RFCOMM_DEFAULT_MTU
d->mtu = RFCOMM_DEFAULT_MTU;
s->mtu = RFCOMM_DEFAULT_MTU;
sk->sk_sndbuf = RFCOMM_MAX_CREDITS * RFCOMM_DEFAULT_MTU * 10;
sk->sk_rcvbuf = RFCOMM_MAX_CREDITS * RFCOMM_DEFAULT_MTU * 10;