Bluetooth: Audio: Only allow receiver to send start command

Only the receiver of the audio is allowed to send the
receiver start ready command.

Furthermore, this removes the automated transition to the
streaming state on the server, as the server now shall
call bt_audio_stream_start to put the stream into the
streaming state.

Signed-off-by: Emil Gydesen <[email protected]>

Author: Thalley

include/zephyr/bluetooth/audio/audio.h

@@ -1937,6 +1937,17 @@ int bt_audio_stream_disable(struct bt_audio_stream *stream);
  *  This procedure is used by a unicast client or unicast server to make a
  *  stream start streaming.
  *
+ *  For the unicast client, this will connect the CIS for the stream before
+ *  sending the start command.
+ *
+ *  For the unicast server, this will put a @ref BT_AUDIO_DIR_SINK stream into
+ *  the streaming state if the CIS is connected (initialized by the unicast
+ *  client). If the CIS is not connected yet, the stream will go into the
+ *  streaming state as soon as the CIS is connected.
+ *  @ref BT_AUDIO_DIR_SOURCE streams will go into the streaming state when the
+ *  unicast client sends the Receiver Start Ready operation, which will trigger
+ *  the @ref bt_audio_unicast_server_cb.start() callback.
+ *
  *  This shall only be called for unicast streams.
  *  Broadcast sinks will always be started once synchronized, and broadcast
  *  source streams shall be started with bt_audio_broadcast_source_start().

samples/bluetooth/unicast_audio_server/src/main.c

@@ -38,9 +38,9 @@ static struct bt_codec lc3_codec =
 
 static struct bt_conn *default_conn;
 static struct k_work_delayable audio_send_work;
-static struct bt_audio_stream streams[CONFIG_BT_ASCS_ASE_SNK_COUNT + CONFIG_BT_ASCS_ASE_SRC_COUNT];
+static struct bt_audio_stream sink_streams[CONFIG_BT_ASCS_ASE_SNK_COUNT];
 static struct bt_audio_source {
-	struct bt_audio_stream *stream;
+	struct bt_audio_stream stream;
 	uint16_t seq_num;
 	uint16_t max_sdu;
 	size_t len_to_send;
@@ -72,7 +72,7 @@ static const struct bt_data ad[] = {
 static uint16_t get_and_incr_seq_num(const struct bt_audio_stream *stream)
 {
 	for (size_t i = 0U; i < configured_source_stream_count; i++) {
-		if (stream == source_streams[i].stream) {
+		if (stream == &source_streams[i].stream) {
 			return source_streams[i].seq_num++;
 		}
 	}
@@ -190,7 +190,7 @@ static void audio_timer_timeout(struct k_work *work)
 	 * data going to the server)
 	 */
 	for (size_t i = 0; i < configured_source_stream_count; i++) {
-		struct bt_audio_stream *stream = source_streams[i].stream;
+		struct bt_audio_stream *stream = &source_streams[i].stream;
 
 		buf = net_buf_alloc(&tx_pool, K_FOREVER);
 		net_buf_reserve(buf, BT_ISO_CHAN_SEND_RESERVE);
@@ -217,13 +217,41 @@ static void audio_timer_timeout(struct k_work *work)
 	k_work_schedule(&audio_send_work, K_MSEC(1000U));
 }
 
-static struct bt_audio_stream *stream_alloc(void)
+static enum bt_audio_dir stream_dir(const struct bt_audio_stream *stream)
 {
-	for (size_t i = 0; i < ARRAY_SIZE(streams); i++) {
-		struct bt_audio_stream *stream = &streams[i];
+	for (size_t i = 0U; i < ARRAY_SIZE(source_streams); i++) {
+		if (stream == &source_streams[i].stream) {
+			return BT_AUDIO_DIR_SOURCE;
+		}
+	}
 
-		if (!stream->conn) {
-			return stream;
+	for (size_t i = 0U; i < ARRAY_SIZE(sink_streams); i++) {
+		if (stream == &sink_streams[i]) {
+			return BT_AUDIO_DIR_SINK;
+		}
+	}
+
+	__ASSERT(false, "Invalid stream %p", stream);
+	return 0;
+}
+
+static struct bt_audio_stream *stream_alloc(enum bt_audio_dir dir)
+{
+	if (dir == BT_AUDIO_DIR_SOURCE) {
+		for (size_t i = 0; i < ARRAY_SIZE(source_streams); i++) {
+			struct bt_audio_stream *stream = &source_streams[i].stream;
+
+			if (!stream->conn) {
+				return stream;
+			}
+		}
+	} else {
+		for (size_t i = 0; i < ARRAY_SIZE(sink_streams); i++) {
+			struct bt_audio_stream *stream = &sink_streams[i];
+
+			if (!stream->conn) {
+				return stream;
+			}
 		}
 	}
 
@@ -238,7 +266,7 @@ static int lc3_config(struct bt_conn *conn, const struct bt_audio_ep *ep, enum b
 
 	print_codec(codec);
 
