PHY_BMCR_100M
control &= ~PHY_BMCR_100M;
control |= PHY_BMCR_100M;
control |= PHY_BMCR_100M;
control &= ~PHY_BMCR_100M;
control = PHY_BMCR_100M | PHY_BMCR_FDX;
control |= PHY_BMCR_100M;
control &= ~PHY_BMCR_100M;