Compute Module • PCI initialization failure following kernel panic reboot on Raspberry Pi CM4

Linux version 6.6.51+rpt-rpi-v8 (serge@raspberrypi.com) (gcc-12 (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40) #1 SMP PREEMPT Debian 1:6.6.51-1+rpt3 (2024-10-08)

We're seeing that following a kernel panic and reboot, the PCI fails to initialize correctly and associated devices (such as Wi-Fi card) are not available.

Issue Description:
- On the first boot, everything works correctly.
- However, after a Kernel Panic, the device reboots, but PCIe does not reset or re-initialize reliably
- When this happens:
- The Wi-Fi card is not recognized.
- The command shows no PCI devices.
- The log includes the message
- A soft reboot does not fix the issue.
- The only way to recover is to completely remove and reconnect power (hard reboot).

The problem occurs about 50% of the time.

How to Reproduce the Problem:
1. Power up the hardware
2. Run ‘lspci’ – observe the result includes the PCI Bridge and Wi-Fi card
3. Trigger a kernel panic with the command ‘echo c | sudo tee /proc/sysrq-trigger’, causing a reboot
4. Run ‘lspci’ – observer the output is now empty

Any assistance/guidance on how to troubleshoot this would be much appreciated!

Statistics: Posted by EpitiroDeveloper — Thu Mar 06, 2025 6:32 pm — Replies 4 — Views 95

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