-	*stream = stream_alloc();
+	*stream = stream_alloc(dir);
 	if (*stream == NULL) {
 		printk("No streams available\n");
 
@@ -248,7 +276,7 @@ static int lc3_config(struct bt_conn *conn, const struct bt_audio_ep *ep, enum b
 	printk("ASE Codec Config stream %p\n", *stream);
 
 	if (dir == BT_AUDIO_DIR_SOURCE) {
-		source_streams[configured_source_stream_count++].stream = *stream;
+		configured_source_stream_count++;
 	}
 
 	*pref = qos_pref;
@@ -284,7 +312,7 @@ static int lc3_qos(struct bt_audio_stream *stream, const struct bt_codec_qos *qo
 	print_qos(qos);
 
 	for (size_t i = 0U; i < configured_source_stream_count; i++) {
-		if (source_streams[i].stream == stream) {
+		if (stream == &source_streams[i].stream) {
 			source_streams[i].max_sdu = qos->sdu;
 			break;
 		}
@@ -335,8 +363,9 @@ static int lc3_start(struct bt_audio_stream *stream)
 	printk("Start: stream %p\n", stream);
 
 	for (size_t i = 0U; i < configured_source_stream_count; i++) {
-		if (source_streams[i].stream == stream) {
+		if (stream == &source_streams[i].stream) {
 			source_streams[i].seq_num = 0U;
+			source_streams[i].len_to_send = 0U;
 			break;
 		}
 	}
@@ -514,13 +543,29 @@ static void stream_stopped(struct bt_audio_stream *stream)
 	k_work_cancel_delayable(&audio_send_work);
 }
 
+
+static void stream_enabled_cb(struct bt_audio_stream *stream)
+{
+	/* The unicast server is responsible for starting sink ASEs after the
+	 * client has enabled them.
+	 */
+	if (stream_dir(stream) == BT_AUDIO_DIR_SINK) {
+		const int err = bt_audio_stream_start(stream);
+
+		if (err != 0) {
+			printk("Failed to start stream %p: %d", stream, err);
+		}
+	}
+}
+
 static struct bt_audio_stream_ops stream_ops = {
 #if defined(CONFIG_LIBLC3)
 	.recv = stream_recv_lc3_codec,
 #else
 	.recv = stream_recv,
 #endif
 	.stopped = stream_stopped,
+	.enabled = stream_enabled_cb,
 };
 
 static void connected(struct bt_conn *conn, uint8_t err)
@@ -674,8 +719,13 @@ void main(void)
 	bt_pacs_cap_register(BT_AUDIO_DIR_SINK, &cap_sink);
 	bt_pacs_cap_register(BT_AUDIO_DIR_SOURCE, &cap_source);
 
-	for (size_t i = 0; i < ARRAY_SIZE(streams); i++) {
-		bt_audio_stream_cb_register(&streams[i], &stream_ops);
+	for (size_t i = 0; i < ARRAY_SIZE(sink_streams); i++) {
+		bt_audio_stream_cb_register(&sink_streams[i], &stream_ops);
+	}
+
+	for (size_t i = 0; i < ARRAY_SIZE(source_streams); i++) {
+		bt_audio_stream_cb_register(&source_streams[i].stream,
+					    &stream_ops);
 	}
 
 	err = set_location();
@@ -726,7 +776,6 @@ void main(void)
 		}
 
 		/* reset data */
-		(void)memset(source_streams, 0, sizeof(source_streams));
 		configured_source_stream_count = 0U;
 		k_work_cancel_delayable_sync(&audio_send_work, &sync);
 

subsys/bluetooth/audio/ascs.c

@@ -567,50 +567,28 @@ static void ascs_iso_sent(struct bt_iso_chan *chan)
 	}
 }
 
-static int ase_stream_start(struct bt_audio_stream *stream)
-{
-	int err = 0;
-
-	if (unicast_server_cb != NULL && unicast_server_cb->start != NULL) {
-		err = unicast_server_cb->start(stream);
-	} else {
-		err = -ENOTSUP;
-	}
-
-	ascs_ep_set_state(stream->ep, BT_AUDIO_EP_STATE_STREAMING);
-
-	return err;
-}
-
 static void ascs_ep_iso_connected(struct bt_audio_ep *ep)
 {
 	struct bt_audio_stream *stream;
-	int err;
 
 	if (ep->status.state != BT_AUDIO_EP_STATE_ENABLING) {
 		LOG_DBG("ep %p not in enabling state: %s",
 		       ep, bt_audio_ep_state_str(ep->status.state));
 		return;
 	}
 
-	if (ep->dir == BT_AUDIO_DIR_SOURCE && !ep->receiver_ready) {
-		return;
-	} else if (ep->dir == BT_AUDIO_DIR_SINK) {
-		/* SINK ASEs can autonomously go into the streaming state if
-		 * the CIS is connected
-		 */
-		ascs_ep_set_state(ep, BT_AUDIO_EP_STATE_STREAMING);
-	}
-
 	stream = ep->stream;
 	if (stream == NULL) {
 		LOG_ERR("No stream for ep %p", ep);
 		return;
 	}
 
