ALC_MBOX_RD0_PROD_IDX
CSR_WRITE_2(sc, ALC_MBOX_RD0_PROD_IDX,
CSR_WRITE_4(sc, ALC_MBOX_RD0_PROD_IDX,
CSR_WRITE_4(sc, ALC_MBOX_RD0_PROD_IDX, 1);
if (CSR_READ_4(sc, ALC_MBOX_RD0_PROD_IDX) == 0)
CSR_WRITE_4(sc, ALC_MBOX_RD0_PROD_IDX, sc->alc_cdata.alc_rx_cons);