diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 8c3cfac437f4..adb4298570cc 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2614,21 +2614,33 @@ static int drm_dp_init_vcpi(struct drm_dp_mst_topology_mgr *mgr,
 }
 
 /**
- * drm_dp_atomic_find_vcpi_slots() - Find and add vcpi slots to the state
+ * drm_dp_atomic_find_vcpi_slots() - Find and add VCPI slots to the state
  * @state: global atomic state
  * @mgr: MST topology manager for the port
  * @port: port to find vcpi slots for
  * @pbn: bandwidth required for the mode in PBN
  *
+ * Allocates VCPI slots to @port, replacing any previous VCPI allocations it
+ * may have had. Any atomic drivers which support MST must call this function
+ * in their atomic_check() handlers to change the current VCPI allocation for
+ * the new state. After the ->atomic_check() hooks of the driver and all other
+ * mode objects in the state have been called, DRM will check the final VCPI
+ * allocations to ensure that they will fit into the available bandwidth on
+ * the topology.
+ *
+ * See also: drm_dp_atomic_release_vcpi_slots()
+ *
  * RETURNS:
- * Total slots in the atomic state assigned for this port or error
+ * Total slots in the atomic state assigned for this port, or a negative error
+ * code if the port no longer exists
  */
 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)
 {
 	struct drm_dp_mst_topology_state *topology_state;
-	int req_slots;
+	struct drm_dp_vcpi_allocation *pos, *vcpi = NULL;
+	int prev_slots, req_slots, ret;
 
 	topology_state = drm_atomic_get_mst_topology_state(state, mgr);
 	if (IS_ERR(topology_state))
@@ -2637,20 +2649,41 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
 	port = drm_dp_get_validated_port_ref(mgr, port);
 	if (port == NULL)
 		return -EINVAL;
-	req_slots = DIV_ROUND_UP(pbn, mgr->pbn_div);
-	DRM_DEBUG_KMS("vcpi slots req=%d, avail=%d\n",
-			req_slots, topology_state->avail_slots);
 
-	if (req_slots > topology_state->avail_slots) {
-		drm_dp_put_port(port);
-		return -ENOSPC;
+	/* Find the current allocation for this port, if any */
+	list_for_each_entry(pos, &topology_state->vcpis, next) {
+		if (pos->port == port) {
+			vcpi = pos;
+			prev_slots = vcpi->vcpi;
+			break;
+		}
 	}
+	if (!vcpi)
+		prev_slots = 0;
 
-	topology_state->avail_slots -= req_slots;
-	DRM_DEBUG_KMS("vcpi slots avail=%d", topology_state->avail_slots);
+	req_slots = DIV_ROUND_UP(pbn, mgr->pbn_div);
+
+	DRM_DEBUG_KMS("[CONNECTOR:%d:%s] [MST PORT:%p] vcpi %d -> %d\n",
+		      port->connector->base.id, port->connector->name, port,
+		      prev_slots, req_slots);
 
+	/* Add the new allocation to the state */
+	if (!vcpi) {
+		vcpi = kzalloc(sizeof(*vcpi), GFP_KERNEL);
+		if (!vcpi) {
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		vcpi->port = port;
+		list_add(&vcpi->next, &topology_state->vcpis);
+	}
+	vcpi->vcpi = req_slots;
+
+	ret = req_slots;
+out:
 	drm_dp_put_port(port);
-	return req_slots;
+	return ret;
 }
 EXPORT_SYMBOL(drm_dp_atomic_find_vcpi_slots);
 
@@ -2658,32 +2691,46 @@ EXPORT_SYMBOL(drm_dp_atomic_find_vcpi_slots);
  * drm_dp_atomic_release_vcpi_slots() - Release allocated vcpi slots
  * @state: global atomic state
  * @mgr: MST topology manager for the port
- * @slots: number of vcpi slots to release
+ *
+ * Releases any VCPI slots that have been allocated to a port in the atomic
+ * state. Any atomic drivers which support MST must call this function in
+ * their connector's atomic_check() handler when the connector will no longer
+ * have VCPI allocated (e.g. because it's CRTC was removed).
+ *
+ * It is OK to call this even if @port has been removed from the system, in
+ * which case it will just amount to a no-op.
+ *
+ * See also: drm_dp_atomic_find_vcpi_slots()
  *
  * RETURNS:
- * 0 if @slots were added back to &drm_dp_mst_topology_state->avail_slots or
- * negative error code
+ * 0 if all slots for this port were added back to
+ * &drm_dp_mst_topology_state->avail_slots or negative error code
  */
 int drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,
 				     struct drm_dp_mst_topology_mgr *mgr,
-				     int slots)
+				     struct drm_dp_mst_port *port)
 {
 	struct drm_dp_mst_topology_state *topology_state;
+	struct drm_dp_vcpi_allocation *tmp, *pos;
 
