MII_CR_SPEED_1000
*phy_ctrl &= ~MII_CR_SPEED_1000;
*phy_ctrl &= ~(MII_CR_SPEED_1000 | MII_CR_SPEED_100);
phy_ctrl |= MII_CR_FULL_DUPLEX | MII_CR_SPEED_1000;
phy_ctrl = MII_CR_FULL_DUPLEX | MII_CR_SPEED_1000 | MII_CR_LOOPBACK;
*phy_ctrl &= ~MII_CR_SPEED_1000;
*phy_ctrl &= ~(MII_CR_SPEED_1000 | MII_CR_SPEED_100);