[Bug 203905] amdgpu:actual_brightness has unreal/wrong value

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=203905

--- Comment #22 from Antony J.R (antonyjr000 at gmail.com) ---
A workaround for this is done by the OpenSUSE folks, Please see
https://bugzilla.opensuse.org/show_bug.cgi?id=1180749

The only distro which fixes this is OpenSUSE. This is because there is a
bug in the mainline kernel and kernel devs are not responding to us for
some reason(maybe file a new issue???).

The problem is that the kernel uses aux for backlight control but our
systems don't support backlight control via aux. So disabling aux
completely from amdgpu kernel module can give us backlight control for the
iGPU. I've tested it and it works just find.

Regards,
Antony J.R

On Mon, Feb 8, 2021 at 3:47 AM <bugzilla-daemon at bugzilla.kernel.org> wrote:

> https://bugzilla.kernel.org/show_bug.cgi?id=203905
>
> Paulo Nascimento (paulo.ulusu at googlemail.com) changed:
>
>            What    |Removed                     |Added
>
> ----------------------------------------------------------------------------
>                  CC|                            |
> paulo.ulusu at googlemail.com
>
> --- Comment #21 from Paulo Nascimento (paulo.ulusu at googlemail.com) ---
> I confirm that the bug is not fixed in kenel 5.11-rc3
>
> max brightness:
> [pn at pn-legion backlight]$ cat
> /sys/class/backlight/amdgpu_bl1/actual_brightness
> 311
> [pn at pn-legion backlight]$ cat /sys/class/backlight/amdgpu_bl1/brightness
> 255
> [pn at pn-legion backlight]$ cat
> /sys/class/backlight/amdgpu_bl1/max_brightness
> 255
>
> min brightness:
> [pn at pn-legion backlight]$ cat
> /sys/class/backlight/amdgpu_bl1/actual_brightness
> 311
> [pn at pn-legion backlight]$ cat /sys/class/backlight/amdgpu_bl1/brightness
> 0
> [pn at pn-legion backlight]$ cat
> /sys/class/backlight/amdgpu_bl1/max_brightness
> 255
>
> My laptop has an amd ryzen 5 4600h with renoir igpu and nvidia dgpu.
> Tests are done with renoir igpu:
>
> [pn at pn-legion backlight]$ inxi -G
> Graphics:  Device-1: NVIDIA TU116M [GeForce GTX 1660 Ti Mobile] driver:
> nouveau
> v: kernel
>            Device-2: Advanced Micro Devices [AMD/ATI] Renoir driver:
> amdgpu v:
> kernel
>            Device-3: Chicony Integrated Camera type: USB driver: uvcvideo
>            Display: x11 server: X.Org 1.20.10 driver: loaded:
> amdgpu,ati,modesetting,nouveau resolution: 1920x1080~120Hz
>            OpenGL: renderer: AMD RENOIR (DRM 3.40.0 5.11.0-1-MANJARO LLVM
> 11.0.1) v: 4.6 Mesa 20.3.3
>
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