U3G_BULK_RD
[U3G_BULK_RD] = {
usbd_xfer_set_stall(sc->sc_xfer[nports][U3G_BULK_RD]);
usbd_transfer_start(sc->sc_xfer[ucom->sc_subunit][U3G_BULK_RD]);
usbd_transfer_stop(sc->sc_xfer[ucom->sc_subunit][U3G_BULK_RD]);