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Original question:

AM335x Implementing MDIO Bitbang Driver For Clause 45

Linux/DP83867CS: AM335x Implementing MDIO Bitbang Driver For Clause 45

Eryk Druszkiewicz
Prodigy 70 points
Part Number: DP83867CS

Tool/software: Linux

Good day,

Per recommendation from TI's chat support, I am posting this as a related question as normally universities do not have FAEs (?).

I am working on a design that utilizes the AM335x processor and the DP83867CS PHY. 

I am trying to debug why we are observing RX CRC/Align errors. I would like to be able once in the Linux user terminal on the AM335x to inspect the higher  (>31) DP83867CS configuration registers that require the MDIO PHY access with Clause 45 support.

How can I obtain the IP mentioned in the referenced thread (https://e2e.ti.com/support/processors/f/791/t/546577?AM335x-Implementing-MDIO-Bitbang-Driver-For-Clause-45and/or have other ways of getting the desired functionality emerged since the time of the original thread? 

Thank you for your time and help.

  • 0
    TI__Mastermind 19780 points
    Hi Eryk,

    The AM335x CPSW has IP that allows access to clause 22 registers.

    The DP83867CS supports clause 22 access to clause 45 registers using indirect method.

    Please see the DP83867CS datasheet section "8.4.2.1 Extended Address Space Access"

    You will need to use a 4 register read/write sequence to get to the clause 45 register.

    If you have a functioning driver in Linux, that can access the PHY properly, I'd suggest looking for the Linux tool called phytool

    Best Regards,
  • 0 in reply to Rob Rodrigues
    Prodigy 70 points
    Hello Rob,

    Thank you for pointing me to the "Extended Address Space Access", don't know how I missed that.
    Wrote some code and indeed I can now access all the higher registers.

    Thank you.