Merge tag 'topic/mst-suspend-resume-reprobe-2019-10-29-2' of...

Merge tag 'topic/mst-suspend-resume-reprobe-2019-10-29-2' of git://anongit.freedesktop.org/drm/drm-misc into drm-next

UAPI Changes:

Cross-subsystem Changes:

Core Changes:
* Handle UP requests asynchronously in the DP MST helpers, fixing
  hotplug notifications and allowing us to implement suspend/resume
  reprobing
* Add basic suspend/resume reprobing to the DP MST helpers
* Improve locking for link address reprobing and connection status
  request handling in the DP MST helpers
* Miscellaneous refactoring in the DP MST helpers
* Add a Kconfig option to the DP MST helpers to enable tracking of
  gets/puts for topology references for debugging purposes

Driver Changes:
* nouveau: Resume hotplug interrupts earlier, so that sideband
  messages may be transmitted during resume and thus allow
  suspend/resume reprobing for DP MST to work
* nouveau: Avoid grabbing runtime PM references when handling short DP
  pulses, so that handling sideband messages in resume codepaths with the
  DP MST helpers doesn't deadlock us
* i915, nouveau, amdgpu, radeon: Use detect_ctx for probing MST
  connectors, so that we can grab the topology manager's atomic lock

Note: there's some amdgpu patches that I didn't realize were pushed
upstream already when creating this topic branch. When they fail to
apply, you can just ignore and skip them.
Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/a74c6446bc960190d195a751cb6d8a00a98f3974.camel@redhat.com

drivers/gpu/drm/Kconfig

@@ -93,6 +93,20 @@ config DRM_KMS_FB_HELPER
 	help
 	  FBDEV helpers for KMS drivers.
 
+config DRM_DEBUG_DP_MST_TOPOLOGY_REFS
+        bool "Enable refcount backtrace history in the DP MST helpers"
+        select STACKDEPOT
+        depends on DRM_KMS_HELPER
+        depends on DEBUG_KERNEL
+        depends on EXPERT
+        help
+          Enables debug tracing for topology refs in DRM's DP MST helpers. A
+          history of each topology reference/dereference will be printed to the
+          kernel log once a port or branch device's topology refcount reaches 0.
+
+          This has the potential to use a lot of memory and print some very
+          large kernel messages. If in doubt, say "N".
+
 config DRM_FBDEV_EMULATION
 	bool "Enable legacy fbdev support for your modesetting driver"
 	depends on DRM

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -1028,7 +1028,7 @@ static void s3_handle_mst(struct drm_device *dev, bool suspend)
 		if (suspend) {
 			drm_dp_mst_topology_mgr_suspend(mgr);
 		} else {
-			ret = drm_dp_mst_topology_mgr_resume(mgr);
+			ret = drm_dp_mst_topology_mgr_resume(mgr, true);
 			if (ret < 0) {
 				drm_dp_mst_topology_mgr_set_mst(mgr, false);
 				need_hotplug = true;
@@ -1246,7 +1246,7 @@ static int dm_resume(void *handle)
 	 */
 	amdgpu_dm_irq_resume_early(adev);
 
-	/* On resume we need to  rewrite the MSTM control bits to enable MST*/
+	/* On resume we need to rewrite the MSTM control bits to enable MST*/
 	s3_handle_mst(ddev, false);
 
 	/* Do detection*/

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c

@@ -123,21 +123,6 @@ static ssize_t dm_dp_aux_transfer(struct drm_dp_aux *aux,
 	return result;
 }
 
