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Can't get Ethernet receive to work on DM8148

Stephen Turner
Genius 3476 points

Hi

We have a design based on the DM8148 and a Vitesse VSC8601 Gigabit PHY.  Our design currently boots u-boot via an SD card. 

Our problem is that the ethernet interface appears to transmit but not receive network traffic.  We know it transmits as we can issue the "dhcp" command from u-boot and see the DHCP_Discover message in Wireshark.  Our DHCP server (TFTPD32) sends a DHCP_Offer back, but the DM8148 never seems to receive it, so an IP address is never assigned.

We have tried with both 100Mb and 1Gb links, with the same result

We think we have the PHY hooked up correctly (double checked our schematic and PCB layout) and do see RGMII data coming from the PHY going to the DM8148 EMAC0.

Is there some register we can look at in u-boot to see if we are even getting ethernet frames into the EMAC?.

thanks

steve

  • 0
    Genius 3476 points

    Would the following 3PSW register be a good place to start looking?.  Does the stats collection need to be enabled/

    400h RXGOODFRAMES CPSW_STATS Total number of good frames received

    thanks

  • 0 in reply to Stephen Turner
    Genius 3476 points

    On page 1246 of the Feb 2012 DM8148 TRM, the picture of the CPSW/3PSW clocking states that the RGMII 250MHz ref clock needs to be exactly 250MHz. 

    Why is this?. What is it used for?.  To generate the RGMII transmit side clocks?.

    Does it affect the RGMII receive side?.

    -steve

  • 0 in reply to Stephen Turner
    Genius 3476 points

    OK, we found our problem.  It was the RGMII clock skew.  The receive side didn't seem to have any.  We enabled it on the VSC8601 PHY and all is good!

    -steve

  • 0 in reply to Stephen Turner
    Intellectual 755 points

    Hi,

    We are using DM8148 processor on our board. We are using EMAC1 for our Ethernet interface . The data rate transfer happens only for 100Mbps.When we try setting our PC to 1000Mbps using mii-tool eth0 -r command and then do dhcp , auto negotiation happens and the speed will be reduced to 100Mbps automatically and the data transfer takes place. Same is the problem with 10Mbps. Our PC supports 10/100/1000Mbps speed.

    Please can someone help us on this?

    Thanks

    Prakash