this link status property on it's own.
+ *
+ * This function takes care of handling all of the above requirements, and
+ * should be called during the start of the atomic check phase for an MST
+ * connector if the driver properly implements MST fallback retraining.
+ *
+ * Additionally; drivers are recommended to check the return value of this
+ * function in order to determine whether or not a full retrain of the MST
+ * topology would be performed by the new atomic state. This gives the
+ * driver a chance to update any private portions of the topology state that
+ * must be reset before a retrain, such as the link rate and lane count being
+ * shared by the topology.
+ *
+ * RETURNS: 1 if the given atomic state retrains the MST topology, 0 if the
+ * atomic state doesn't retrain the topology. On error, a negative error code
+ * is returned.
+ */
+int drm_dp_atomic_mst_check_retrain(struct drm_connector_state *new_conn_state,
+				    struct drm_dp_mst_topology_mgr *mgr)
+{
+	struct drm_atomic_state *state = new_conn_state->state;
+	struct drm_dp_mst_topology_state *mst_state;
+	struct drm_dp_mst_branch *mstb;
+	struct drm_dp_mst_retrain_dep *retrain_dep, *retrain_tmp;
+	struct drm_connector *connector = new_conn_state->connector;
+	struct drm_connector_state *old_conn_state =
+		drm_atomic_get_old_connector_state(state, connector);
+	struct drm_crtc_state *crtc_state;
+	struct drm_crtc *crtc;
+	int ret;
+
+	if (old_conn_state->link_status != DRM_LINK_STATUS_BAD)
+		return 0;
+
+	mst_state = drm_atomic_dp_mst_get_topology_state(state, mgr);
+	if (list_empty(&mst_state->bad_ports))
+		return 0;
+
+	/* Check if the new state requires us to update the link status
+	 * prop
+	 */
+	if (new_conn_state->link_status == DRM_LINK_STATUS_BAD) {
+		/* Any modesets that leave a CRTC enabled must update link
+		 * status
+		 */
+		if (new_conn_state->crtc) {
+			crtc = new_conn_state->crtc;
+			crtc_state = drm_atomic_get_new_crtc_state(state,
+								   crtc);
+			if (crtc_state &&
+			    drm_atomic_crtc_needs_modeset(crtc_state)) {
+				DRM_DEBUG_ATOMIC("[CRTC:%d:%s] modeset requires link retrain\n",
+						 crtc->base.id, crtc->name);
+				new_conn_state->link_status =
+					DRM_LINK_STATUS_GOOD;
+			}
+		} else if (old_conn_state->crtc) {
+			drm_atomic_dp_mst_satisfy_retrain_dep(mst_state,
+							      connector);
+			/* If all CRTCs on this hub would be disabled by this
+			 * state, link status can be updated to GOOD
+			 */
+			if (list_empty(&mst_state->bad_ports)) {
+				DRM_DEBUG_ATOMIC("state %p disables all CRTCs on %p, link would be retrained\n",
+						 state, mgr);
+				new_conn_state->link_status =
+					DRM_LINK_STATUS_GOOD;
+			}
+		}
+		if (new_conn_state->link_status == DRM_LINK_STATUS_BAD)
+			return 0;
+	}
+
+	DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] link status bad -> good\n",
+			 connector->base.id, connector->name);
+	ret = drm_atomic_dp_mst_retrain_connector(state, mst_state,
+						  connector);
+	if (ret)
+		return ret;
+
+	/* Retrain whole topology */
+	mstb = drm_dp_get_validated_mstb_ref(mgr, mgr->mst_primary);
+	if (!mstb)
+		return -EIO;
+	ret = drm_atomic_dp_mst_retrain_mstb(state, mst_state, mstb);
+	drm_dp_put_mst_branch_device(mstb);
+	if (ret)
+		return ret;
+
+	/* Additionally, it's possible that the topology connector state may
+	 * have changed between the time the topology's link status went to
+	 * BAD. As a result, it's possible that there's still leftover retrain
+	 * dependencies that refer to connectors that no longer exist on the
+	 * hub. Ensure these are added to the state as well
+	 */
+	list_for_each_entry_safe(retrain_dep, retrain_tmp,
+				 &mst_state->bad_ports, entry) {
+		ret = drm_atomic_dp_mst_retrain_connector(state, mst_state,
+							  connector);
+		if (ret)
+			return ret;
+	}
+
+	return 1;
+}
+EXPORT_SYMBOL(drm_dp_atomic_mst_check_retrain);
+
 static void drm_dp_mst_topology_reset_state(struct drm_dp_mst_topology_mgr *mgr)
 {
+	struct drm_dp_mst_retrain_dep *retrain_dep, *retrain_tmp;
 	struct drm_dp_mst_topology_state *state =
 		to_dp_mst_topology_state(mgr->base.state);
+	struct drm_connector *connector;
+
+	list_for_each_entry_safe(retrain_dep, retrain_tmp, &state->bad_ports,
+				 entry) {
+		/* Reset the connector link state, since there's no way to
+		 * retrain something that no longer exists
+		 */
+		connector = retrain_dep->connector;
+
+		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] loses parent MST topology mgr %p, link status bad -> good\n",
+			      connector->base.id, connector->name, mgr);
+		connector->state->link_status = DRM_LINK_STATUS_GOOD;
+		drm_dp_mst_destroy_retrain_dep(retrain_dep);
+	}
 