-static enum drm_connector_status
-dm_dp_mst_detect(struct drm_connector *connector, bool force)
-{
-	struct amdgpu_dm_connector *aconnector = to_amdgpu_dm_connector(connector);
-	struct amdgpu_dm_connector *master = aconnector->mst_port;
-
-	enum drm_connector_status status =
-		drm_dp_mst_detect_port(
-			connector,
-			&master->mst_mgr,
-			aconnector->port);
-
-	return status;
-}
-
 static void
 dm_dp_mst_connector_destroy(struct drm_connector *connector)
 {
@@ -175,7 +160,6 @@ amdgpu_dm_mst_connector_early_unregister(struct drm_connector *connector)
 }
 
 static const struct drm_connector_funcs dm_dp_mst_connector_funcs = {
-	.detect = dm_dp_mst_detect,
 	.fill_modes = drm_helper_probe_single_connector_modes,
 	.destroy = dm_dp_mst_connector_destroy,
 	.reset = amdgpu_dm_connector_funcs_reset,
@@ -250,10 +234,22 @@ dm_mst_atomic_best_encoder(struct drm_connector *connector,
 	return &to_amdgpu_dm_connector(connector)->mst_encoder->base;
 }
 
+static int
+dm_dp_mst_detect(struct drm_connector *connector,
+		 struct drm_modeset_acquire_ctx *ctx, bool force)
+{
+	struct amdgpu_dm_connector *aconnector = to_amdgpu_dm_connector(connector);
+	struct amdgpu_dm_connector *master = aconnector->mst_port;
+
+	return drm_dp_mst_detect_port(connector, ctx, &master->mst_mgr,
+				      aconnector->port);
+}
+
 static const struct drm_connector_helper_funcs dm_dp_mst_connector_helper_funcs = {
 	.get_modes = dm_dp_mst_get_modes,
 	.mode_valid = amdgpu_dm_connector_mode_valid,
 	.atomic_best_encoder = dm_mst_atomic_best_encoder,
+	.detect_ctx = dm_dp_mst_detect,
 };
 
 static void amdgpu_dm_encoder_destroy(struct drm_encoder *encoder)

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

@@ -7625,7 +7625,8 @@ void intel_dp_mst_resume(struct drm_i915_private *dev_priv)
 		if (!intel_dp->can_mst)
 			continue;
 
-		ret = drm_dp_mst_topology_mgr_resume(&intel_dp->mst_mgr);
+		ret = drm_dp_mst_topology_mgr_resume(&intel_dp->mst_mgr,
+						     true);
 		if (ret) {
 			intel_dp->is_mst = false;
 			drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst_mgr,

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

@@ -391,20 +391,7 @@ static int intel_dp_mst_get_ddc_modes(struct drm_connector *connector)
 	return ret;
 }
 
-static enum drm_connector_status
-intel_dp_mst_detect(struct drm_connector *connector, bool force)
-{
-	struct intel_connector *intel_connector = to_intel_connector(connector);
-	struct intel_dp *intel_dp = intel_connector->mst_port;
-
-	if (drm_connector_is_unregistered(connector))
-		return connector_status_disconnected;
-	return drm_dp_mst_detect_port(connector, &intel_dp->mst_mgr,
-				      intel_connector->port);
-}
-
 static const struct drm_connector_funcs intel_dp_mst_connector_funcs = {
-	.detect = intel_dp_mst_detect,
 	.fill_modes = drm_helper_probe_single_connector_modes,
 	.atomic_get_property = intel_digital_connector_atomic_get_property,
 	.atomic_set_property = intel_digital_connector_atomic_set_property,
@@ -465,11 +452,26 @@ static struct drm_encoder *intel_mst_atomic_best_encoder(struct drm_connector *c
 	return &intel_dp->mst_encoders[crtc->pipe]->base.base;
 }
 
+static int
+intel_dp_mst_detect(struct drm_connector *connector,
+		    struct drm_modeset_acquire_ctx *ctx, bool force)
+{
+	struct intel_connector *intel_connector = to_intel_connector(connector);
+	struct intel_dp *intel_dp = intel_connector->mst_port;
+
+	if (drm_connector_is_unregistered(connector))
+		return connector_status_disconnected;
+
+	return drm_dp_mst_detect_port(connector, ctx, &intel_dp->mst_mgr,
+				      intel_connector->port);
+}
+
 static const struct drm_connector_helper_funcs intel_dp_mst_connector_helper_funcs = {
 	.get_modes = intel_dp_mst_get_modes,
 	.mode_valid = intel_dp_mst_mode_valid,
 	.atomic_best_encoder = intel_mst_atomic_best_encoder,
 	.atomic_check = intel_dp_mst_atomic_check,
+	.detect_ctx = intel_dp_mst_detect,
 };
 
 static void intel_dp_mst_encoder_destroy(struct drm_encoder *encoder)

drivers/gpu/drm/nouveau/dispnv50/disp.c

@@ -986,20 +986,11 @@ nv50_mstc_atomic_check(struct drm_connector *connector,
 	return drm_dp_atomic_release_vcpi_slots(state, mgr, mstc->port);
 }
 
