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66AK2G12: EVMK2G can not detect PCIe card installed after Linux kernel runs?

Tom Chen
Prodigy 150 points
Part Number: 66AK2G12

Hello,

I have a TI EVMK2G board, I installed a PCIe card to the PCIe 1x connector after Linux kernel login prompt is shown. I login and run lspci, I am surprised to see that EVMK2G can not detect this board even after a long time! lspci only shows k2g's own PCIe module. So, it looks like K2G processor is not PCIe Plug & Play. However, if the card already installed before the EVMK2G board power on, then lspci can correctly display this device.

It is likely that K2G has a PCIe detection time window upon bootup. If the card is installed after the window, then the card can never be detected.

To resolve this issue, I am wondering if there is a way to restart K2G PCIe module or service or something similar, that is to force K2G PCIe module re-run link training after Linux kernel ready?

Tom

  • 0 in reply to Bin Liu
    Prodigy 150 points

    Yes, it is same issue. But I think it might be good to put in a separate thread as this happens on Ti board not on our customized board which has different design & timing.

    The key observation of these two threads is that, Ti K2G seems to have a PCIe discovery window, if the window is missed, for example, if the external PCIe card is not ready yet before the window expires, it can never be detected by K2G. This might be the reason why once a card is installed on 1x connector of EVMK2G, a warm reboot is always triggered - this might imply Ti K2G can only reliably detect PCIe devices during boot up time and external PCIe card is already installed, we do not see this on PC motherboard.

    Once EVMK2G failed to detect PCIe card, is it possible to "wake" up K2G PCIe module by changing its register value or toggling pins of 1x PCIe connector? I can see wave form from PCIe card on K2G's SOC_PCIE_RXN0, RXP0 pins, probably these signals are broadcasting its presence, but K2G has no reaction to it.

    Tom

  • 0 in reply to Bin Liu
    Prodigy 150 points

    Once PCIe card is detected, if I remove the card from 1x connector, lspci still shows the card.... The EVMK2G board seems to have serious PCIe detection issue:

    1. It does not always detect a card installed on the 1x connector after Linux kernel is running

    2. It can not detect a card removed from the 1x connector.

    Tom