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allen18's avatar
allen18
Icon for Occasional Contributor rankOccasional Contributor
1 year ago

Stratix10 PCIe clock structure issue

Hello everyone,

I am using quartus Pro 22.3 , device ( stratix10 1SX110HN2F43I2VG ) , IP core ( L-Tile and H-Tile Avalon Memory-mapped Intel FPGA IP for PCI Express 22.2.0, GEN 3X4 125Mhz.

ug_s10_pcie_avmm-683667-666643 shows that The Intel L-/H-Tile Avalon-MM for PCI Express IP supports the Separate Reference Clock With No Spread Spectrum architecture (SRNS), but not the Separate Reference Clock With Independent Spread Spectrum architecture (SRIS).

When I use the Common Clock Architecture (pcie reference clock come from the PC board through the Oculink interface), everything is normal and the example design can run successfully. But when I modify the pin constraints and use a 100M local clock from the FPGA board, Linux kernel will continue to print errors and the example design cannot run normally.

I don't think these clocks are spread spectrum clocks, what could be the possible reason for this ?

19 Replies

  • VenT_Altera's avatar
    VenT_Altera
    Icon for Frequent Contributor rankFrequent Contributor

    Hi allen18,


    Yes, Stratix 10 L-/H-Tile PCIe IP does not support SRIS, and the on-board oscillator is not used for PCIe.

    Please use the SRNS or Common Reference Clock with Spread Spectrum Clocking architecture instead.


    Additionally, please ensure both the RP and EP sides of the link disable the spread spectrum if using the separate clock architecture.


    KDB: https://www.intel.com/content/www/us/en/support/programmable/articles/000075574.html


    Thanks.

    Best Regards,

    Ven


    • allen18's avatar
      allen18
      Icon for Occasional Contributor rankOccasional Contributor

      Hi ventt,

      I think my current application scenario should be SRNS,why the on-board oscillator is not used for PCIe reference clock ?

  • VenT_Altera's avatar
    VenT_Altera
    Icon for Frequent Contributor rankFrequent Contributor

    Hi allen18,


    Thanks for reaching out.


    Allow me some time to investigate your issue. I shall come back to you with the findings.


    Thanks.

    Best Regards,

    Ven