From 6fcb06a28d150095f042c477fbe20a9767d9a951 Mon Sep 17 00:00:00 2001 From: Andre Guedes Date: Thu, 31 May 2012 17:01:33 -0300 Subject: [PATCH] Bluetooth: Change default MTU for L2CAP ATT channel This patch changes the default MTU value for L2CAP ATT fixed channel to L2CAP_DEFAULT_MTU (672 octets). Differently from others L2CAP channels, in L2CAP ATT fixed channel there is no MTU negotiation. The MTU value for that channel is up to the L2CAP implementation. The only restriction in L2CAP spec is the MTU value must not be less than 23 octets. At ATT protocol level (on top of L2CAP), we have the ATT_MTU which defines the maximum size of any ATT message sent between client and server. GATT profile defines ATT_MTU default value to 23 octets. If a GATT based profile wants to use ATT_MTU greater than 23 octets (e.g. HID over GATT profile), it should negotiate a new value by executing the GATT Exchange MTU sub-procedure. Thus, in order to support any value of ATT_MTU negotiated at ATT protocol level, our L2CAP implementation should have L2CAP ATT fixed channel MTU equal or greater than ATT_MAX_MTU (512 octets). Signed-off-by: Andre Guedes Signed-off-by: Gustavo Padovan --- net/bluetooth/l2cap_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c index 9750204011c6..f9bffe3af026 100644 --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -449,7 +449,7 @@ static void __l2cap_chan_add(struct l2cap_conn *conn, struct l2cap_chan *chan) case L2CAP_CHAN_CONN_ORIENTED: if (conn->hcon->type == LE_LINK) { /* LE connection */ - chan->omtu = L2CAP_LE_DEFAULT_MTU; + chan->omtu = L2CAP_DEFAULT_MTU; chan->scid = L2CAP_CID_LE_DATA; chan->dcid = L2CAP_CID_LE_DATA; } else { -- 2.30.2