G_AUDIO_N_TRANSFER
static const struct usb_config g_audio_config[G_AUDIO_N_TRANSFER] = {
G_AUDIO_N_TRANSFER, sc, &sc->sc_lock);
usbd_transfer_unsetup(sc->sc_xfer, G_AUDIO_N_TRANSFER);
struct usb_xfer *sc_xfer[G_AUDIO_N_TRANSFER];