Bluetooth: iso: make TX path service all connections

ISO connections that were in the TX queue were not getting serviced in
time. This happens because `iso_data_pull()` returns `NULL` when that
particular connection (`conn`) is done sending.

But it doesn't trigger the TX processor again to process other channels in
the queue. This patch fixes that by calling `bt_tx_irq_raise()`.

We can't do this from `conn.c` as we don't know if the `NULL` returned is
because the current channel is out of data or because it has data but it
can't send it (e.g. the current buf is being "viewed" already).

Fixes #74321

Signed-off-by: Jonathan Rico <[email protected]>

Author: jori-nordic

subsys/bluetooth/host/iso.c

@@ -750,6 +750,9 @@ static struct net_buf *iso_data_pull(struct bt_conn *conn,
 
 	if (!frag) {
 		LOG_DBG("signaled ready but no frag available");
+		/* Service other connections */
+		bt_tx_irq_raise();
+
 		return NULL;
 	}
 
@@ -759,6 +762,9 @@ static struct net_buf *iso_data_pull(struct bt_conn *conn,
 		LOG_DBG("channel has been disconnected");
 		__ASSERT_NO_MSG(b == frag);
 
+		/* Service other connections */
+		bt_tx_irq_raise();
+
 		return NULL;
 	}