UTOPPY_FRAG_SIZE
error = usbd_create_xfer(sc->sc_out_pipe, UTOPPY_FRAG_SIZE, 0, 0,
error = usbd_create_xfer(sc->sc_in_pipe, UTOPPY_FRAG_SIZE,
thislen = uimin(len, UTOPPY_FRAG_SIZE);
if (thislen != uimin(len, UTOPPY_FRAG_SIZE)) {
requested = thislen = uimin(bytesleft, UTOPPY_FRAG_SIZE);