-static const struct drm_connector_helper_funcs
-nv50_mstc_help = {
-	.get_modes = nv50_mstc_get_modes,
-	.mode_valid = nv50_mstc_mode_valid,
-	.best_encoder = nv50_mstc_best_encoder,
-	.atomic_best_encoder = nv50_mstc_atomic_best_encoder,
-	.atomic_check = nv50_mstc_atomic_check,
-};
-
-static enum drm_connector_status
-nv50_mstc_detect(struct drm_connector *connector, bool force)
+static int
+nv50_mstc_detect(struct drm_connector *connector,
+		 struct drm_modeset_acquire_ctx *ctx, bool force)
 {
 	struct nv50_mstc *mstc = nv50_mstc(connector);
-	enum drm_connector_status conn_status;
 	int ret;
 
 	if (drm_connector_is_unregistered(connector))
@@ -1009,14 +1000,24 @@ nv50_mstc_detect(struct drm_connector *connector, bool force)
 	if (ret < 0 && ret != -EACCES)
 		return connector_status_disconnected;
 
-	conn_status = drm_dp_mst_detect_port(connector, mstc->port->mgr,
-					     mstc->port);
+	ret = drm_dp_mst_detect_port(connector, ctx, mstc->port->mgr,
+				     mstc->port);
 
 	pm_runtime_mark_last_busy(connector->dev->dev);
 	pm_runtime_put_autosuspend(connector->dev->dev);
-	return conn_status;
+	return ret;
 }
 
+static const struct drm_connector_helper_funcs
+nv50_mstc_help = {
+	.get_modes = nv50_mstc_get_modes,
+	.mode_valid = nv50_mstc_mode_valid,
+	.best_encoder = nv50_mstc_best_encoder,
+	.atomic_best_encoder = nv50_mstc_atomic_best_encoder,
+	.atomic_check = nv50_mstc_atomic_check,
+	.detect_ctx = nv50_mstc_detect,
+};
+
 static void
 nv50_mstc_destroy(struct drm_connector *connector)
 {
@@ -1031,7 +1032,6 @@ nv50_mstc_destroy(struct drm_connector *connector)
 static const struct drm_connector_funcs
 nv50_mstc = {
 	.reset = nouveau_conn_reset,
-	.detect = nv50_mstc_detect,
 	.fill_modes = drm_helper_probe_single_connector_modes,
 	.destroy = nv50_mstc_destroy,
 	.atomic_duplicate_state = nouveau_conn_atomic_duplicate_state,
@@ -1309,14 +1309,14 @@ nv50_mstm_fini(struct nv50_mstm *mstm)
 }
 
 static void
-nv50_mstm_init(struct nv50_mstm *mstm)
+nv50_mstm_init(struct nv50_mstm *mstm, bool runtime)
 {
 	int ret;
 
 	if (!mstm || !mstm->mgr.mst_state)
 		return;
 
-	ret = drm_dp_mst_topology_mgr_resume(&mstm->mgr);
+	ret = drm_dp_mst_topology_mgr_resume(&mstm->mgr, !runtime);
 	if (ret == -1) {
 		drm_dp_mst_topology_mgr_set_mst(&mstm->mgr, false);
 		drm_kms_helper_hotplug_event(mstm->mgr.dev);
@@ -2263,7 +2263,7 @@ nv50_display_init(struct drm_device *dev, bool resume, bool runtime)
 		if (encoder->encoder_type != DRM_MODE_ENCODER_DPMST) {
 			struct nouveau_encoder *nv_encoder =
 				nouveau_encoder(encoder);
-			nv50_mstm_init(nv_encoder->dp.mstm);
+			nv50_mstm_init(nv_encoder->dp.mstm, runtime);
 		}
 	}
 

