Bluetooth: Don't send RFC for Basic Mode if only it is supported

If the remote side doesn't support Enhanced Retransmission Mode neither
Streaming Mode, we shall not send the RFC option.

Some devices that only supports Basic Mode do not understanding the RFC
option. This patch fixes the regression found with these devices.
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/l2cap.c

@@ -2527,6 +2527,10 @@ static int l2cap_build_conf_req(struct sock *sk, void *data)
 		if (pi->imtu != L2CAP_DEFAULT_MTU)
 			l2cap_add_conf_opt(&ptr, L2CAP_CONF_MTU, 2, pi->imtu);
 
+		if (!(pi->conn->feat_mask & L2CAP_FEAT_ERTM) &&
+				!(pi->conn->feat_mask & L2CAP_FEAT_STREAMING))
+			break;
+
 		rfc.mode            = L2CAP_MODE_BASIC;
 		rfc.txwin_size      = 0;
 		rfc.max_transmit    = 0;
@@ -2534,6 +2538,8 @@ static int l2cap_build_conf_req(struct sock *sk, void *data)
 		rfc.monitor_timeout = 0;
 		rfc.max_pdu_size    = 0;
 
+		l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
+							(unsigned long) &rfc);
 		break;
 
 	case L2CAP_MODE_ERTM:
@@ -2546,6 +2552,9 @@ static int l2cap_build_conf_req(struct sock *sk, void *data)
 		if (L2CAP_DEFAULT_MAX_PDU_SIZE > pi->conn->mtu - 10)
 			rfc.max_pdu_size = cpu_to_le16(pi->conn->mtu - 10);
 
+		l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
+							(unsigned long) &rfc);
+
 		if (!(pi->conn->feat_mask & L2CAP_FEAT_FCS))
 			break;
 
@@ -2566,6 +2575,9 @@ static int l2cap_build_conf_req(struct sock *sk, void *data)
 		if (L2CAP_DEFAULT_MAX_PDU_SIZE > pi->conn->mtu - 10)
 			rfc.max_pdu_size = cpu_to_le16(pi->conn->mtu - 10);
 
+		l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
+							(unsigned long) &rfc);
+
 		if (!(pi->conn->feat_mask & L2CAP_FEAT_FCS))
 			break;
 
@@ -2577,9 +2589,6 @@ static int l2cap_build_conf_req(struct sock *sk, void *data)
 		break;
 	}
 
-	l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
-						(unsigned long) &rfc);
-
 	/* FIXME: Need actual value of the flush timeout */
 	//if (flush_to != L2CAP_DEFAULT_FLUSH_TO)
 	//   l2cap_add_conf_opt(&ptr, L2CAP_CONF_FLUSH_TO, 2, pi->flush_to);