https://bugs.freedesktop.org/show_bug.cgi?id=109375
--- Comment #1 from Rafał Miłecki zajec5@gmail.com --- For a comparison: behavior with the commit 262485a50fd4~1 (before the regression):
Before suspend:
cat /sys/class/backlight/amdgpu_bl0/{actual_brightness,brightness}
255 255
After resume:
cat /sys/class/backlight/amdgpu_bl0/{actual_brightness,brightness}
250 255
Looks like a problem with amdgpu restoring backlight after resume.