Comment # 18 on bug 1186896 from P

I have tried 5.13.rc7 from Kernel:HEAD:Backport and 5.12.12 from
Kernel:stable:Backport.
They both yield the same outcome:

| Options                      | boot | brightness | Comments                  
                           |
| ---------------------------- | ---- | ---------- |
----------------------------------------------------- |
| -                            | No    | No          | Hangs at "fb0: switching
to amdgpudrmfb from EFI VGA" |
| acpi=off                     | Yes    | Yes          | No ACPI functionality 
                               |
| nomodeset                    | Yes    | No          | Hangs at "fb0:
switching to amdgpudrmfb from EFI VGA" |
| amdgpu.backlight=0           | No    | No          |                         
                             |
| nomodeset���amdgpu.backlight=0 | Yes    | No          |                        
                              |