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DP83867IS: Communication error

NAOKI AOYAMA
Guru 11215 points
Part Number: DP83867IS

Hello,

Our customer use the DP83867IS, with SGMII.

It occur communication error. The signal of the MDC, MDIO and TD_x_x are correct,

but there is no data at SGMII_SON, SGMII_SOP, SGMII_SIN and SGMII_SIP.

The setting of the customer as below.

 Connect their board to PC

 PHY address : 3

 Using SGMII MAC Interface

 Enable Auto Negotiation

 PC speed : 1000Mbps , Full-Duplex

They checked the register data dump. The AUTO-NEGOTIATION COMPLETE bit of the BMSR is High,

but the SGMII_AUTONEG_COMPLETE bit is Low.

Does it need the SGMII_AUTONEG_COMPLETE bit High for the correct communication?

I attach the register data dump file. It is the data when the issue occurred.

DP83867_Register_data_dump.pdf

Best Regards,

Naoki Aoyama

  • 0
    TI__Mastermind 19780 points
    Hi Naoki,

    Your registers appear to be normal.

    There may be a problem with SGMII auto-negotiation setting mismatch. SGMII auto-negotiation is initiated by the PHY. The PHY transmits information about the link once the link is up. The MAC then responds with an acknowledge bit.

    If the MAC has SGMII auto-negotiation disabled, the acknowledge bit will never be sent to the PHY, and the PHY will not set auto-negotiation as done.

    Please verify the MAC is set to SGMII mode and SGMII auto negotiation is enabled.

    Best Regards,
  • 0 in reply to Rob Rodrigues
    Guru 11215 points
    Hello Rob,

    Thank you for your reply.
    I will ask the customer to check the configuration of the MAC.
    When I get a result, I will let you know.

    Best Regards,
    Naoki Aoyama
  • 0 in reply to Rob Rodrigues
    Guru 11215 points
    Hi Rob,

    Now the customer are checking the setting of the MAC.
    They also refer to the Troubleshotting Guide, have a question.

    It is mentioned at 2.10 Establish an SGMII Link as follows,

    • When establishing an SGMII connection between the MAC and the PHY,.......
    ...... If Auto-Negotiation is not used, both the MAC and the PHY must be
    forced to the same speed and duplex configuration.

    "If Auto-Negotiation is not used," means both the MAC and PHY do not use
    Auto_Negotiation. Is may understanding correct?

    They want to know the mechanism of the Auto_Negotiation.
    Do you have any documents about it?

    Best Regards,
    Naoki Aoyama
  • 0 in reply to NAOKI AOYAMA
    TI__Mastermind 19780 points
    Hi Naoki,

    "If Auto-Negotiation is not used," means both the MAC and PHY do not use
    Auto_Negotiation. Is may understanding correct? [Rob] Yes, you are correct. Both sides must be configured the same way. It is possible that the PHY is configured to enable auto-negotiation and MAC is configured to disable auto-negotiation. Then no SGMII link will be created.

    The auto-negotiation mechanism of SGMII is discussed briefly in section 8.4.1.1 of the DP83867IS datasheet.

    More details are in the SGMII specification which can be found using Google. From the SGMII specification v1.8, please look at the "Control Information Exchanged Between Links" section.

    Best Regards,
  • 0 in reply to Rob Rodrigues
    Guru 11215 points
    Hi Rob,

    Thank you for your reply.
    I will feedback the customer to refer the SGMII specification.

    Best Regards,
    Naoki Aoyama