IM_TX_EMPTY_INT
sc->sc_intmask |= IM_TX_INT | IM_TX_EMPTY_INT;
if (status & IM_TX_EMPTY_INT) {
smc91cxx_intr_ack_write(bst, bsh, IM_TX_EMPTY_INT, 0);
mask &= ~IM_TX_EMPTY_INT;
sc->sc_intmask &= ~IM_TX_EMPTY_INT;