IMX8M Mini PCIe PLL PLL lock failure

[pikorn]

I am using an IMX8MM on a custom board design and have an issue with PCIe PLL lock using an external clock source.

[    2.532274] imx6q-pcie 33800000.pcie: EXT REF_CLK is used!.
[    2.538174] imx6q-pcie 33800000.pcie: GPR15=6188ffff
[    2.564533] imx6q-pcie 33800000.pcie: PCIe PLL lock timeout

I understand from other similar posts that we may have an issue with our external clock getting to the IMX8 and we are actively investigating this. However, I noticed that when that when the PLL lock fails the boot hangs shortly after. When I disable the pcie0 node in the device tree then the boot is successful.

Is it typical for the IMX8 to appear to "hang" after PCIe PLL lock failure? Can this hang be caused by a poor PCIE CLK signal?

Thank you for the assistance,
Matt

[AldoG]

Hello,

Yes it is possible to cause a hang as you have seen from other threads, so yes you should look into the PCIe CLK signal.

Also, I think this should be a good reference:

https://community.nxp.com/t5/i-MX-Processors/iMX8M-Mini-Use-PI6CFGL201BZDIEX-as-PCIe-REF-CLK/m-p/129...
https://community.nxp.com/t5/i-MX-Processors/iMX8M-Mini-CLK-Generator-Clocking-Issue/m-p/1258056

Best regards,
Aldo.