Last edited 3 weeks ago

PCIe troubleshooting grid

Applicable for STM32MP25x lines

Some typical issues related to the PCIe feature are listed below. Solutions or debugging methods are proposed for these issues.

If your issue is not listed, try also looking in the articles in the Category:PCIe or troubleshooting grids categories.


Symptom Resolution
lspci does not show the device, device not enumerated. A possible issue is that the common reference clock is not started, check that the clkreq# sideband signal correctly toggles to low.

If it remains high, which indicates a nonconformant connection, force the GPIO to low in the device tree pcie_rc node:

&pcie_rc { 
-       pinctrl-names = "default", "init", "sleep"; 
-       pinctrl-0 = <&pcie_pins_a>; 
-       pinctrl-1 = <&pcie_init_pins_a>; 
-       pinctrl-2 = <&pcie_sleep_pins_a>; 
+       pinctrl-names = "default", "sleep"; 
+       pinctrl-0 = <&pcie_init_pins_a>; 
+       pinctrl-1 = <&pcie_sleep_pins_a>;  
Info white.png Information
By forcing the clkreq# to low, the host PCIe controller will not be able to enter in the low power L1.1 substate if ASPM powersafe mode is enabled.