node: use new node.transport property to start/stop transport

Instead of modifying the driver activation to start/stop the transport,
use a property on the node and let the server handle the change.

pipewire-jack/src/pipewire-jack.c

@@ -6798,12 +6798,24 @@ int  jack_transport_reposition (jack_client_t *client,
 	return 0;
 }
 
-static void update_command(struct client *c, uint32_t command)
+static int transport_update(struct client* c, int active)
 {
-	struct pw_node_activation *a = c->rt.driver_activation;
-	if (!a)
-		return;
-	SPA_ATOMIC_STORE(a->command, command);
+	pw_log_info("%p: transport %d", c, active);
+
+	pw_thread_loop_lock(c->context.loop);
+	pw_properties_set(c->props, PW_KEY_NODE_TRANSPORT,
+			active ? "true" : "false");
+
+	c->info.change_mask |= SPA_NODE_CHANGE_MASK_PROPS;
+	c->info.props = &c->props->dict;
+
+	pw_client_node_update(c->node,
+                                    PW_CLIENT_NODE_UPDATE_INFO,
+				    0, NULL, &c->info);
+	c->info.change_mask = 0;
+	pw_thread_loop_unlock(c->context.loop);
+
+	return 0;
 }
 
 SPA_EXPORT
@@ -6811,7 +6823,7 @@ void jack_transport_start (jack_client_t *client)
 {
 	struct client *c = (struct client *) client;
 	return_if_fail(c != NULL);
-	update_command(c, PW_NODE_ACTIVATION_COMMAND_START);
+	transport_update(c, true);
 }
 
 SPA_EXPORT
@@ -6819,7 +6831,7 @@ void jack_transport_stop (jack_client_t *client)
 {
 	struct client *c = (struct client *) client;
 	return_if_fail(c != NULL);
-	update_command(c, PW_NODE_ACTIVATION_COMMAND_STOP);
+	transport_update(c, false);
 }
 
 SPA_EXPORT

src/pipewire/context.c

@@ -1221,7 +1221,7 @@ int pw_context_recalc_graph(struct pw_context *context, const char *reason)
 	const uint32_t *rates;
 	uint32_t max_quantum, min_quantum, def_quantum, lim_quantum, rate_quantum;
 	uint32_t n_rates, def_rate;
-	bool freewheel = false, global_force_rate, global_force_quantum;
+	bool freewheel, global_force_rate, global_force_quantum, transport_start;
 	struct spa_list collect;
 
 	pw_log_info("%p: busy:%d reason:%s", context, impl->recalc, reason);
@@ -1233,6 +1233,8 @@ int pw_context_recalc_graph(struct pw_context *context, const char *reason)
 
 again:
 	impl->recalc = true;
+	freewheel = false;
+	transport_start = false;
 
 	/* clean up the flags first */
 	spa_list_for_each(n, &context->node_list, link) {
@@ -1574,12 +1576,20 @@ again:
 
 		/* first change the node states of the followers to the new target */
 		spa_list_for_each(s, &n->follower_list, follower_link) {
+			if (s->transport)
+				transport_start = true;
 			if (s == n)
 				continue;
 			pw_log_debug("%p: follower %p: active:%d '%s'",
 					context, s, s->active, s->name);
 			ensure_state(s, running);
 		}
+
+		SPA_ATOMIC_STORE(n->rt.target.activation->command,
+				transport_start ?
+					PW_NODE_ACTIVATION_COMMAND_START :
+					PW_NODE_ACTIVATION_COMMAND_STOP);
+
 		/* now that all the followers are ready, start the driver */
 		ensure_state(n, running);
 	}

src/pipewire/impl-node.c

@@ -938,7 +938,7 @@ static void check_properties(struct pw_impl_node *node)
 	const char *str, *recalc_reason = NULL;
 	struct spa_fraction frac;
 	uint32_t value;
-	bool driver, trigger;
+	bool driver, trigger, transport;
 	struct match match;
 
 	match = MATCH_INIT(node);
@@ -1021,6 +1021,13 @@ static void check_properties(struct pw_impl_node *node)
 		recalc_reason = "link group changed";
 	}
 
+	transport = pw_properties_get_bool(node->properties, PW_KEY_NODE_TRANSPORT, false);
+	if (transport != node->transport) {
+		pw_log_info("%p: transport %d -> %d", node, node->transport, transport);
+		node->transport = transport;
+		recalc_reason = "transport changed";
+	}
+
 	if ((str = pw_properties_get(node->properties, PW_KEY_MEDIA_CLASS)) != NULL &&
 	    (strstr(str, "/Sink") != NULL || strstr(str, "/Source") != NULL)) {
 		node->can_suspend = true;

src/pipewire/keys.h

@@ -139,6 +139,7 @@ extern "C" {
 								  *  in the same group are always scheduled
 								  *  with the same driver. Can be an array of
 								  *  group names. */
+#define PW_KEY_NODE_TRANSPORT		"node.transport"	/**< if the transport is active or not */
 #define PW_KEY_NODE_EXCLUSIVE		"node.exclusive"	/**< node wants exclusive access to resources */
 #define PW_KEY_NODE_AUTOCONNECT		"node.autoconnect"	/**< node wants to be automatically connected
 								  *  to a compatible node */

src/pipewire/private.h

@@ -683,6 +683,7 @@ struct pw_impl_node {
 					  *  trigger to start processing. */
 	unsigned int can_suspend:1;
 	unsigned int checked;		/**< for sorting */
+	unsigned int transport:1;	/**< the transport is active */
 
 	uint32_t port_user_data_size;	/**< extra size for port user data */