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sureshreddy's avatar
sureshreddy
Icon for New Contributor rankNew Contributor
5 years ago

Issue with TSE MAC of cyclone IV FPGA when connect phy is moved into/out of isolate mode

we have a product where in TSE MAC of cyclone 4 FPGA is connected to spear1380 through PCIe interface. Phy connected to MAC is DP83640 . vxWorks is running on the spear1380 processor. When phy is taken into/out of isolate mode, the ethernet communication seems to be delayed/taking longer time, because of which other tasks having lower priority than ethernet and are getting more delayed and system behaviour is changing. any one please comment on if the behaviour of tse mac in fpga will change if phy connected to it goes into isolated mode.

4 Replies

  • Deshi_Intel's avatar
    Deshi_Intel
    Icon for Regular Contributor rankRegular Contributor
    5 years ago

    Hi,


    Can you elaborate more about "isolation mode" that you mentioned in below statement ?

    • if the behaviour of tse mac in fpga will change if phy connected to it goes into isolated mode
    • If you are referring to cable unplug situation then Ethernet link down is expected behaviour


    TSE MAC just handle Ethernet PHY and LINK layer communication only while you seems to be talking more about transition and handshaking issue at higher layer protocol like software control in Operating System ?


    Thanks.


    Regards,

    dlim


    • sureshreddy's avatar
      sureshreddy
      Icon for New Contributor rankNew Contributor
      5 years ago

      Hi,

      Following is the clipping from datasheet.

      "In Isolate Mode, the DP83640 does not respond to packet data present at TXD[3:0] and TX_EN inputs and presents a high impedance on the TX_CLK, RX_CLK, RX_DV, RX_ER, RXD[3:0], COL, and CRS/CRS_DV outputs. When in Isolate Mode, the DP83640 will continue to respond to all serial management transactions over the MII.
      While in Isolate Mode, the PMD output pair will not transmit packet data but will continue to source 100BASE-TX scrambled idles or 10BASE-T normal link pulses"

      In summary, in this mode, the link will be up and rx and tx transactions does not happen. There is requirement in our application where we have to go into and come out of isolate mode.

      When software moves phy into this mode and come out, the behavior of the network task is changing. Seems to be there is a more delay in processing the packets received through PCIe interface

  • Deshi_Intel's avatar
    Deshi_Intel
    Icon for Regular Contributor rankRegular Contributor
    5 years ago

    HI,


    Looks like Isolate Mode is unique feature for the DP83640 external PHY.


    Do you know how does it provide the handshake/feedback back to TSE MAC or your high level application software when entering "isolated mode" ?


    I can then cross check how TSE will respond to this certain "triggering signal/status" behaviour accordingly


    Thanks.


    Regards,

    dlim


  • Deshi_Intel's avatar
    Deshi_Intel
    Icon for Regular Contributor rankRegular Contributor
    5 years ago

    Hi,


    I have not hear back from you for some time.


    Hopefully you are making progress in your debug.


    I am now setting this case to closure. Feel free to post new forum thread if you still have enquiry in future.


    Thanks.


    Regards,

    dlim