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Linux/DP83867IR: DP83867IR : MII loopback at u-boot in zcu102EVM

jayalaxmi b c
Intellectual 320 points
Part Number: DP83867IR

Tool/software: Linux

Hi All,

I am using ZCU102 development kit. The phy chip used in this is TI DP83867IR.  ZCU102 has GEM(Gigabit Ethernet Mode) controller. I want to validate the MAC to PHY communication. Tried below registers settings(values) by referring  for both GEM and PHY data sheets, but  MII loopback  is not working. After loopback transmitted data is not received at destination location.

PHY address is 0x0c and GEM controller is 0xFF0E000.

Steps :

For DP83867 

After power-on I stop booting at U-boot and issue  "mii read/write" commands to set and read  Phy registers.

Register   ---    values   

0x00(BMCR)  ---   0x5140   -  MII loopback enabled

0xFE(LOOPCR)  --- 0xE720  --  

0x16(BISCR) ---- 0x0000       --- disable other loopback methods.

################################################

For GEM controller :

0xFF0E0000 (control register) -- 0x0000021C  (To enable Rx, Tx, and Management port enable)

0x FF0E0004(config register) --  0x08280400  (To enable PC_select, SGMII mode enable and Gigabit mode enable)

0x0FF0E1C ( transmit_q_ptr ) -- transmitter memory pointer - where transmit data is saved)

0x0FF0E18 ( receive_q_ptr ) -- Receiver memory pointer - To receive data from loopback)

Could you please look into my steps and guide me if I am missing anything or followed steps are correct or not.

Thanks and Regards,

Jayalaxmi

  • 0
    TI__Expert 5670 points
    Hi Jayalaxmi,

    Please refer to this app note for more info on how to use different loopback modes to verify MAC-PHY interface: www.ti.com/.../snla246a.pdf

    Regards,

    Hung Nguyen
  • 0 in reply to Hung Nguyen92
    Intellectual 320 points

    Hi Hung,

    Thanks for the reply. I have set for the digital loop-back as explained in the above mentioned document.

    As mentioned in the document

    "Once loopback is configured, packets can be transmitted from the MAC to verify the MAC interface."

    Could you please tell me how to confirm at u-boot.

    Thanks and Regards,

    Jayalaxmi

  • 0 in reply to jayalaxmi b c
    TI__Expert 5670 points
    Hi Jayalaxmi,

    First of all, TI will not look into u-code of a non-TI device. You need to contact respective vendor for support and confirmation.

    On the PHY side, try the following for digital loopback:
    1. Write register 0x0000 to 0x0140 to force 1000BASE-T operation.
    2. Write register 0x0016 to 0x0004 to enable digital loopback.
    3. Write register 0x001F to 0x4000 to apply a software restart.

    Digital loopback is shallowest loopback path of the PHY. If it doesn't work, please check for other potential issues on your system (controller, timing, strap configuration ...)

    Regards,

    Hung Nguyen