VID_C_INT_STAT
s = bus_space_read_4(sc->sc_memt, sc->sc_memh, VID_C_INT_STAT);
bus_space_write_4(sc->sc_memt, sc->sc_memh, VID_C_INT_STAT, s);
bus_space_write_4(sc->sc_memt, sc->sc_memh, VID_C_INT_STAT, 0);