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DRA821U: DRA821:DP83822I Turning off auto-negotiation (100Mbps)

Swapna yendrapalli
Intellectual 625 points
Part Number: DRA821U
Other Parts Discussed in Thread: DP83822I, DRA821

Hi,

We are using DP83822I phy interfaced with DRA821 processor (CPSW5G) and would like to know the procedure to turn off auto-negotiation mode ?

Environment - TI-SDK 8.1 + QNX + RTOS setup

Currently, the interface works with auto-negotiation enabled in RMII mode but when we disable auto-negotiation on PHY side(DP89822I )link is down.

  • How can we dump the phy registers connected to the 5 port switch?
  • Are there any registers on the processor side(dra821) to disable auto-negotiation?

Thanks,

Swapna

  • 0
    TI__Mastermind 38910 points

    Hi Swapna,

    Swapna yendrapalli said:
    How can we dump the phy registers connected to the 5 port switch?

    Are you able to connect to CCS for debug? We have a debug gel to print the phy registers using mdio.

    Swapna yendrapalli said:
    Are there any registers on the processor side(dra821) to disable auto-negotiation?

    We do not have auto-negotiation for MAC. I am not sure what the ask is here. can you elaborate here why and what exactly you want to do.

    Regards,
    Tanmay

  • 0 in reply to Tanmay Patil
    Intellectual 625 points

    Thanks Tanmay!

    • Any tools to dump the PHY registers from QNX/RTOS cmd line? We will see if we can connect to CCS on the customer board.
    • Are there any registers on the processor side(dra821) to disable auto-negotiation?
      • Currently, our board works fine with auto-negotiation enabled on PHY side. Could you please let us know the procedure to operate the PHY in forced 100Mbps full duplex mode ? We tried setting  phy register 0 to 0x2100 after reset but link is down.
      • The reason for asking about the controller side auto-negotiation flag is we saw MR_AN_ENABLE for SGMII but we didn't see similar register for RMII
  • 0 in reply to Swapna yendrapalli
    TI__Mastermind 38910 points

    Hi Swapna,

    Swapna yendrapalli said:
    The reason for asking about the controller side auto-negotiation flag is we saw MR_AN_ENABLE for SGMII but we didn't see similar register for RMII

    Things are different for SGMII and RGMII/RMII. There is no option of disabling autonegotiation for RGMII/RMII

    Swapna yendrapalli said:
    Could you please let us know the procedure to operate the PHY in forced 100Mbps full duplex mode ?

    That has to set by phy driver. Weather the phy has autonegotiation enabled/disabled does not matter to MAC. The thing to take care about is that the link partner should also have its autonegotiation disabled in this case.

    Regards,
    Tanmay

  • 0 in reply to Tanmay Patil
    Intellectual 625 points

    Thanks Tanmay!

    That has to set by phy driver. Weather the phy has autonegotiation enabled/disabled does not matter to MAC. The thing to take care about is that the link partner should also have its autonegotiation disabled in this case.

    Could you please let us know the PHY initialization sequence/register dump to set PHY to RMII mode with auto-negotiation disabled( 100Mbps, Full duplex operation) so we can cross-check the register values?

  • +1 in reply to Swapna yendrapalli
    Intellectual 625 points

    We found bootstrap settings for the below register enabled and disabling this manually enabled link.