drivers/gpu/drm/nouveau/nouveau_connector.c

@@ -1130,6 +1130,16 @@ nouveau_connector_hotplug(struct nvif_notify *notify)
 	const char *name = connector->name;
 	struct nouveau_encoder *nv_encoder;
 	int ret;
+	bool plugged = (rep->mask != NVIF_NOTIFY_CONN_V0_UNPLUG);
+
+	if (rep->mask & NVIF_NOTIFY_CONN_V0_IRQ) {
+		NV_DEBUG(drm, "service %s\n", name);
+		drm_dp_cec_irq(&nv_connector->aux);
+		if ((nv_encoder = find_encoder(connector, DCB_OUTPUT_DP)))
+			nv50_mstm_service(nv_encoder->dp.mstm);
+
+		return NVIF_NOTIFY_KEEP;
+	}
 
 	ret = pm_runtime_get(drm->dev->dev);
 	if (ret == 0) {
@@ -1150,25 +1160,16 @@ nouveau_connector_hotplug(struct nvif_notify *notify)
 		return NVIF_NOTIFY_DROP;
 	}
 
-	if (rep->mask & NVIF_NOTIFY_CONN_V0_IRQ) {
-		NV_DEBUG(drm, "service %s\n", name);
-		drm_dp_cec_irq(&nv_connector->aux);
-		if ((nv_encoder = find_encoder(connector, DCB_OUTPUT_DP)))
-			nv50_mstm_service(nv_encoder->dp.mstm);
-	} else {
-		bool plugged = (rep->mask != NVIF_NOTIFY_CONN_V0_UNPLUG);
-
+	if (!plugged)
+		drm_dp_cec_unset_edid(&nv_connector->aux);
+	NV_DEBUG(drm, "%splugged %s\n", plugged ? "" : "un", name);
+	if ((nv_encoder = find_encoder(connector, DCB_OUTPUT_DP))) {
 		if (!plugged)
-			drm_dp_cec_unset_edid(&nv_connector->aux);
-		NV_DEBUG(drm, "%splugged %s\n", plugged ? "" : "un", name);
-		if ((nv_encoder = find_encoder(connector, DCB_OUTPUT_DP))) {
-			if (!plugged)
-				nv50_mstm_remove(nv_encoder->dp.mstm);
-		}
-
-		drm_helper_hpd_irq_event(connector->dev);
+			nv50_mstm_remove(nv_encoder->dp.mstm);
 	}
 
+	drm_helper_hpd_irq_event(connector->dev);
+
 	pm_runtime_mark_last_busy(drm->dev->dev);
 	pm_runtime_put_autosuspend(drm->dev->dev);
 	return NVIF_NOTIFY_KEEP;

drivers/gpu/drm/nouveau/nouveau_display.c

@@ -407,6 +407,17 @@ nouveau_display_init(struct drm_device *dev, bool resume, bool runtime)
 	struct drm_connector_list_iter conn_iter;
 	int ret;
 
+	/*
+	 * Enable hotplug interrupts (done as early as possible, since we need
+	 * them for MST)
+	 */
+	drm_connector_list_iter_begin(dev, &conn_iter);
+	nouveau_for_each_non_mst_connector_iter(connector, &conn_iter) {
+		struct nouveau_connector *conn = nouveau_connector(connector);
+		nvif_notify_get(&conn->hpd);
+	}
+	drm_connector_list_iter_end(&conn_iter);
+
 	ret = disp->init(dev, resume, runtime);
 	if (ret)
 		return ret;
@@ -416,14 +427,6 @@ nouveau_display_init(struct drm_device *dev, bool resume, bool runtime)
 	 */
 	drm_kms_helper_poll_enable(dev);
 
