tl_miibus_writereg
static int tl_miibus_writereg (device_t, int, int, int);
DEVMETHOD(miibus_writereg, tl_miibus_writereg),
tl_miibus_writereg(dev, i, MII_BMCR, flags);
tl_miibus_writereg(dev, 31, MII_BMCR, BMCR_ISO);
tl_miibus_writereg(dev, 31, MII_BMCR, BMCR_LOOP|BMCR_ISO);