 	topology_state = drm_atomic_get_mst_topology_state(state, mgr);
 	if (IS_ERR(topology_state))
 		return PTR_ERR(topology_state);
 
-	/* We cannot rely on port->vcpi.num_slots to update
-	 * topology_state->avail_slots as the port may not exist if the parent
-	 * branch device was unplugged. This should be fixed by tracking
-	 * per-port slot allocation in drm_dp_mst_topology_state instead of
-	 * depending on the caller to tell us how many slots to release.
-	 */
-	topology_state->avail_slots += slots;
-	DRM_DEBUG_KMS("vcpi slots released=%d, avail=%d\n",
-			slots, topology_state->avail_slots);
+	list_for_each_entry_safe(pos, tmp, &topology_state->vcpis, next) {
+		if (pos->port == port) {
+			list_del(&pos->next);
+			DRM_DEBUG_KMS("[MST PORT:%p] vcpi %d -> 0\n",
+				      port, pos->vcpi);
 
+			kfree(pos);
+			return 0;
+		}
+	}
+
+	/* If no allocation was found, all that means is that the port was
+	 * destroyed since the last atomic commit. That's OK!
+	 */
 	return 0;
 }
 EXPORT_SYMBOL(drm_dp_atomic_release_vcpi_slots);
@@ -3112,15 +3159,50 @@ static void drm_dp_destroy_connector_work(struct work_struct *work)
 static struct drm_private_state *
 drm_dp_mst_duplicate_state(struct drm_private_obj *obj)
 {
-	struct drm_dp_mst_topology_state *state;
+	struct drm_dp_mst_topology_state *state, *old_state =
+		to_dp_mst_topology_state(obj->state);
+	struct drm_dp_mst_topology_mgr *mgr = old_state->mgr;
+	struct drm_dp_mst_port *port;
+	struct drm_dp_vcpi_allocation *pos, *vcpi;
 
-	state = kmemdup(obj->state, sizeof(*state), GFP_KERNEL);
+	state = kzalloc(sizeof(*state), GFP_KERNEL);
 	if (!state)
 		return NULL;
 
 	__drm_atomic_helper_private_obj_duplicate_state(obj, &state->base);
 
+	state->mgr = mgr;
+	INIT_LIST_HEAD(&state->vcpis);
+
+	/* Copy over the VCPI allocations for ports that still exist */
+	list_for_each_entry(pos, &old_state->vcpis, next) {
+		port = drm_dp_get_validated_port_ref(mgr, pos->port);
+		if (!port) {
+			DRM_DEBUG_ATOMIC("[MST PORT:%p] is gone, vcpi %d -> 0\n",
+					 pos->port, pos->vcpi);
+			continue;
+		}
+
+		vcpi = kzalloc(sizeof(*vcpi), GFP_KERNEL);
+		if (!vcpi) {
+			drm_dp_put_port(port);
+			goto fail_alloc;
+		}
+
+		vcpi->port = port;
+		vcpi->vcpi = pos->vcpi;
+		list_add(&vcpi->next, &state->vcpis);
+		drm_dp_put_port(port);
+	}
+
 	return &state->base;
+
+fail_alloc:
+	list_for_each_entry_safe(pos, vcpi, &state->vcpis, next)
+		kfree(pos);
+	kfree(state);
+
+	return NULL;
 }
 
 static void drm_dp_mst_destroy_state(struct drm_private_obj *obj,
@@ -3128,13 +3210,45 @@ static void drm_dp_mst_destroy_state(struct drm_private_obj *obj,
 {
 	struct drm_dp_mst_topology_state *mst_state =
 		to_dp_mst_topology_state(state);
+	struct drm_dp_vcpi_allocation *pos, *tmp;
+
+	list_for_each_entry_safe(pos, tmp, &mst_state->vcpis, next)
+		kfree(pos);
 
