E1000_MDICNFG_EXT_MDIO
ext_mdio = !!(reg & E1000_MDICNFG_EXT_MDIO);
mdicnfg |= E1000_MDICNFG_EXT_MDIO;
reg_val = mdicnfg & ~E1000_MDICNFG_EXT_MDIO;