UKBD_N_TRANSFER
UKBD_N_TRANSFER, sc, &sc->sc_kbd.kb_lock);
usbd_transfer_unsetup(sc->sc_xfer, UKBD_N_TRANSFER);
struct usb_xfer *sc_xfer[UKBD_N_TRANSFER];
usbd_transfer_poll(sc->sc_xfer, UKBD_N_TRANSFER);
static const struct usb_config ukbd_config[UKBD_N_TRANSFER] = {