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AMD Ryzen 7 4700H Renoir: brightness + external screen do not work

Background

I'm running into a kernel problem on openSUSE. After investigation and various tests, the openSUSE kernel maintainer determined it's an upstream kernel issue, which I should report upstream. I believe this repo should be the correct starting point for my bug report. Please correct me if this is not the case.

The original bug report can be found here: https://bugzilla.opensuse.org/show_bug.cgi?id=1186896

Bug Summary

I don't have brightness control or an external screen, unless I disable acpi. If I disable acpi (kernel boot option acpi=off) than I do have brightness control, and the external screen works too. But obviously I then don't have any acpi functionality (single core, Fn keys, etc)

Laptop Details

Laptop: Clevo NL51RU

BIOS: insyde 1.07.05

Distribution: openSUSE Leap 15.2/15.3 + Tumbleweed

Recent kernels tried (from the openSUSE repos):

  • kernel-default-5.12.12
  • kernel-default-5.13.rc7

CPU: Rhyzen 7 4700U

Graphics:

# lspci -nnk | grep -A3 VGA
05:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Renoir [1002:1636] (rev c2)
        Subsystem: CLEVO/KAPOK Computer Device [1558:a500]

Detailed symptoms:

Boot option Boots? Brightness? Notes
- No - Hangs at switching to amdgpudrmfb from EFI VGA [*]
nomodeset Yes No Any attempt to set the brightness results in the external monitor widget to popup
amdgpu.backlight=0 No - Hangs at switching to amdgpudrmfb from EFI VGA [*]
amdgpu.backlight=0 nomodeset Yes No
acpi=off Yes Yes No acpi functionality

For those two scenarios above where the laptop boots fine, but without brightness control, there is this funny additional symptom: Turning the scroll wheel over de battery icon in the system tray doesn't do anything. No change in brightness. But I do get the immediate and unexplainable popup of the external monitor widget (see attachment).

Peculiarly, the settings are correctly registered.

rietgors:# cd /sys/devices/pci0000:00/0000:00:08.1/0000:05:00.0/backlight/acpi_video0

Before:

rietgors:# cat actual_brightness max_brightness
21
49

After:

rietgors:# cat actual_brightness max_brightness
36
49

Oddly, the max_brightness value is now 49. But in the scenario where I do have brightness control (acpi=off), the max_brightness value is 255.

Exactly the same happens when I directly echo values in the "brightness" device from the command line. No change in brightness but an immediate popup of the external monitor widget.

[*] For ease of reference: these are the last 4 lines from the boot log if the laptop hangs:

[drm] amdgpu kernel modesetting enabled.
Virtual CRAT table created for CPU
amdgpu: Topology: Add CPU node
fb0: switching to amdgpudrmfb from EFI VGA

Please be aware: I think I'm computer savvy, but working with or on the kernel is way out of my comfort zone. I'd be happy to investigate and try further. But I probably will need detailed instructions.