dm8148 phy mii mode cpsw_mdio_read return EIO

     we have a dm8148board that phy use mii mode  .I change the DM8148 uboot code :

1   __raw_writel(0x0,GMII_SEL); 

2  function cpsw_pad_config  i use  /*For PG1.0 we only support GMII Mode, setup gmii0/gmii1 pins here*/

when uboot  up i ping the host pc   error  .in function miiphy_reset  call the cpsw_mdio_read  return EIO  .

have anyone give me some advise?  dm8148  support mii mode have change other ? my uboot version is u-boot-04.04.00.01.