[U-Boot-Users] LXT971A PHY debugging on MPC8540 Custom Board

Shirasat Girish-ags032 girishjs at motorola.com
Mon Jun 13 19:55:15 CEST 2005

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.


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