 	if (mgr->cbs->reset_state)
 		mgr->cbs->reset_state(state);

@@ -3110,7 +3515,7 @@ static void drm_dp_destroy_connector_work(struct work_struct *work)
 		(*mgr->cbs->hotplug)(mgr);
 }
 
-/**
+/*
  * drm_atomic_dp_mst_duplicate_topology_state - default
  * drm_dp_mst_topology_state duplicate handler
  *

@@ -3153,9 +3558,26 @@ int
 __drm_atomic_dp_mst_duplicate_topology_state(struct drm_dp_mst_topology_mgr *mgr,
 					     struct drm_dp_mst_topology_state *state)
 {
+	struct drm_dp_mst_retrain_dep *retrain_dep, *new_retrain_dep;
 	struct drm_private_obj *obj = &mgr->base;
+	struct drm_dp_mst_topology_state *src_state =
+		to_dp_mst_topology_state(obj->state);
 
 	memcpy(state, obj->state, sizeof(*state));
+	INIT_LIST_HEAD(&state->bad_ports);
+
+	/* Copy the bad ports list to the new state */
+	list_for_each_entry(retrain_dep, &src_state->bad_ports, entry) {
+		new_retrain_dep = kmalloc(sizeof(*retrain_dep), GFP_KERNEL);
+		if (!new_retrain_dep) {
+			__drm_atomic_dp_mst_destroy_topology_state(state);
+			return -ENOMEM;
+		}
+
+		new_retrain_dep->connector = retrain_dep->connector;
+		drm_connector_get(retrain_dep->connector);
+		list_add(&new_retrain_dep->entry, &state->bad_ports);
+	}
 
 	__drm_atomic_helper_private_obj_duplicate_state(&mgr->base,
 							&state->base);

@@ -3169,9 +3591,8 @@ EXPORT_SYMBOL(__drm_atomic_dp_mst_duplicate_topology_state);
  *
  * For drivers which don't yet subclass drm_dp_mst_topology_state.
  */
-void
-drm_atomic_dp_mst_destroy_topology_state(struct drm_private_obj *obj,
-					 struct drm_private_state *state)
+void drm_atomic_dp_mst_destroy_topology_state(struct drm_private_obj *obj,
+					      struct drm_private_state *state)
 {
 	struct drm_dp_mst_topology_state *mst_state =
 		to_dp_mst_topology_state(state);