-	/* enable hotplug interrupts */
-	drm_connector_list_iter_begin(dev, &conn_iter);
-	nouveau_for_each_non_mst_connector_iter(connector, &conn_iter) {
-		struct nouveau_connector *conn = nouveau_connector(connector);
-		nvif_notify_get(&conn->hpd);
-	}
-	drm_connector_list_iter_end(&conn_iter);
-
 	return ret;
 }
 

drivers/gpu/drm/radeon/radeon_dp_mst.c

@@ -233,21 +233,26 @@ drm_encoder *radeon_mst_best_encoder(struct drm_connector *connector)
 	return &radeon_connector->mst_encoder->base;
 }
 
+static int
+radeon_dp_mst_detect(struct drm_connector *connector,
+		     struct drm_modeset_acquire_ctx *ctx,
+		     bool force)
+{
+	struct radeon_connector *radeon_connector =
+		to_radeon_connector(connector);
+	struct radeon_connector *master = radeon_connector->mst_port;
+
+	return drm_dp_mst_detect_port(connector, ctx, &master->mst_mgr,
+				      radeon_connector->port);
+}
+
 static const struct drm_connector_helper_funcs radeon_dp_mst_connector_helper_funcs = {
 	.get_modes = radeon_dp_mst_get_modes,
 	.mode_valid = radeon_dp_mst_mode_valid,
 	.best_encoder = radeon_mst_best_encoder,
+	.detect_ctx = radeon_dp_mst_detect,
 };
 
-static enum drm_connector_status
-radeon_dp_mst_detect(struct drm_connector *connector, bool force)
-{
-	struct radeon_connector *radeon_connector = to_radeon_connector(connector);
-	struct radeon_connector *master = radeon_connector->mst_port;
-
-	return drm_dp_mst_detect_port(connector, &master->mst_mgr, radeon_connector->port);
-}
-
 static void
 radeon_dp_mst_connector_destroy(struct drm_connector *connector)
 {
@@ -262,7 +267,6 @@ radeon_dp_mst_connector_destroy(struct drm_connector *connector)
 
 static const struct drm_connector_funcs radeon_dp_mst_connector_funcs = {
 	.dpms = drm_helper_connector_dpms,
-	.detect = radeon_dp_mst_detect,
 	.fill_modes = drm_helper_probe_single_connector_modes,
 	.destroy = radeon_dp_mst_connector_destroy,
 };

include/drm/drm_dp_mst_helper.h

@@ -26,6 +26,26 @@
 #include <drm/drm_dp_helper.h>
 #include <drm/drm_atomic.h>
 
+#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
+#include <linux/stackdepot.h>
+#include <linux/timekeeping.h>
+
+enum drm_dp_mst_topology_ref_type {
+	DRM_DP_MST_TOPOLOGY_REF_GET,
+	DRM_DP_MST_TOPOLOGY_REF_PUT,
+};
+
+struct drm_dp_mst_topology_ref_history {
+	struct drm_dp_mst_topology_ref_entry {
+		enum drm_dp_mst_topology_ref_type type;
+		int count;
+		ktime_t ts_nsec;
+		depot_stack_handle_t backtrace;
+	} *entries;
+	int len;
+};
+#endif /* IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) */
+
 struct drm_dp_mst_branch;
 
