ACPI BIOS Error (bug): Could not resolve symbol [\_SB.PCI0.GP17.VGA.LCD._BCM.AFN7]

Question

The fault:

ACPI: Video Device [VGA1] (multi-head: yes  rom: no  post: no)
ACPI BIOS Error (bug): Could not resolve symbol [\_SB.PCI0.GP17.VGA.LCD._BCM.AFN7], AE_NOT_FOUND (20190816/psargs-330)
Initialized Local Variables for Method [_BCM]:
Local0: 00000000ea353c08 <Obj>           Integer 00000000000000FF
Local1: 00000000418bc901 <Obj>           Integer 0000000000000000
Initialized Arguments for Method [_BCM]:  (1 arguments defined for method invocation)
Arg0:   00000000c180e4bd <Obj>           Integer 0000000000000064
ACPI Error: Aborting method \_SB.PCI0.GP17.VGA.LCD._BCM due to previous error (AE_NOT_FOUND) (20190816/psparse-531)
ACPI Error: Evaluating _BCM failed (20190816/video-357)

My System: ASRock B450 PRO4 Mainboard, AMD Ryzen 3 2200G, Ubuntu 18.04, Kernel 5.4.0-45-generic, amdgpu is loaded... Perhaps someone can help please.

lshw -c video
  *-display                 
       description: VGA compatible controller
       product: Raven Ridge [Radeon Vega Series / Radeon Vega Mobile Series]
       vendor: Advanced Micro Devices, Inc. [AMD/ATI]
       physical id: 0
       bus info: pci@0000:09:00.0
       version: c8
       width: 64 bits
       clock: 33MHz
       capabilities: pm pciexpress msi msix vga_controller bus_master cap_list rom
       configuration: driver=amdgpu latency=0
       resources: irq:63 memory:c0000000-cfffffff memory:d0000000-d01fffff ioport:f000(size=256) memory:fce00000-fce7ffff memory:c0000-dffff

Solution

The ACPI driver attempted to evaluate (execute) the ACPI brightness control method for the screen but this failed because the ACPI AML byte code in your firmware did not have the object _SB.PCI0.GP17.VGA.LCD._BCM.AFN7 defined for some reason. The upshot of all of this is that the ACPI brightness control won't work. This is a firmware issue, I do not know of any workarounds apart from checking to see if you can get an updated BIOS firmware that may fix this.

Comments

[Boris Hamanov]

Show me sudo dmidecode -s bios-version. Start comments to me with @heynnema or I'll miss them.

[Christian Völkel]

@heynnema - sudo dmidecode -s bios-version - P4.20

[Christian Völkel]

I have already the newest BIOS Version P4.20 installed... So should I go back to Version 3.50 ???

[Christian Völkel]

sudo dmidecode -s bios-version P4.20

[Boris Hamanov]

@ChristianVölkel I'd recommend talking with the ASRock Support folks, and ask them why newer versions of the BIOS aren't recommended for Raven processors. Then you'll know what to do. Report back.

[Boris Hamanov]

@ChristianVölkel Status please...