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Linux/DP83822IF: Software for internal loop-back test needed

Roger Newbould31
Intellectual 310 points
Part Number: DP83822IF

Tool/software: Linux

Hi

We have connected the DP83822IF via MII to a MAC and for verification purposes we would like to utilize the built-in loopback capabilities of the PHY.

Is there some kind of special software (Linux) needed to use the loopback test?

Thanks and best regards,
Roger

  • 0
    TI__Mastermind 23675 points
    Hi Roger,

    You can enable the loopback using register access. The Linux driver does not have this function, however you can implement it with a single register write.
    Please see this app note: www.ti.com/.../snla266.pdf
  • 0 in reply to Ross Pimentel
    Intellectual 310 points
    Hi Ross
    Thanks for link to the app note.
    I was referring to software using the loopback function of the PHY, not configuring the PHY itself. Software generating traffic onto the MII interface which is then internally looped back. How do I use the loopback function of the PHY?

    Best regards,
    Roger
  • 0 in reply to Roger Newbould31
    TI__Mastermind 23675 points
    Hi Roger,

    You can send any type of traffic from your MAC to the PHY with the internal MII loopback enabled.
    I have seen customers us iperf for this type of test since a ping won't work.
    You could also try using a tool like ostinato.
  • 0 in reply to Ross Pimentel
    Intellectual 310 points

    Hi Ross

    Thanks for the hint. Do you have further information on how to set up iperf under Linux?

    Thanks.

    Regards,

    Roger

  • 0
    TI__Mastermind 23675 points
    Hi Arakan,

    There are tutorials online for using iperf.

    Are you looking to figure out how to enable a loopback (i.e. what the register setting is)?
    Or when to use a loopback in a system check?

    In the app note, there is information on how to set the register to enable the loopback.
    Also, in the app note, there is a description for each one on how the loopback works.

    If you are trying to verify the xMII connection, then you would most likely use an analog or xMII loopback.
    If you are trying to verify an error free link with a link partner, then you could use a reverse loopback and have the link partner transmit data to you so that you loop that data back before it goes to the local MAC.