 /**
@@ -45,21 +65,31 @@ struct drm_dp_vcpi {
 /**
  * struct drm_dp_mst_port - MST port
  * @port_num: port number
- * @input: if this port is an input port.
- * @mcs: message capability status - DP 1.2 spec.
- * @ddps: DisplayPort Device Plug Status - DP 1.2
- * @pdt: Peer Device Type
- * @ldps: Legacy Device Plug Status
- * @dpcd_rev: DPCD revision of device on this port
- * @num_sdp_streams: Number of simultaneous streams
- * @num_sdp_stream_sinks: Number of stream sinks
- * @available_pbn: Available bandwidth for this port.
+ * @input: if this port is an input port. Protected by
+ * &drm_dp_mst_topology_mgr.base.lock.
+ * @mcs: message capability status - DP 1.2 spec. Protected by
+ * &drm_dp_mst_topology_mgr.base.lock.
+ * @ddps: DisplayPort Device Plug Status - DP 1.2. Protected by
+ * &drm_dp_mst_topology_mgr.base.lock.
+ * @pdt: Peer Device Type. Protected by
+ * &drm_dp_mst_topology_mgr.base.lock.
+ * @ldps: Legacy Device Plug Status. Protected by
+ * &drm_dp_mst_topology_mgr.base.lock.
+ * @dpcd_rev: DPCD revision of device on this port. Protected by
+ * &drm_dp_mst_topology_mgr.base.lock.
+ * @num_sdp_streams: Number of simultaneous streams. Protected by
+ * &drm_dp_mst_topology_mgr.base.lock.
+ * @num_sdp_stream_sinks: Number of stream sinks. Protected by
+ * &drm_dp_mst_topology_mgr.base.lock.
+ * @available_pbn: Available bandwidth for this port. Protected by
+ * &drm_dp_mst_topology_mgr.base.lock.
  * @next: link to next port on this branch device
- * @mstb: branch device attach below this port
- * @aux: i2c aux transport to talk to device connected to this port.
+ * @aux: i2c aux transport to talk to device connected to this port, protected
+ * by &drm_dp_mst_topology_mgr.base.lock.
  * @parent: branch device parent of this port
  * @vcpi: Virtual Channel Payload info for this port.
- * @connector: DRM connector this port is connected to.
+ * @connector: DRM connector this port is connected to. Protected by
+ * &drm_dp_mst_topology_mgr.base.lock.
  * @mgr: topology manager this port lives under.
  *
  * This structure represents an MST port endpoint on a device somewhere
@@ -79,6 +109,14 @@ struct drm_dp_mst_port {
 	 */
 	struct kref malloc_kref;
 
+#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
+	/**
+	 * @topology_ref_history: A history of each topology
+	 * reference/dereference. See CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS.
+	 */
+	struct drm_dp_mst_topology_ref_history topology_ref_history;
+#endif
+
 	u8 port_num;
 	bool input;
 	bool mcs;
@@ -90,7 +128,17 @@ struct drm_dp_mst_port {
 	u8 num_sdp_stream_sinks;
 	uint16_t available_pbn;
 	struct list_head next;
-	struct drm_dp_mst_branch *mstb; /* pointer to an mstb if this port has one */
+	/**
+	 * @mstb: the branch device connected to this port, if there is one.
+	 * This should be considered protected for reading by
+	 * &drm_dp_mst_topology_mgr.lock. There are two exceptions to this:
+	 * &drm_dp_mst_topology_mgr.up_req_work and
+	 * &drm_dp_mst_topology_mgr.work, which do not grab
+	 * &drm_dp_mst_topology_mgr.lock during reads but are the only
+	 * updaters of this list and are protected from writing concurrently
+	 * by &drm_dp_mst_topology_mgr.probe_lock.
+	 */
+	struct drm_dp_mst_branch *mstb;
 	struct drm_dp_aux aux; /* i2c bus for this port? */
 	struct drm_dp_mst_branch *parent;
 
@@ -116,7 +164,6 @@ struct drm_dp_mst_port {
  * @lct: Link count total to talk to this branch device.
  * @num_ports: number of ports on the branch.
  * @msg_slots: one bit per transmitted msg slot.
- * @ports: linked list of ports on this branch.
  * @port_parent: pointer to the port parent, NULL if toplevel.
  * @mgr: topology manager for this branch device.
  * @tx_slots: transmission slots for this device.
@@ -143,11 +190,35 @@ struct drm_dp_mst_branch {
 	 */
 	struct kref malloc_kref;
 
+#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
+	/**
+	 * @topology_ref_history: A history of each topology
+	 * reference/dereference. See CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS.
+	 */
+	struct drm_dp_mst_topology_ref_history topology_ref_history;
+#endif
+
+	/**
+	 * @destroy_next: linked-list entry used by
+	 * drm_dp_delayed_destroy_work()
+	 */
+	struct list_head destroy_next;
+
 	u8 rad[8];
 	u8 lct;
 	int num_ports;
 
 	int msg_slots;
+	/**
+	 * @ports: the list of ports on this branch device. This should be
+	 * considered protected for reading by &drm_dp_mst_topology_mgr.lock.
+	 * There are two exceptions to this:
+	 * &drm_dp_mst_topology_mgr.up_req_work and
+	 * &drm_dp_mst_topology_mgr.work, which do not grab
+	 * &drm_dp_mst_topology_mgr.lock during reads but are the only
+	 * updaters of this list and are protected from updating the list
+	 * concurrently by @drm_dp_mst_topology_mgr.probe_lock
+	 */
 	struct list_head ports;
 
