AMDGPU Hangs During Reboot/Shutdown on CachyOS

Issues & Assistance
1

Hello everyone,

I have the following problem with a freshly installed CachyOS version

System Overview

  • GPU: AMD Radeon RX 7900 XTX

  • CPU: AMD Ryzen 5800x3d

  • Motherboard Aorus B550 Elite V2

  • Monitor: 4K 240 Hz connected via DisplayPort 2.1

  • Operating System: CachyOS (tested with linux-cachyos 6.17.1-2 and linux-lts 6.12.51-1)

  • Bootloader: systemd-boot

  • Desktop Environment: KDE Plasma (Wayland)

The system runs perfectly under load —, 4K/240 Hz, HDR — everything is stable.
However, reboot and shutdown hang for 1–2 minutes before the system finally powers off or restarts.

The only command that reboots instantly is:

sudo systemctl reboot --force --force

Normal sudo reboot or poweroff will always hang.

(journalctl -b -1)

During the failed shutdown/reboot, the kernel repeatedly logs AMDGPU timeouts such as:

amdgpu 0000:07:00.0: [drm] REG_WAIT timeout 1us * 100000 tries - optc1_wait_for_state line:840
amdgpu 0000:07:00.0: [drm] REG_WAIT timeout 1us * 10 tries - optc3_lock line:130
amdgpu 0000:07:00.0: [drm] REG_WAIT timeout 1us * 100 tries - dcn32_program_compbuf_size line:139

What i have tried

  1. Different Kernels:

    • linux-cachyos (6.17.1-2)

    • linux-cachyos-rc

    • linux-lts (6.12.51-1)
      → Issue persists across all kernels.

  2. Kernel Parameters Tested:

    amdgpu.runpm=0
amdgpu.aspm=0
amdgpu.dc=1
reboot=efi
snd_hda_intel.dmic_detect=0

    → No effect on the hang.

  3. BIOS Settings Changed:

    • “AC Back” → Off

    • “PCIe ASPM Mode” → Disabled

    • “ErP Ready” → Enabled
      → None of these fixed the problem.

  4. Renamed /usr/lib/udev/rules.d/50-sata.rules to avoid LPM warnings → no difference.

  5. HDR toggled on/off → no effect.

would be grateful for any help or advice.

Thanks

2

hello check if somes serices are unmount, because, if one stay before shutdwon, it will hang. Could you check.

5may be disk, or network or else ?)

3

Thanks for the info, which command do I use to check this?

4

I try everything , different distros , but no one is working , with dp 2.1 , 240hz. Everytime reboot stuck for 2 mins, on gnome i can not set 240hz (after this i get Black screen)

On cachyos everytime i get amdgpu REG_Wait timeout , so i must go back to Winshit , thanks

amdgpu 0000:07:00.0: [drm] REG_WAIT timeout 1us * 100000 tries - optc1_wait_for_state line:840
amdgpu 0000:07:00.0: [drm] REG_WAIT timeout 1us * 100 tries - dcn32_program_compbuf_size line:139
amdgpu 0000:07:00.0: [drm] REG_WAIT timeout 1us * 100000 tries - mpc2_assert_idle_mpcc line:483