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C6678 PCIE link is broken when pc Restart

Henry Zhang101212
Prodigy 120 points


Now My C6678 is configured as EP,PC is RC. when pc is restarted ,the pcie link of 6678 will be Disconnected.

Someone says that because that pc send hot reset to pciess of C6678,So my question is how can I know pciess is disconnected.

 

  • 0
    TI__Genius 12065 points

    Henry,

    You can monitor the LTSSM_STATE field (bits[4:0]) in DEBUG0 register (0x21801728) to see the status of the PCIe link. It will not be 0x11 if the link is disconnected.

    Please see the details we discussed in the following thread:

    http://e2e.ti.com/support/dsp/c6000_multi-core_dsps/f/639/p/236704/829673.aspx#829673

  • 0 in reply to Steven Ji
    Prodigy 120 points

    YES,The LTSSM_STATE is changed to 0x00,and link_trainning_en bit is set to 0.

    I 'm wondering why.

    now I change the link_training_en to 1 in order to make 6678 to begin link training ,the PC will go into stuck and it can not be in normal unless ipower down it for restart.

    what's more ,the corepacs is also hung.

    the problem is that the LTSSM had been changed to 0x00 ,and link training is disabled.the most terrible thing is that link traing can not be enabled again.

  • 0 in reply to Henry Zhang101212
    TI__Genius 12065 points

    Henry,

    Either the DSP or the host PC receives reset, the PCIe link will be down and the PCIe module needs to re-initialized to get the link up (re-train the link).

    The PCIe boot code (EVM set in PCIe boot mode) usually initializes the PCIe module. I guess when you reset the host PC machine, the DSP EVM does not get reset and the ROM boot process does not be re-initialized (PCIe boot code does not be re-run).

    Could you please try to reset the EVM along with the host machine and let PCIe boot code to re-initialize the PCIe module, just like what happens in the power-on reset please?

    Or for some reasons, you do not want to reset DSP when you reset the PC host, could you please try to power down the PCIe module in the PLL configuration and re-enable it again which will put the PCIe registers into default status and then retrain the link (set LTSSM_EN bit) before you reset the PC host please?

    And please make sure the PC host will re-train the PCIe link as well after the hot reset, since both peers over the PCIe link need to be prepared for the link up.