 	kfree(mst_state);
 }
 
+static int drm_dp_mst_atomic_check(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 drm_dp_mst_topology_mgr *mgr = mst_state->mgr;
+	struct drm_dp_vcpi_allocation *pos;
+	int avail_slots = 63;
+
+	list_for_each_entry(pos, &mst_state->vcpis, next) {
+		DRM_DEBUG_ATOMIC("[MST PORT:%p] requires %d vcpi slots\n",
+				 pos->port, pos->vcpi);
+
+		avail_slots -= pos->vcpi;
+		if (avail_slots < 0) {
+			DRM_DEBUG_ATOMIC("[MST PORT:%p] not enough vcpi slots in state %p (avail=%d)\n",
+					 pos->port, state,
+					 avail_slots + pos->vcpi);
+			return -ENOSPC;
+		}
+	}
+	DRM_DEBUG_ATOMIC("[MST MGR:%p] state %p vcpi avail=%d used=%d\n",
+			 mgr, state, avail_slots, 63 - avail_slots);
+
+	return 0;
+}
+
 static const struct drm_private_state_funcs mst_state_funcs = {
 	.atomic_duplicate_state = drm_dp_mst_duplicate_state,
 	.atomic_destroy_state = drm_dp_mst_destroy_state,
+	.atomic_check = drm_dp_mst_atomic_check,
 };
 
 /**
@@ -3213,9 +3327,7 @@ int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
 		return -ENOMEM;
 
 	mst_state->mgr = mgr;
-
-	/* max. time slots - one slot for MTP header */
-	mst_state->avail_slots = 63;
+	INIT_LIST_HEAD(&mst_state->vcpis);
 
 	drm_atomic_private_obj_init(&mgr->base,
 				    &mst_state->base,
diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
index 8b71d64ebd9d..aaf904738b78 100644
--- a/drivers/gpu/drm/i915/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/intel_dp_mst.c
@@ -114,28 +114,31 @@ static int intel_dp_mst_atomic_check(struct drm_connector *connector,
 	struct drm_connector_state *old_conn_state;
 	struct drm_crtc *old_crtc;
 	struct drm_crtc_state *crtc_state;
-	int slots, ret = 0;
+	struct intel_connector *intel_connector =
+		to_intel_connector(connector);
+	struct drm_dp_mst_topology_mgr *mgr =
+		&intel_connector->mst_port->mst_mgr;
+	struct drm_dp_mst_port *port = intel_connector->port;
+	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;
+	/* Free VCPI, since compute_config() won't be run */
+	if (!new_conn_state->crtc) {
+		crtc_state = drm_atomic_get_new_crtc_state(state, old_crtc);
 
-		old_encoder = old_conn_state->best_encoder;
-		mgr = &enc_to_mst(old_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
-			to_intel_crtc_state(crtc_state)->dp_m_n.tu = 0;
+		ret = drm_dp_atomic_release_vcpi_slots(state, mgr, port);
+		if (ret) {
+			DRM_DEBUG_KMS("failed releasing vcpi slots: %d\n",
+				      ret);
+			return ret;
+		}
+		to_intel_crtc_state(crtc_state)->dp_m_n.tu = 0;
 	}
+
 	return ret;
 }
 
diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
index 59f005b419cf..4c0805e56335 100644
--- a/include/drm/drm_dp_mst_helper.h
+++ b/include/drm/drm_dp_mst_helper.h
@@ -406,9 +406,15 @@ struct drm_dp_payload {
 
 #define to_dp_mst_topology_state(x) container_of(x, struct drm_dp_mst_topology_state, base)
 
+struct drm_dp_vcpi_allocation {
+	struct drm_dp_mst_port *port;
+	int vcpi;
+	struct list_head next;
+};
+
 struct drm_dp_mst_topology_state {
 	struct drm_private_state base;
-	int avail_slots;
+	struct list_head vcpis;
 	struct drm_dp_mst_topology_mgr *mgr;
 };
 
@@ -624,7 +630,7 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
 				  struct drm_dp_mst_port *port, int pbn);
 int drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,
 				     struct drm_dp_mst_topology_mgr *mgr,
-				     int slots);
+				     struct drm_dp_mst_port *port);
 int drm_dp_send_power_updown_phy(struct drm_dp_mst_topology_mgr *mgr,
 				 struct drm_dp_mst_port *port, bool power_up);
 
