UMIDI_TX_TRANSFER
if (chan->xfer[UMIDI_TX_TRANSFER] == NULL) {
usbd_transfer_start(chan->xfer[UMIDI_TX_TRANSFER]);
usbd_transfer_stop(chan->xfer[UMIDI_TX_TRANSFER]);
if (chan->xfer[UMIDI_TX_TRANSFER] == NULL &&
if (chan->xfer[UMIDI_TX_TRANSFER] != NULL &&
usbd_xfer_maxp_was_clamped(chan->xfer[UMIDI_TX_TRANSFER]))
[UMIDI_TX_TRANSFER] = {