PCIe troubleshooting grid

Applicable for

STM32MP25x lines

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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>; 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.

Peripheral Component Interconnect express

General-purpose input/output (A realization of open ended transmission between devices on an embedded level. These pins available on a processor can be programmed to be used to either accept input or provide output to external devices depending on user desires and applications requirements.)