@@ -3192,6 +3613,13 @@ EXPORT_SYMBOL(drm_atomic_dp_mst_destroy_topology_state);
 void
 __drm_atomic_dp_mst_destroy_topology_state(struct drm_dp_mst_topology_state *state)
 {
+	struct drm_dp_mst_retrain_dep *retrain_dep, *retrain_tmp;
+
+	list_for_each_entry_safe(retrain_dep, retrain_tmp, &state->bad_ports,
+				 entry) {
+		drm_connector_put(retrain_dep->connector);
+		kfree(retrain_dep);
+	}
 }
 EXPORT_SYMBOL(__drm_atomic_dp_mst_destroy_topology_state);
 

@@ -3276,6 +3704,8 @@ int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
 	/* max. time slots - one slot for MTP header */
 	state->avail_slots = 63;
 
+	INIT_LIST_HEAD(&state->bad_ports);
+
 	drm_atomic_private_obj_init(&mgr->base,
 				    &state->base,
 				    mgr->funcs);

index 3a7378cd5bd1..32f6944de560 100644
@@ -407,9 +407,24 @@ struct drm_dp_payload {
 
 #define to_dp_mst_topology_state(x) container_of(x, struct drm_dp_mst_topology_state, base)
 
+/* Represents a connector with an MST port whose mstb had a mode programmed
+ * when the link rate of the topology was lowered. As long as a topology state
+ * has these, no mstbs may be activated
+ */
+struct drm_dp_mst_retrain_dep {
+	struct drm_connector *connector;
+	struct list_head entry;
+};
+
 struct drm_dp_mst_topology_state {
 	struct drm_private_state base;
 	int avail_slots;
+	/**
+	 * @bad_ports: DRM connectors that must have their mode changed before
+	 * the link status of each connector on the MST hub can be updated
+	 * from BAD to GOOD
+	 */
+	struct list_head bad_ports;
 	struct drm_dp_mst_topology_mgr *mgr;
 };
 

@@ -639,4 +654,9 @@ int drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,
 int drm_dp_send_power_updown_phy(struct drm_dp_mst_topology_mgr *mgr,
 				 struct drm_dp_mst_port *port, bool power_up);
 
+int drm_dp_mst_topology_mgr_lower_link_rate(struct drm_dp_mst_topology_mgr *mgr,
+					    int link_rate, int lane_count);
+int drm_dp_atomic_mst_check_retrain(struct drm_connector_state *new_conn_state,
+				    struct drm_dp_mst_topology_mgr *mgr);
+
 #endif

index 92cb26b18a9b..7474300cad01 100644
@@ -3042,6 +3042,7 @@ static bool intel_ddi_hotplug(struct intel_encoder *encoder,
 			      struct intel_connector *connector)
 {
 	struct drm_modeset_acquire_ctx ctx;
+	struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
 	bool changed;
 	int ret;
 

@@ -3063,9 +3064,16 @@ static bool intel_ddi_hotplug(struct intel_encoder *encoder,
 		break;
 	}
 
+	if (ret == -EINVAL)
+		ret = intel_dp_handle_train_failure(intel_dp);
+
 	drm_modeset_drop_locks(&ctx);
 	drm_modeset_acquire_fini(&ctx);
-	WARN(ret, "Acquiring modeset locks failed with %i\n", ret);
+
+	if (ret == -EIO)
+		changed = true;
+	else
+		WARN(ret, "Acquiring modeset locks failed with %i\n", ret);
 
 	return changed;
 }

499 lines not on this page · raw message

index 2cfa58ce1f95..aa6cfccdab0f 100644
@@ -336,11 +336,7 @@ intel_dp_start_link_train(struct intel_dp *intel_dp)
 			      intel_connector->base.base.id,
 			      intel_connector->base.name,
 			      intel_dp->link_rate, intel_dp->lane_count);
-		if (!intel_dp_get_link_train_fallback_values(intel_dp,
-							     intel_dp->link_rate,
-							     intel_dp->lane_count))
-			/* Schedule a Hotplug Uevent to userspace to start modeset */
-			schedule_work(&intel_dp->modeset_retry_work);
+		intel_dp_handle_train_failure(intel_dp);
 	} else {
 		DRM_ERROR("[CONNECTOR:%d:%s] Link Training failed at link rate = %d, lane count = %d",
 			  intel_connector->base.base.id,

