** Platform Info **
Distribution: Leap 15.2
Kernel: 5.3.18-lp152.75-default
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]

Symptom:
Changing the brightness of the laptop screen doesn't work. Turning the scroll
wheel over de battery icon in the system tray does't do anything. No change in
brightness. But I do get the mmediate and unexplainable popup of the external
monitor widget (see attachment).

Peculiarly, the settings are correctly registered.

Before:
rietgors:/sys/devices/pci0000:00/0000:00:08.1/0000:05:00.0/backlight/acpi_video0
# cat actual_brightness max_brightness
21
49

After:
rietgors:/sys/devices/pci0000:00/0000:00:08.1/0000:05:00.0/backlight/acpi_video0
# cat actual_brightness max_brightness
36
49

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

Some information you might find useful:

xlgears: Accellaratioin seems to work normally. xlgears gives me > 3200 fps.

xgamma: value changes are properly registered:
koos@rietgors:~> xgamma -rgamma 0.2 -ggamma 0.4 -bgamma 0.6
-> Red  1.000, Green  1.000, Blue  1.000
<- Red  0.200, Green  0.400, Blue  0.600

However no change in color whatsoever.


xbacklight: Doesn't work.
koos@rietgors:~> xbacklight -get
No outputs have backlight property

Next to the default Leap 15.2 kernel, I've tried the following kernels:
- kernel-default-5.13.rc3/rc4 from KOTD
- kernel-default-5.12.9 from the Kernel Stable repo

However those kernels don't work at all. They hang hard during the boot
process. If I select the Fail Safe option from the boot menu, they both hang at
the following location in the boot screen (typed over from photo, see
attachment):
    [drm] amdgpu kernel modesetting enabled.
    Virtual CRAT table created for CPU
    amdgpu: Topology: Add CPU node
    fb0: switching to amdgpudrmfb from EFI VGA