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TMS320DM8168: Ask about the problem that DM8168 can't find PCIE devices

Part Number: TMS320DM8168


【problem description】: DM8168 has only one PCIE device FPGA outside, and FPGA can be loaded normally

1. after power up, DM8168 PCIE can't find device FPGA. The measurement signal finds that DM8168 sends out PCIE differential signal, but it doesn't send out signal after a period of time. After that, there is no signal and will not initiate the building chain signal.

2.DM8168 TX difference pair is connected to the ground resistance to the ground, and the DM8168 will continuously send out the detection of the chain signal and will not be interrupted.

3. by querying the state of the FPGA related PCIE register, the current state is in the Polling.Active state, and the FPGA is constantly sending out PCIE differential signals

【help】:

1.When DM8168 detects the PCIE device and sends the chain signal, under what conditions can it no longer send PCIE signal, and it will not redetect the building chain, and how to restart the chain by way of any other way.

2.DM8168 sends out the chain signal and breaks it. After querying DM8168, which registers can determine the current state of DM8168 PCIE module, or by any way, we can know the current PCIE scanning error.

  • Hi Sean,

    Do you use DM816x TI EVM or custom board?

    Do you use DM816x EZSDK 5.05.02.00?

    Regards,
    Pavel
  • Hi Pavel
    Thank you for the reply
    It is custom board that is developed by ourselves.Not DM8168 TI EVM,But what is the problem that the version of what you say can solve?about PCIE?
  • Sean wang said:
    1.When DM8168 detects the PCIE device and sends the chain signal, under what conditions can it no longer send PCIE signal, and it will not redetect the building chain, and how to restart the chain by way of any other way.

    DM816x PCIe module functionality is documented in DM816x TRM, ch 17. I made a search but I was not able to find such terms as "chain",  "chain signal" and "building chain". Please refer to this TRM chapter for better understanding of PCIe module functionality.

    Sean wang said:
    2.DM8168 sends out the chain signal and breaks it. After querying DM8168, which registers can determine the current state of DM8168 PCIE module, or by any way, we can know the current PCIE scanning error.

    The DM816x PCIe module state status registers are : DEBUG0, DEBUG1, PM_CTL_STAT and PL_FORCE_LINK. For more details check TRM section:

    17.4.3 Encoding of LTSSM State in DEBUG Registers

    There is also PCIESS Interrupt events which signals errors, see section 17.2.9.1 Interrupt Events and Requests

    See also below wiki page:

    Regards,
    Pavel

  • Sean wang said:
    It is custom board that is developed by ourselves.Not DM8168 TI EVM

    Try to reproduce this issue on DM816x TI EVM, thus you can isolate if the issue is HW or SW.

    Sean wang said:
    But what is the problem that the version of what you say can solve?about PCIE?

    The latest SW version has all the PCIe related patches integrated.

    Regards,
    Pavel