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BCM53112 external PHY considerations - link status

  • 1.  BCM53112 external PHY considerations - link status

    Posted 12-09-2019 09:42 AM
    Hello Community,

    The external PHY chip is connected to switching chip over MDIO interface.  What are the relevant configurations need to be done in terms of the following points:

    • OTP and Strap configuration (if any required?)
    • Any specific register to be written , e.g. from M7 subsystem registers etc.
    • Apparently the link scan is offloaded to 8051 MCU and is not done by the switching chip directly(?!) Is the 8051 enabled by default? Is auto polling from external PHY is enabled by default on switching chip?

    We have written specifically a register according the reg. ref. manual in order to tell the switching chip to do the scan from external PHY for a specific port bitmap. However, the chip does not respect this and always does the scan from internal PHY?!

    The probe and init functions have already been implemented and the external phy is detected on the BCM diagnostic shell. However, the link up/down events are not detected for the external PHY?!



    Thanks for your support.
    Best Regards,
    Alfie.


  • 2.  RE: BCM53112 external PHY considerations - link status

    Posted 12-13-2019 03:53 AM
    Hi Alfie,
         Basically there is no specific configuration need for the external PHY access. You just need to make sure below configurations are correct,
    • The MDIO connection is correctly between Switch and external PHY
    • The MDIO address be separated and no conflict 
    Then you should access the external phy correctly.
    And one important thing should be noted, the official released software no support external phy link status polling mechanism.
    You must implement the mechanism by yourself, that's why ou observed the link up/down events are not detected for the external PHY.
    Please check the feedback and let me know any unclear/question. Thanks!

    BR
    Chris