After moving to BSP 7.1.0, I encountered PCIe link issues with at least the Qualcomm QCA6698AQ chipset. The device simply won’t show up under lspci in most cases.
I haven’t tried other devices, but I think it happens after link training wants to go to higher speeds than Gen1.
I found it to be related to this particular change in the device tree that removes the limitation to Gen1 speeds.
In theory, this change should not create issues, but reverting that particular commit in our DT solved it nonetheless.
We are using a custom board with PCIe switches, so of course this may also be a hardware issue on our end, but the switches are supporting up to Gen 3.
Just wanted to leave this here in case someone else also gets this issue after moving to BSP 7.1.0.
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Hello Patrik,
Thank you for sharing your experience with the PCIe link issues on the Apalis iMX8QM module after upgrading to BSP 7.1.0. It seems the problem is linked to a device tree change that removed the Gen1 speed limitation, affecting the link training process with the Qualcomm QCA6698AQ chipset.
Here are some steps you might consider to address this issue:
Device Tree Adjustment: Since reverting the device tree change resolved the issue, you might want to continue using this modification if Gen1 speeds are adequate for your application. This involves explicitly setting the PCIe link speed to Gen1 in the device tree.
Hardware Verification: While your custom board and PCIe switches support up to Gen3, it’s worth ensuring there are no compatibility issues or signal integrity problems at higher speeds. Reviewing the hardware design and signal quality on the PCIe lanes could be beneficial.
Testing with Other Devices: If feasible, try connecting other PCIe devices to see if the issue is specific to the Qualcomm chipset or if it affects other devices as well.
Kernel and Driver Logs: Check the kernel logs (dmesg) and PCIe driver logs for any error messages or warnings during the PCIe link training process. These logs can provide valuable insights into the issue.
Consult SoC and Module Errata: Reviewing any errata documents for the Apalis iMX8QM module and the i.MX8 SoC might reveal known PCIe issues that could be relevant.
By following these steps, you can better determine whether the issue stems from software changes in BSP 7.1.0 or a hardware-related problem on your custom board. If Gen1 speeds are sufficient for your needs, maintaining the device tree modification could be a practical solution.
I hope this helps, and thank you again for sharing your findings.
Best regards,
Toradex AI Assistant
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