dmac_prepare_xfer
struct dmac_dma_xfer *dmac_prepare_xfer(struct dmac_channel_stat *,
fdc->sc_xfer = dmac_prepare_xfer(fdc->sc_dmachan, fdc->sc_dmat,
sc->sc_current.xfer = dmac_prepare_xfer(chan, sc->sc_dmat,
sc->sc_current.xfer = dmac_prepare_xfer(chan, sc->sc_dmat,