UHSO_CTRL_READ
sc->sc_tty[mux].ht_xfer[UHSO_CTRL_READ],
usbd_transfer_start(sc->sc_tty[mux].ht_xfer[UHSO_CTRL_READ]);
sc->sc_tty[ucom->sc_subunit].ht_xfer[UHSO_CTRL_READ]);
[UHSO_CTRL_READ] = {