Pcie device can not work

Autonomous Machines Jetson & Embedded Systems Jetson AGX Xavier
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1

I have made a custom carrier board for the Jetson AGX Xavier.This is my hardware design.

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When the board is powered up, it can’t find pcie device(FPGA,7K325T-xilinx) and there is no pex_clk_100m.
please help me!

3

Here is how it can be root-caused.

  • Remove “nvidia,enable-power-down” DT entry from the respective controller’s node. This ensures that the controller is not powered down when the PCIe link is not up. (FWIW, the default behavior is that the controller gets powered down when there is no PCIe link up. This means that the REFCLK is observed on the endpoint side for a brief period of time i.e. during link-up procedure)
  • At this stage, REFCLK is expected to come to EP after the boot. So, please check that whether the REFCLK is coming correctly or not. If there is no REFCLK, then, I’m afraid there is something fundamentally wrong with the routing of the REFCLK
  • After confirming that the REFCLK is flowing in to the EP, observe the PERST# toggles during enumeration. A 1-0-1 transition is expected on PERST#.
  • If both of the above are working fine, then, check the Tx/Rx routing. Tx from Tegra should go to Rx of the EP and Rx of Tegra should be connected to Tx of the EP.
4

Remove “nvidia,enable-power-down” DT entry from the respective controller’s node.

I can’t find where to remove “nvidia,enable-power-down”.

can you tell me where the DT file is?

5

Download the kernel source from l4t archive.

https://developer.nvidia.com/embedded/linux-tegra-archive
Follow below page to build dtbs.

https://docs.nvidia.com/jetson/l4t/index.html#page/Tegra%20Linux%20Driver%20Package%20Development%20Guide/kernel_custom.html#

6

I mean there is so much DT files, i want to know which file i should modify.

7

Turn on your AGX, type command dmesg, grep “dts” inside it and it will tell you the answer.

8

I find dts fils, but there is no “nvidia,enable-power-down”

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9

You need to trace down the code.

10

I have downloaded and compiled kernel driver code, then i find “tegra194-p2888-0001-p2822-0000-common.dtsi” file.
But i mean there is no “nvidia,enable-power-down” in this file.
Did i make something wrong?

11

You can study the device tree structure first. Your comment just revealed that you don’t know how device tree works…

13

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