index 31b37722cd89..f61950073f05 100644
@@ -156,13 +156,37 @@ static bool intel_dp_mst_compute_config(struct intel_encoder *encoder,
 }
 
 static int intel_dp_mst_atomic_check(struct drm_connector *connector,
-		struct drm_connector_state *new_conn_state)
+				     struct drm_connector_state *new_conn_state)
 {
 	struct drm_atomic_state *state = new_conn_state->state;
 	struct drm_connector_state *old_conn_state;
 	struct drm_crtc_state *new_crtc_state;
+	struct intel_dp *intel_dp = to_intel_connector(connector)->mst_port;
+	struct drm_dp_mst_topology_state *mst_state;
+	struct intel_dp_mst_topology_state *intel_mst_state;
 	int ret = 0;
 
+	/* We can't retrain anything if the hub isn't there anymore */
+	if (intel_dp) {
+		ret = drm_dp_atomic_mst_check_retrain(new_conn_state,
+						      &intel_dp->mst_mgr);
+
+		/* This commit invokes a retrain, reset the link rate */
+		if (ret == 1) {
+			mst_state =
+				drm_atomic_dp_mst_get_topology_state(state,
+								     &intel_dp->mst_mgr);
+			intel_mst_state =
+				to_intel_dp_mst_topology_state(mst_state);
+
+			intel_mst_state->link_rate = 0;
+			intel_mst_state->lane_count = 0;
+			ret = 0;
+		} else if (ret < 0) {
+			return ret;
+		}
+	}
+
 	old_conn_state = drm_atomic_get_old_connector_state(state, connector);
 
 	/* Only free VCPI here if we're not going to be detaching the

@@ -230,7 +254,9 @@ static void intel_mst_post_disable_dp(struct intel_encoder *encoder,
 
 	intel_mst->connector = NULL;
 	if (intel_dp->active_mst_links == 0) {
+		intel_dp->link_is_bad = false;
 		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
+
 		intel_dig_port->base.post_disable(&intel_dig_port->base,
 						  old_crtc_state, NULL);
 	}

index eccb4bd042c3..9567a0e71424 100644
@@ -1128,6 +1128,11 @@ struct intel_dp {
 	/* mst connector list */
 	struct intel_dp_mst_encoder *mst_encoders[I915_MAX_PIPES];
 	struct drm_dp_mst_topology_mgr mst_mgr;
+	struct completion mst_retrain_completion;
+	/* Set when retraining the link at the current parameters is
+	 * impossible
+	 */
+	bool link_is_bad;
 
 	uint32_t (*get_aux_clock_divider)(struct intel_dp *dp, int index);
 	/*

@@ -1649,6 +1654,7 @@ void intel_dp_start_link_train(struct intel_dp *intel_dp);
 void intel_dp_stop_link_train(struct intel_dp *intel_dp);
 int intel_dp_retrain_link(struct intel_encoder *encoder,
 			  struct drm_modeset_acquire_ctx *ctx);
+int intel_dp_handle_train_failure(struct intel_dp *intel_dp);
 void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode);
 void intel_dp_encoder_reset(struct drm_encoder *encoder);
 void intel_dp_encoder_suspend(struct intel_encoder *intel_encoder);

@@ -1701,6 +1707,7 @@ void intel_dp_compute_rate(struct intel_dp *intel_dp, int port_clock,
 bool intel_dp_source_supports_hbr2(struct intel_dp *intel_dp);
 bool
 intel_dp_get_link_status(struct intel_dp *intel_dp, uint8_t link_status[DP_LINK_STATUS_SIZE]);
+int intel_dp_get_crtc_mask(struct intel_dp *intel_dp);
 
 static inline unsigned int intel_dp_unused_lane_mask(int lane_count)
 {