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Linux/TMDXIDK5718: Cannot find PCIe EP device on host

Prodigy 70 points

Replies: 13

Views: 312

Part Number: TMDXIDK5718

Tool/software: Linux

Hello,

This is a question about the PCIe endpoint on TMDXIDK5728 board but the forum doesn't have it as part number so I set TMDXIDK5718.

I'm using the PCIe endpoint in enpoint mode and want to test with the Linux endpoint framework driver. To use the PCIe endpoint in endpoint mode I followed the docs and made a modified PCIe cable:

http://software-dl.ti.com/processor-sdk-linux/esd/docs/latest/linux/Foundational_Components_Kernel_Drivers.html#pcie-end-point

http://processors.wiki.ti.com/index.php/PCIe_CableMod

I connected the board with a Linux PC via the modified PCIe cable, followed the instructions in the doc, and then rebooted the PC, but there's no new PCIe device found (lspci shows no new device). On the board Linux system when I bind the endpoint function driver to endpoint controller driver there're warnings about BAR4/5 not successfully set, but it's expected because there're only 4 inbound windows according to the device tree file. No other warnings/errors shown.

What could be the problem? Is this feature only for two same board connecting each other, not for PC with the board? Or maybe it's the modified cable issue? I cannot get the exactly same cable as the wiki, so I bought a PCIe 1x male-to-male cable, and removed all 12V, 3.3V, clk+/- pins on one side.

Thanks!

  • In reply to Rex Chang:

    Hi Rex,

    I see you mentioned this in both threads:

    "the EP should take clock from RC. So, the PCIE_SS shouldn't use current internal clock source, but take the external clock from RC through LJCB_CLKP/N by programming ACSPCIE in RX mode.

    Please refer to section 26.4 PCIe PHY Subsystem of the AM5728 TRM, SPRUHZ6J, and take a look at Figure 26-17."

    If the another TMDXIDK5728 plays the RC role, this is not needed as the EP using the internal clock which is same as the RC clock?

    Xin

  • In reply to zhangxin:

    Hi, Xin,

    That is correct. When both RC and EP are TI AM57x  EVMs, each can run its internal clock and they are in sync.

    Rex

     

  • Hi,

    To who finds this thread for the same question, despite the clock/power is disconnected on the cable, my colleague swapped Tx and Rx of the cable then the board as RC can find the board as EP connected.

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