Bluetooth: Ignore BR/EDR packet size constraints when fragmenting for AMP

When operating over BR/EDR, ERTM accounts for the maximum over-the-air
packet size when setting the PDU size.  AMP controllers do not use the
same over-the-air packets, so the PDU size should only be based on the
HCI MTU of the AMP controller.

Signed-off-by: Mat Martineau <mathewm@codeaurora.org>
Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

net/bluetooth/l2cap_core.c

@@ -2272,7 +2272,9 @@ static int l2cap_segment_sdu(struct l2cap_chan *chan,
 	/* PDU size is derived from the HCI MTU */
 	pdu_len = chan->conn->mtu;
 
-	pdu_len = min_t(size_t, pdu_len, L2CAP_BREDR_MAX_PAYLOAD);
+	/* Constrain PDU size for BR/EDR connections */
+	if (!chan->hs_hcon)
+		pdu_len = min_t(size_t, pdu_len, L2CAP_BREDR_MAX_PAYLOAD);
 
 	/* Adjust for largest possible L2CAP overhead. */
 	if (chan->fcs)