-	err = ase_stream_start(stream);
-	if (err) {
-		LOG_ERR("Could not start stream %d", err);
+	if (ep->dir == BT_AUDIO_DIR_SINK && ep->receiver_ready) {
+		/* Source ASEs shall be ISO connected first, and then receive
+		 * the receiver start ready command to enter the streaming
+		 * state
+		 */
+		ascs_ep_set_state(ep, BT_AUDIO_EP_STATE_STREAMING);
 	}
 }
 
@@ -2000,6 +1978,7 @@ static ssize_t ascs_enable(struct bt_ascs *ascs, struct net_buf_simple *buf)
 static void ase_start(struct bt_ascs_ase *ase)
 {
 	struct bt_audio_ep *ep;
+	int err;
 
 	LOG_DBG("ase %p", ase);
 
@@ -2024,22 +2003,36 @@ static void ase_start(struct bt_ascs_ase *ase)
 		ascs_cp_rsp_add(ASE_ID(ase), BT_ASCS_START_OP,
 				BT_ASCS_RSP_INVALID_DIR, BT_ASCS_REASON_NONE);
 		return;
+	} else if (ep->iso->chan.state != BT_ISO_STATE_CONNECTED) {
+		/* An ASE may not go into the streaming state unless the CIS
+		 * is connected
+		 */
+		LOG_WRN("Start failed: CIS not connected: %u",
+			ep->iso->chan.state);
+		ascs_cp_rsp_add(ASE_ID(ase), BT_ASCS_START_OP,
+				BT_ASCS_RSP_INVALID_ASE_STATE,
+				BT_ASCS_REASON_NONE);
+		return;
 	}
 
-	ep->receiver_ready = true;
+	if (unicast_server_cb != NULL && unicast_server_cb->start != NULL) {
+		err = unicast_server_cb->start(ep->stream);
+	} else {
+		err = -ENOTSUP;
+	}
 
-	if (ep->iso->chan.state == BT_ISO_STATE_CONNECTED) {
-		int err;
+	if (err) {
+		LOG_ERR("Start failed: %d", err);
+		ascs_cp_rsp_add(ASE_ID(ase), BT_ASCS_START_OP, err,
+				BT_ASCS_REASON_NONE);
 
-		err = ase_stream_start(ep->stream);
-		if (err) {
-			LOG_ERR("Start failed: %d", err);
-			ascs_cp_rsp_add(ASE_ID(ase), BT_ASCS_START_OP, err,
-					BT_ASCS_REASON_NONE);
-			return;
-		}
+		return;
 	}
 
+	ep->receiver_ready = true;
+
+	ascs_ep_set_state(ep, BT_AUDIO_EP_STATE_STREAMING);
+
 	ascs_cp_rsp_success(ASE_ID(ase), BT_ASCS_START_OP);
 }
 

subsys/bluetooth/audio/endpoint.h

@@ -44,7 +44,7 @@ struct bt_audio_ep {
 	struct bt_codec_qos_pref qos_pref;
 	struct bt_audio_iso *iso;
 
-	/* FIXME: Replace with metastate */
+	/* Used by the unicast server */
 	bool receiver_ready;
 
 	/* TODO: Create a union to reduce memory usage */

subsys/bluetooth/audio/unicast_server.c

@@ -10,6 +10,7 @@
 
 #include <zephyr/bluetooth/audio/audio.h>
 
+#include "audio_iso.h"
 #include "pacs_internal.h"
 #include "endpoint.h"
 
@@ -82,19 +83,23 @@ int bt_unicast_server_reconfig(struct bt_audio_stream *stream,
 
 int bt_unicast_server_start(struct bt_audio_stream *stream)
 {
-	int err;
+	struct bt_audio_ep *ep = stream->ep;
 
-	if (unicast_server_cb != NULL && unicast_server_cb->start != NULL) {
-		err = unicast_server_cb->start(stream);
-	} else {
-		err = -ENOTSUP;
-	}
+	if (ep->dir != BT_AUDIO_DIR_SINK) {
+		LOG_DBG("Invalid operation for stream %p with dir %u",
+			stream, ep->dir);
 
-	if (err != 0) {
-		return err;
+		return -EINVAL;
 	}
 
-	ascs_ep_set_state(stream->ep, BT_AUDIO_EP_STATE_STREAMING);
+	/* If ISO is connected to go streaming state,
+	 * else wait for ISO to be connected
+	 */
+	if (ep->iso->chan.state == BT_ISO_STATE_CONNECTED) {
+		ascs_ep_set_state(ep, BT_AUDIO_EP_STATE_STREAMING);
+	} else {
+		ep->receiver_ready = true;
+	}
 
 	return 0;
 }