Article 5P3EW Laptop backlight dims to zero on boot with kernel 5.14.0

Laptop backlight dims to zero on boot with kernel 5.14.0

by
Daedra
from LinuxQuestions.org on (#5P3EW)
I am going to assume this is some how caused by kernel 5.14.0 since the problem only started occurring after that upgrade. The laptop I have is an nvidia/AMD vega graphics hybrid, the problem is during boot once amdgpudrmfb takes over the backlight of the laptop drops to 0 and is barely visible. As a workaround for now I added this to rc.local

Code:echo 255 > /sys/class/backlight/amdgpu_bl0/brightnessThis will bring the backlight back up to max, but this was not necessary before 5.14.0. Any ideas on how to fix this are appreciated. Here is some dmesg output. I didn't find anything useful in it though
Code:[ 6.324280] [drm] amdgpu kernel modesetting enabled.
[ 6.330234] amdgpu: Virtual CRAT table created for CPU
[ 6.331078] amdgpu: Topology: Add CPU node
[ 6.331926] fb0: switching to amdgpudrmfb from EFI VGA
[ 6.332815] amdgpu 0000:06:00.0: vgaarb: deactivate vga console
[ 6.332839] amdgpu 0000:06:00.0: enabling device (0006 -> 0007)
[ 6.332884] amdgpu 0000:06:00.0: amdgpu: Trusted Memory Zone (TMZ) feature enabled
[ 6.334177] amdgpu 0000:06:00.0: amdgpu: Fetched VBIOS from VFCT
[ 6.334180] amdgpu: ATOM BIOS: 113-RENOIR-026
[ 6.334623] amdgpu 0000:06:00.0: amdgpu: VRAM: 512M 0x000000F400000000 - 0x000000F41FFFFFFF (512M used)
[ 6.334626] amdgpu 0000:06:00.0: amdgpu: GART: 1024M 0x0000000000000000 - 0x000000003FFFFFFF
[ 6.334628] amdgpu 0000:06:00.0: amdgpu: AGP: 267419648M 0x000000F800000000 - 0x0000FFFFFFFFFFFF
[ 6.334670] [drm] amdgpu: 512M of VRAM memory ready
[ 6.334672] [drm] amdgpu: 3072M of GTT memory ready.
[ 6.335443] amdgpu 0000:06:00.0: amdgpu: PSP runtime database doesn't exist
[ 7.040261] amdgpu 0000:06:00.0: amdgpu: RAS: optional ras ta ucode is not available
[ 7.047797] amdgpu 0000:06:00.0: amdgpu: RAP: optional rap ta ucode is not available
[ 7.047808] amdgpu 0000:06:00.0: amdgpu: SECUREDISPLAY: securedisplay ta ucode is not available
[ 7.048940] amdgpu 0000:06:00.0: amdgpu: SMU is initialized successfully!
[ 7.159638] kfd kfd: amdgpu: Allocated 3969056 bytes on gart
[ 7.173434] amdgpu: HMM registered 512MB device memory
[ 7.173493] amdgpu: SRAT table not found
[ 7.173498] amdgpu: Virtual CRAT table created for GPU
[ 7.173819] amdgpu: Topology: Add dGPU node [0x1636:0x1002]
[ 7.173834] kfd kfd: amdgpu: added device 1002:1636
[ 7.173845] amdgpu 0000:06:00.0: amdgpu: SE 1, SH per SE 2, CU per SH 18, active_cu_number 26
[ 7.176896] fbcon: amdgpu (fb0) is primary device
[ 7.218403] amdgpu 0000:06:00.0: [drm] fb0: amdgpu frame buffer device
[ 7.223883] amdgpu 0000:06:00.0: amdgpu: ring gfx uses VM inv eng 0 on hub 0
[ 7.223907] amdgpu 0000:06:00.0: amdgpu: ring comp_1.0.0 uses VM inv eng 1 on hub 0
[ 7.223929] amdgpu 0000:06:00.0: amdgpu: ring comp_1.1.0 uses VM inv eng 4 on hub 0
[ 7.223946] amdgpu 0000:06:00.0: amdgpu: ring comp_1.2.0 uses VM inv eng 5 on hub 0
[ 7.223963] amdgpu 0000:06:00.0: amdgpu: ring comp_1.3.0 uses VM inv eng 6 on hub 0
[ 7.223980] amdgpu 0000:06:00.0: amdgpu: ring comp_1.0.1 uses VM inv eng 7 on hub 0
[ 7.223997] amdgpu 0000:06:00.0: amdgpu: ring comp_1.1.1 uses VM inv eng 8 on hub 0
[ 7.224014] amdgpu 0000:06:00.0: amdgpu: ring comp_1.2.1 uses VM inv eng 9 on hub 0
[ 7.224031] amdgpu 0000:06:00.0: amdgpu: ring comp_1.3.1 uses VM inv eng 10 on hub 0
[ 7.224048] amdgpu 0000:06:00.0: amdgpu: ring kiq_2.1.0 uses VM inv eng 11 on hub 0
[ 7.224065] amdgpu 0000:06:00.0: amdgpu: ring sdma0 uses VM inv eng 0 on hub 1
[ 7.224089] amdgpu 0000:06:00.0: amdgpu: ring vcn_dec uses VM inv eng 1 on hub 1
[ 7.224106] amdgpu 0000:06:00.0: amdgpu: ring vcn_enc0 uses VM inv eng 4 on hub 1
[ 7.224123] amdgpu 0000:06:00.0: amdgpu: ring vcn_enc1 uses VM inv eng 5 on hub 1
[ 7.224140] amdgpu 0000:06:00.0: amdgpu: ring jpeg_dec uses VM inv eng 6 on hub 1
[ 7.225750] [drm] Initialized amdgpu 3.42.0 20150101 for 0000:06:00.0 on minor 1latest?d=yIl2AUoC8zA latest?i=VlpHBbQI0h0:OGDBkNfrfIs:F7zBnMy latest?i=VlpHBbQI0h0:OGDBkNfrfIs:V_sGLiP latest?d=qj6IDK7rITs latest?i=VlpHBbQI0h0:OGDBkNfrfIs:gIN9vFwVlpHBbQI0h0
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