Hi , I have partially ported Uboot on one of our MPC8540 based custom boards. I am currently facing problems in bringing up the 10/100Mbps FEC interface. We are using the LXT971A PHY for the FEC interface. Well the problem is that , the MAC is putting out the data but the PHY is failing to put the data on the line. The PHY is successfully able to auto- negotiate. The MAC putting out data was confirmed by the MAC debug registers and by probing the Tx_EN,clock and TX_D lines. I carried out the MAC loop back test which passed . Then went on
for the PHY internal loop back test. Well, when the loop back is enabled the MAC fails to transmit the frame successfully. The thing confusing me is that why the MAC frame transmission is getting affected when i enable the PHY loopback test. Any pointers will be very helpful.
Regards, Girish