tx_doorbell
bus_addr_t tx_doorbell;
tx->tx_doorbell = MCX_WQ_DOORBELL_BASE +
tx->tx_doorbell);
tx->tx_doorbell, sizeof(uint32_t), BUS_DMASYNC_PREWRITE);
tx->tx_doorbell, sizeof(uint32_t), BUS_DMASYNC_POSTWRITE);
tx->tx_doorbell, sizeof(uint32_t), BUS_DMASYNC_POSTWRITE);
htobem32(MCX_DMA_OFF(&sc->sc_doorbell_mem, tx->tx_doorbell),
tx->tx_doorbell, sizeof(uint32_t), BUS_DMASYNC_PREWRITE);