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AM335x Gigabit ethernet configuration and testing

nagendra bankupalli
Intellectual 360 points
Other Parts Discussed in Thread: AM3352

Hello TI,

we are using AM3352 for one of out projects..the AM335x is connected with through RGMII interface with marwell switch (Gbit) with out PHY... (RGMII <---> RGMII)  and the system is working fine... at 100 Mbps

but the am335x is not working at Gigabit speed 

we are using "u-boot-2013.01.01-psp05.07.00.00"  and kernel linux-3.2.0-psp04.06.00.10

can you please explain how to enable Gbit Ethernet for AM335x in u-boot and in kernel and how to test the speed?

regards

Nagendra

  • 0
    TI__Guru**** 393215 points
    Hi Nagendra,
     
    Are you aware of Errata Advisory 1.0.10? This will affect AM335X silicon Rev.1.0. I suppose your Marvell switch supports PHY mode on the EMAC connected to the AM335X?
  • 0 in reply to Biser Gatchev-XID
    Intellectual 360 points

    yes! 

    i remember that we can not use RGMII to RGMII for AM335x

    we have connected RGMII <---> RGMII with marvell and added dummy phy driver to make it work, and it is working fine

    The Marvell switch is Gigabit speed, so i would like to know how to enable Gbit speed on AM335x?

    with out PHY am335x will not work at gigabit speed ?

    can you please elaborate your answer and also correct me if i am wrong

    if AM335x will not support RGMII  to RGMII  how it is working with marvell at 100 Mbps speed with out fail ?

    please help us , since this is very critical 

    thanks and regards

    Nagendra

  • 0 in reply to nagendra bankupalli
    TI__Guru 63145 points

    What do you mean you added a PHY driver?

    100Mbps operates RGMII at a much slower clock rate that 1000Mbps.

    You need to make sure the RGMII signal traces on the PCB or attached RGMII device provides a 1.8ns +/- 300ps delay on the transmit and receive clocks relative to their respective data paths since AM335x does not support internal delay mode.  Have you performed a timing analysis for the RGMII signals taking into account timing parameters of both devices?

    The AM35x MAC was only designed to be attached to a RGMII PHY and when connected to another RGMII device it is expected to operate as an RGMII PHY.  Some Ethernet switches have at least one port that can be configured to operate in PHY mode.  Can your Ethernet switch operate in PHY mode?

    The RGMII specification defines an optional in-band status feature and the AM335x MAC expects the attached Ethernet PHY to provide this function.  Does your Ethernet switch support in-band status?

    Regards,
    Paul