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Linux/AM4376: Ethernet port LED issue

Jimmy Ni
Prodigy 30 points
Part Number: AM4376


Tool/software: Linux

Hi, we got some LED issue with AM4376 this IC when we tried to restart in Linux system.

We designed the MB with AM4376 and our LAN IC is KSZ9031RNX as recommanded, it works fine for every time we boot the system, also the LED from the LAN port is normal,

but when we try to restart the system, some of LAN port LED will keep Flashing (We found the same issue happened with TI development board as well)

Do you have any solution for this issue?

By the way, can you let me know how to change the definition of LAN port LED?

For example, when it link up --> Light on and during communication --> LED Flashing

Thanks for your help!

  • 0
    TI__Guru**** 393215 points
    Please post which Linux version you use.
  • 0 in reply to Biser Gatchev-XID
    Prodigy 30 points
    Hi, the Linux kernel version is 4.9.69, thanks!
  • 0 in reply to Jimmy Ni
    TI__Mastermind 40690 points
    Hi,

    There are two LEDs typically on the connector. A link light and a data traffic light. The data traffic light will typically blink as traffic occurs and remain solid where there is not any traffic. I have seen several different types of usages on the LEDs. These signals that control the LEDs are connected to the PHY so I will have to recommend that you contact the PHY manufacturer for more details on how it would interact with the connector LEDs.

    Best Regards,
    Schuyler
  • 0 in reply to Schuyler Patton
    Prodigy 30 points
    Hi, Thanks for your reply! I'll check with PHY manufacturer for more details
    but about my first question, I still no idea why the LED became abnormal when system restart in Linux OS
    Even we found the same issue happened with TI's development board (AM4376 with same PHY chip)
    Do you have any idea or solution for that? Thanks!
  • 0 in reply to Jimmy Ni
    TI__Mastermind 40690 points
    Hi,

    I am not sure which LED you are mentioning but if it is the traffic indicator LED then any network traffic would cause it to blink. The PHY documentation should, well hopefully, describes what the two LED indicators represent in terms of link detection and network traffic and what the flashing would mean.

    I tried the AM437x IDK and used the CPSW port. I pinged the IDK from another network device and I see the data activity LED flashing during the reboot process. To me this is normal, the PHY is indicating that it is seeing traffic independent of whether or not the processor is receiving packets. Please note the PHY will auto-negotiate links to a link speed and duplex mode independent of software configuration of the MAC on the processor. Once auto-negotiation completes the PHY can receive packets and this reception will cause the traffic LED to blink.

    Best Regards,
    Schuyler