URTWN_RXBUFSZ
usbd_setup_xfer(xfer, data, data->buf, URTWN_RXBUFSZ,
URTWN_RXBUFSZ, USBD_SHORT_XFER_OK, USBD_NO_TIMEOUT,
error = usbd_create_xfer(sc->rx_pipe[j], URTWN_RXBUFSZ,