SDMA_INTR_RXBUF
sdma_imask &= ~SDMA_INTR_RXBUF(sc->sc_unit);
SDMA_INTR_RXBUF(sc->sc_unit) |
if (icause & SDMA_INTR_RXBUF(sc->sc_unit)) {
icause &= ~SDMA_INTR_RXBUF(sc->sc_unit);
sdma_imask |= SDMA_INTR_RXBUF(sc->sc_unit);