Bluetooth: fix HCI ISO Data packets fragmentation

this commit partially reverts e460847

According to Core Spec 5.4, Vol. 4, Part E, 5.4.5, Data_Total_Length field
contains length of the whole packet including optional fields of SDU
(Time_Stamp, Packet_Sequence_Number, ISO_SDU_Length, RFU and
Packet_Status_Flag). In Zephyr Host, Data_Total_Length value
is stored in bt_dev.le.iso_mtu field.
Therefore, there is no need to calculate iso_hdr_len(),
this length is already taken into account in conn_mtu(conn).

This commits removes iso_hdr_len() function and fixes
calculation of HCI ISO Data packet length calculations.

Signed-off-by: Ivan Iushkov <[email protected]>

Author: ivaniushkov

subsys/bluetooth/host/conn.c

@@ -656,21 +656,6 @@ static int do_send_frag(struct bt_conn *conn, struct net_buf *buf, uint8_t flags
 	return err;
 }
 
-static size_t iso_hdr_len(struct net_buf *buf, struct bt_conn *conn)
-{
-#if defined(CONFIG_BT_ISO)
-	if (conn->type == BT_CONN_TYPE_ISO) {
-		if (tx_data(buf)->iso_has_ts) {
-			return BT_HCI_ISO_TS_DATA_HDR_SIZE;
-		} else {
-			return BT_HCI_ISO_DATA_HDR_SIZE;
-		}
-	}
-#endif
-
-	return 0;
-}
-
 static int send_frag(struct bt_conn *conn,
 		     struct net_buf *buf, struct net_buf *frag,
 		     uint8_t flags)
@@ -683,9 +668,7 @@ static int send_frag(struct bt_conn *conn,
 
 	/* Add the data to the buffer */
 	if (frag) {
-		size_t iso_hdr = flags == FRAG_START ? iso_hdr_len(buf, conn) : 0;
-		uint16_t frag_len = MIN(conn_mtu(conn) + iso_hdr,
-					net_buf_tailroom(frag));
+		uint16_t frag_len = MIN(conn_mtu(conn), net_buf_tailroom(frag));
 
 		net_buf_add_mem(frag, buf->data, frag_len);
 		net_buf_pull(buf, frag_len);
@@ -733,11 +716,6 @@ static struct net_buf *create_frag(struct bt_conn *conn, struct net_buf *buf)
 	return frag;
 }
 
-static bool fits_single_ctlr_buf(struct net_buf *buf, struct bt_conn *conn)
-{
-	return buf->len - iso_hdr_len(buf, conn) <= conn_mtu(conn);
-}
-
 static int send_buf(struct bt_conn *conn, struct net_buf *buf)
 {
 	struct net_buf *frag;
@@ -747,7 +725,7 @@ static int send_buf(struct bt_conn *conn, struct net_buf *buf)
 	LOG_DBG("conn %p buf %p len %u", conn, buf, buf->len);
 
 	/* Send directly if the packet fits the ACL MTU */
-	if (fits_single_ctlr_buf(buf, conn) && !tx_data(buf)->is_cont) {
+	if (buf->len <= conn_mtu(conn) && !tx_data(buf)->is_cont) {
 		LOG_DBG("send single");
 		return send_frag(conn, buf, NULL, FRAG_SINGLE);
 	}