 	/* list of tx ops queue for this port */
@@ -494,6 +565,13 @@ struct drm_dp_mst_topology_mgr {
 	 */
 	struct mutex lock;
 
+	/**
+	 * @probe_lock: Prevents @work and @up_req_work, the only writers of
+	 * &drm_dp_mst_port.mstb and &drm_dp_mst_branch.ports, from racing
+	 * while they update the topology.
+	 */
+	struct mutex probe_lock;
+
 	/**
 	 * @mst_state: If this manager is enabled for an MST capable port. False
 	 * if no MST sink/branch devices is connected.
@@ -571,18 +649,49 @@ struct drm_dp_mst_topology_mgr {
 	struct work_struct tx_work;
 
 	/**
-	 * @destroy_connector_list: List of to be destroyed connectors.
+	 * @destroy_port_list: List of to be destroyed connectors.
+	 */
+	struct list_head destroy_port_list;
+	/**
+	 * @destroy_branch_device_list: List of to be destroyed branch
+	 * devices.
+	 */
+	struct list_head destroy_branch_device_list;
+	/**
+	 * @delayed_destroy_lock: Protects @destroy_port_list and
+	 * @destroy_branch_device_list.
+	 */
+	struct mutex delayed_destroy_lock;
+	/**
+	 * @delayed_destroy_work: Work item to destroy MST port and branch
+	 * devices, needed to avoid locking inversion.
+	 */
+	struct work_struct delayed_destroy_work;
+
+	/**
+	 * @up_req_list: List of pending up requests from the topology that
+	 * need to be processed, in chronological order.
 	 */
-	struct list_head destroy_connector_list;
+	struct list_head up_req_list;
 	/**
-	 * @destroy_connector_lock: Protects @connector_list.
+	 * @up_req_lock: Protects @up_req_list
 	 */
-	struct mutex destroy_connector_lock;
+	struct mutex up_req_lock;
 	/**
-	 * @destroy_connector_work: Work item to destroy connectors. Needed to
-	 * avoid locking inversion.
+	 * @up_req_work: Work item to process up requests received from the
+	 * topology. Needed to avoid blocking hotplug handling and sideband
+	 * transmissions.
 	 */
-	struct work_struct destroy_connector_work;
+	struct work_struct up_req_work;
+
+#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
+	/**
+	 * @topology_ref_history_lock: protects
+	 * &drm_dp_mst_port.topology_ref_history and
+	 * &drm_dp_mst_branch.topology_ref_history.
+	 */
+	struct mutex topology_ref_history_lock;
+#endif
 };
 
 int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
@@ -599,7 +708,11 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms
 int drm_dp_mst_hpd_irq(struct drm_dp_mst_topology_mgr *mgr, u8 *esi, bool *handled);
 
 
-enum drm_connector_status drm_dp_mst_detect_port(struct drm_connector *connector, struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port);
+int
+drm_dp_mst_detect_port(struct drm_connector *connector,
+		       struct drm_modeset_acquire_ctx *ctx,
+		       struct drm_dp_mst_topology_mgr *mgr,
+		       struct drm_dp_mst_port *port);
 
 bool drm_dp_mst_port_has_audio(struct drm_dp_mst_topology_mgr *mgr,
 					struct drm_dp_mst_port *port);
@@ -638,7 +751,8 @@ 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 __must_check
-drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr);
+drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr,
+			       bool sync);
 
 ssize_t drm_dp_mst_dpcd_read(struct drm_dp_aux *aux,
 			     unsigned int offset, void *buffer, size_t size);