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DP83TC812S-Q1: SGMII link down

Peter Xu
Expert 6120 points
Part Number: DP83TC812S-Q1

Hi team,

My customer uses 812s in their system and the project is in mass production status now. They found a board that has fault while running. The 0x60A register value was 0x136, which means SGMII link down.
The other register values are as follows:
0x1 > 0x65
0x0871 > The SQI value is 0x7

Then they restart the device, the problem disappears.

They did not get any other data because the fault shows in real car and did not occur again.

Can you give some comment on this? What should we test?

Regards,

Peter

  • 0
    TI__Mastermind 27122 points

    Hi Peter,

    If I am understanding correctly, only 1 board has been found to have this issue? And it only occurred one time and has never occurred again?

    Was the SGMII link down seen immediately after power up or some time after operating for many hours?

    This issue will be difficult to debug if it is not reproducible. We may need the customer's help to narrow down the conditions for occurrence. Was EMI a possible threat in this case?

    Can you also share the schematic for my reference?

    Thanks,

    David

  • 0 in reply to David Creger
    TI__Expert 6120 points

    Hi David,

    David Creger said:
    If I am understanding correctly, only 1 board has been found to have this issue?

    Right.

    David Creger said:
    And it only occurred one time and has never occurred again?

    Yes.

    David Creger said:
    Was the SGMII link down seen immediately after power up or some time after operating for many hours?

    It is not too long after power up.

    David Creger said:
    We may need the customer's help to narrow down the conditions for occurrence. Was EMI a possible threat in this case?

    Yes, my customer wants to know what they should do to narrow down the condition. I don't think EMI is a problem, they usually do the EMI test in DV status.

    David Creger said:
    Can you also share the schematic for my reference?

    I can send you later.

    Regards,

    Peter

  • 0 in reply to Peter Xu
    TI__Mastermind 27122 points

    Hi Peter,

    If the customer can provide a full register dump before and during the fail case, I can have a look at it. I will also have a look at the schematic and layout when you have a chance to share. 

    Can you please check that the following SGMII signal guidelines have been met.

    Thanks,

    David