amdgpu: Brightness is not restored across reboots.

[Mershl]

systemd version the issue has been seen with

systemd-245.7

Used distribution

Fedora 32

Expected behaviour you didn't see

Brightness is restored across boots

Unexpected behaviour you saw

Brightness is set to max after reboot

Steps to reproduce the problem

• Decrease brightness.
• Reboot.
• systemd-backlight@backlight:amdgpu_bl0.service will show:
  amdgpu_bl0: Saved brightness 7628 too high; decreasing to 255.
• The issue can be reproduced with wayland and x11.

System information

System:
  Kernel: 5.7.14-200.fc32.x86_64 x86_64 bits: 64 Desktop: Gnome 3.36.4 
  Distro: Fedora release 32 (Thirty Two) 
Machine:
  Type: Laptop System: LENOVO product: 20NKS01Y00 v: ThinkPad T495 
  serial: <filter> 
  Mobo: LENOVO model: 20NKS01Y00 serial: <filter> UEFI: LENOVO 
  v: R12ET51W(1.21 ) date: 04/20/2020
Graphics:
  Device-1: AMD Picasso driver: amdgpu v: kernel 
  Display: x11 server: Fedora Project X.org 1.20.8 driver: amdgpu,ati 
  unloaded: fbdev,modesetting,vesa resolution: 1920x1080~60Hz 
  OpenGL: 
  renderer: AMD RAVEN (DRM 3.37.0 5.7.14-200.fc32.x86_64 LLVM 10.0.0) 
  v: 4.6 Mesa 20.1.5 

Xorg errors (grep '^[.*(EE)' /var/log/Xorg.0.log ~/.local/share/xorg/Xorg.0.log | cut -d ':' -f 2- )

     [    16.425] (EE) open /dev/fb0: Permission denied

Kernel arguments

rhgb quiet

[yuwata]

Duplicate of #16630 and #16600.