static int l2cap_parse_conf_req(struct l2cap_chan *chan, void *data, size_t data_size)
{
	struct l2cap_conf_rsp *rsp = data;
	void *ptr = rsp->data;
	void *endptr = data + data_size;
	void *req = chan->conf_req;
	int len = chan->conf_len;
	int type, hint, olen;
	unsigned long val;
	struct l2cap_conf_rfc rfc = { .mode = L2CAP_MODE_BASIC };
	struct l2cap_conf_efs efs;
	u8 remote_efs = 0;
	u16 mtu = L2CAP_DEFAULT_MTU;
	u16 result = L2CAP_CONF_SUCCESS;
	u16 size;

	BT_DBG("chan %p", chan);

	while (len >= L2CAP_CONF_OPT_SIZE) {
		len -= l2cap_get_conf_opt(&req, &type, &olen, &val);
		if (len < 0)
			break;

		hint  = type & L2CAP_CONF_HINT;
		type &= L2CAP_CONF_MASK;

		switch (type) {
		case L2CAP_CONF_MTU:
			if (olen != 2)
				break;
			mtu = val;
			break;

		case L2CAP_CONF_FLUSH_TO:
			if (olen != 2)
				break;
			chan->flush_to = val;
			break;

		case L2CAP_CONF_QOS:
			break;

		case L2CAP_CONF_RFC:
			if (olen != sizeof(rfc))
				break;
			memcpy(&rfc, (void *) val, olen);
			break;

		case L2CAP_CONF_FCS:
			if (olen != 1)
				break;
			if (val == L2CAP_FCS_NONE)
				set_bit(CONF_RECV_NO_FCS, &chan->conf_state);
			break;

		case L2CAP_CONF_EFS:
			if (olen != sizeof(efs))
				break;
			remote_efs = 1;
			memcpy(&efs, (void *) val, olen);
			break;

		case L2CAP_CONF_EWS:
			if (olen != 2)
				break;
			if (!(chan->conn->local_fixed_chan & L2CAP_FC_A2MP))
				return -ECONNREFUSED;
			set_bit(FLAG_EXT_CTRL, &chan->flags);
			set_bit(CONF_EWS_RECV, &chan->conf_state);
			chan->tx_win_max = L2CAP_DEFAULT_EXT_WINDOW;
			chan->remote_tx_win = val;
			break;

		default:
			if (hint)
				break;
			result = L2CAP_CONF_UNKNOWN;
			*((u8 *) ptr++) = type;
			break;
		}
	}

	if (chan->num_conf_rsp || chan->num_conf_req > 1)
		goto done;

	switch (chan->mode) {
	case L2CAP_MODE_STREAMING:
	case L2CAP_MODE_ERTM:
		if (!test_bit(CONF_STATE2_DEVICE, &chan->conf_state)) {
			chan->mode = l2cap_select_mode(rfc.mode,
						       chan->conn->feat_mask);
			break;
		}

		if (remote_efs) {
			if (__l2cap_efs_supported(chan->conn))
				set_bit(FLAG_EFS_ENABLE, &chan->flags);
			else
				return -ECONNREFUSED;
		}

		if (chan->mode != rfc.mode)
			return -ECONNREFUSED;

		break;
	}

done:
	if (chan->mode != rfc.mode) {
		result = L2CAP_CONF_UNACCEPT;
		rfc.mode = chan->mode;

		if (chan->num_conf_rsp == 1)
			return -ECONNREFUSED;

		l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
				   (unsigned long) &rfc, endptr - ptr);
	}

	if (result == L2CAP_CONF_SUCCESS) {
		/* Configure output options and let the other side know
		 * which ones we don't like. */

		if (mtu < L2CAP_DEFAULT_MIN_MTU)
			result = L2CAP_CONF_UNACCEPT;
		else {
			chan->omtu = mtu;
			set_bit(CONF_MTU_DONE, &chan->conf_state);
		}
		l2cap_add_conf_opt(&ptr, L2CAP_CONF_MTU, 2, chan->omtu, endptr - ptr);

		if (remote_efs) {
			if (chan->local_stype != L2CAP_SERV_NOTRAFIC &&
			    efs.stype != L2CAP_SERV_NOTRAFIC &&
			    efs.stype != chan->local_stype) {

				result = L2CAP_CONF_UNACCEPT;

				if (chan->num_conf_req >= 1)
					return -ECONNREFUSED;

				l2cap_add_conf_opt(&ptr, L2CAP_CONF_EFS,
						   sizeof(efs),
						   (unsigned long) &efs, endptr - ptr);
			} else {
				/* Send PENDING Conf Rsp */
				result = L2CAP_CONF_PENDING;
				set_bit(CONF_LOC_CONF_PEND, &chan->conf_state);
			}
		}

		switch (rfc.mode) {
		case L2CAP_MODE_BASIC:
			chan->fcs = L2CAP_FCS_NONE;
			set_bit(CONF_MODE_DONE, &chan->conf_state);
			break;

		case L2CAP_MODE_ERTM:
			if (!test_bit(CONF_EWS_RECV, &chan->conf_state))
				chan->remote_tx_win = rfc.txwin_size;
			else
				rfc.txwin_size = L2CAP_DEFAULT_TX_WINDOW;

			chan->remote_max_tx = rfc.max_transmit;

			size = min_t(u16, le16_to_cpu(rfc.max_pdu_size),
				     chan->conn->mtu - L2CAP_EXT_HDR_SIZE -
				     L2CAP_SDULEN_SIZE - L2CAP_FCS_SIZE);
			rfc.max_pdu_size = cpu_to_le16(size);
			chan->remote_mps = size;

			__l2cap_set_ertm_timeouts(chan, &rfc);

			set_bit(CONF_MODE_DONE, &chan->conf_state);

			l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC,
					   sizeof(rfc), (unsigned long) &rfc, endptr - ptr);

			if (test_bit(FLAG_EFS_ENABLE, &chan->flags)) {
				chan->remote_id = efs.id;
				chan->remote_stype = efs.stype;
				chan->remote_msdu = le16_to_cpu(efs.msdu);
				chan->remote_flush_to =
					le32_to_cpu(efs.flush_to);
				chan->remote_acc_lat =
					le32_to_cpu(efs.acc_lat);
				chan->remote_sdu_itime =
					le32_to_cpu(efs.sdu_itime);
				l2cap_add_conf_opt(&ptr, L2CAP_CONF_EFS,
						   sizeof(efs),
						   (unsigned long) &efs, endptr - ptr);
			}
			break;

		case L2CAP_MODE_STREAMING:
			size = min_t(u16, le16_to_cpu(rfc.max_pdu_size),
				     chan->conn->mtu - L2CAP_EXT_HDR_SIZE -
				     L2CAP_SDULEN_SIZE - L2CAP_FCS_SIZE);
			rfc.max_pdu_size = cpu_to_le16(size);
			chan->remote_mps = size;

			set_bit(CONF_MODE_DONE, &chan->conf_state);

			l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
					   (unsigned long) &rfc, endptr - ptr);

			break;

		default:
			result = L2CAP_CONF_UNACCEPT;

			memset(&rfc, 0, sizeof(rfc));
			rfc.mode = chan->mode;
		}

		if (result == L2CAP_CONF_SUCCESS)
			set_bit(CONF_OUTPUT_DONE, &chan->conf_state);
	}
	rsp->scid   = cpu_to_le16(chan->dcid);
	rsp->result = cpu_to_le16(result);
	rsp->flags  = cpu_to_le16(0);

	return ptr - data;
}