Bluetooth: audio: ascs: Fix ASE state transition due to CIS link loss

This fixes ASE state transition to QoS Configured state that shall be
done autononously when CIS has been terminated due to link loss.

As per ASCS v1.0:
"If the server detects link loss of a CIS for an ASE in the Streaming
state or the Disabling state, the server shall immediately transition
that ASE to the QoS Configured state. Link loss of a CIS for an ASE in
any state other than Streaming or Disabling shall not cause a
transition of the ASE state machine."

Fixes: #60669
Signed-off-by: Mariusz Skamra <[email protected]>

Author: MariuszSkamra

subsys/bluetooth/audio/ascs.c

@@ -63,6 +63,7 @@ static struct bt_ascs_ase {
 	struct k_work_delayable disconnect_work;
 	struct k_work state_transition_work;
 	enum bt_bap_ep_state state_pending;
+	bool unexpected_iso_link_loss;
 } ase_pool[CONFIG_BT_ASCS_MAX_ACTIVE_ASES];
 
 #define MAX_CODEC_CONFIG                                                                           \
@@ -354,6 +355,10 @@ static void ase_set_state_disabling(struct bt_ascs_ase *ase)
 	if (ops != NULL && ops->disabled != NULL) {
 		ops->disabled(stream);
 	}
+
+	if (ase->unexpected_iso_link_loss) {
+		ascs_ep_set_state(&ase->ep, BT_BAP_EP_STATE_QOS_CONFIGURED);
+	}
 }
 
 static void ase_set_state_releasing(struct bt_ascs_ase *ase)
@@ -399,9 +404,6 @@ static void state_transition_work_handler(struct k_work *work)
 		if (reason == BT_HCI_ERR_SUCCESS) {
 			/* Default to BT_HCI_ERR_UNSPECIFIED if no other reason is set */
 			reason = BT_HCI_ERR_UNSPECIFIED;
-		} else {
-			/* Reset reason */
-			ep->reason = BT_HCI_ERR_SUCCESS;
 		}
 
 		if (ops != NULL && ops->stopped != NULL) {
@@ -823,6 +825,7 @@ static void ascs_update_sdu_size(struct bt_bap_ep *ep)
 
 static void ascs_ep_iso_connected(struct bt_bap_ep *ep)
 {
+	struct bt_ascs_ase *ase = CONTAINER_OF(ep, struct bt_ascs_ase, ep);
 	struct bt_bap_stream *stream;
 
 	if (ep->status.state != BT_BAP_EP_STATE_ENABLING) {
@@ -837,6 +840,10 @@ static void ascs_ep_iso_connected(struct bt_bap_ep *ep)
 		return;
 	}
 
+	/* Reset reason */
+	ep->reason = BT_HCI_ERR_SUCCESS;
+	ase->unexpected_iso_link_loss = false;
+
 	/* Some values are not provided by the HCI events when the CIS is established for the
 	 * peripheral, so we update them here based on the parameters provided by the BAP Unicast
 	 * Client
@@ -897,18 +904,23 @@ static void ascs_ep_iso_disconnected(struct bt_bap_ep *ep, uint8_t reason)
 
 	if (ep->status.state == BT_BAP_EP_STATE_RELEASING) {
 		ascs_ep_set_state(ep, BT_BAP_EP_STATE_IDLE);
-	} else {
+	} else if (ep->status.state == BT_BAP_EP_STATE_STREAMING) {
+		/* CIS has been unexpectedly disconnected */
+		ase->unexpected_iso_link_loss = true;
+
 		/* The ASE state machine goes into different states from this operation
 		 * based on whether it is a source or a sink ASE.
 		 */
-		if (ep->status.state == BT_BAP_EP_STATE_STREAMING ||
-		    ep->status.state == BT_BAP_EP_STATE_ENABLING) {
-			if (ep->dir == BT_AUDIO_DIR_SOURCE) {
-				ascs_ep_set_state(ep, BT_BAP_EP_STATE_DISABLING);
-			} else {
-				ascs_ep_set_state(ep, BT_BAP_EP_STATE_QOS_CONFIGURED);
-			}
+		if (ep->dir == BT_AUDIO_DIR_SOURCE) {
+			ascs_ep_set_state(ep, BT_BAP_EP_STATE_DISABLING);
+		} else {
+			ascs_ep_set_state(ep, BT_BAP_EP_STATE_QOS_CONFIGURED);
 		}
+	} else if (ep->status.state == BT_BAP_EP_STATE_DISABLING) {
+		/* CIS has been unexpectedly disconnected */
+		ase->unexpected_iso_link_loss = true;
+
+		ascs_ep_set_state(ep, BT_BAP_EP_STATE_QOS_CONFIGURED);
 	}
 }