Comment # 20 on bug 1180749 from Takashi Iwai

Thanks.  Then I misunderstood situation as if the backlight control didn't take
any effect.

Now I refreshed the OBS KMP repo to contain the possible fix.  It's being
rebuilt, and please give it a try later.  The rpm changelog should contain the
entry like:
- Add a proper fix (attempt):
  0001-drm-amd-display-Fix-the-brightness-read-via-aux.patch

At first, uninstall the previous KMP, just do "zypper rm
amdgpu-dbg-kmp-default"
Then re-install the new rpm, run mkinitrd and retest.  This doesn't contain the
debug prints, so report back whether it works or not.