** Changed in: linux (Ubuntu)
       Status: New => Confirmed

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https://bugs.launchpad.net/bugs/2099935

Title:
  PCI initialization failure following kernel panic reboot on Raspberry
  Pi CM4

Status in linux package in Ubuntu:
  Confirmed

Bug description:
  Ubuntu Server 24.10 
  Linux ubuntu 6.11.0-1004-raspi #4-Ubuntu SMP PREEMPT_DYNAMIC Fri Sep 27 
22:25:34 UTC 2024 aarch64 aarch64 aarch64 GNU/Linux

  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 properly.
  •     When this happens:
  o     The Wi-Fi card is not recognized.
  o     The lspci command shows no PCI devices.
  o     The dmesg log includes the message:

  [    0.591441] brcm-pcie fd500000.pcie: link down

  •     A soft reboot does not fix the issue.
  •     The only way to recover is to completely remove and reconnect power 
(hard reboot).

  
  We have tried modifying /boot/firmware/config.txt and 
/boot/firmware/cmdline.txt, which has reduced but not fully resolved the issue.

  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

  
  The same issue does not occur on Raspberry Pi OS - it seems to be specific to 
Ubuntu.

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

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