Possible bug in acpi_video(4)

[Andriy Gapon]

On 28/05/2020 13:02, MrPhyber wrote:
> 
> I tried the patch you sent, and I have a few questions:
> 1) when will this patch be avaiable on 12.1-RELEASE?

In stable/12 soon.
In 12.1 probably never as the release has been released.

> 2) now the system does not spit out any more errors like
> the one complaining about _BQC missing: in fact it doesn't
> give errors at all, but the hardware brightness controls still
> won't work. Now hw.acpi.video.lcd0.active = 1 but if I try
> to modify hw.acpi.video.lcd0.brightness nothing appens. I
> still think that acpi_video doesn't see all video outputs
> (I investigated a bit further and on OpenBSD there are
> acpivouts on dmesg output, could be an hint). What could
> be wrong?

If your system is like mine then ACPI does not directly control the brightness.
Instead, it posts some events that a video driver (like radeon or amdgpu) is
supposed to listen to and then the driver should update the brightness.
(This can also be thought of as the brightness being controlled by the video
"card" / GPU rather than by a motherboard).
For my laptop I had to patch amdgpu driver:
https://github.com/FreeBSDDesktop/kms-drm/pull/241


-- 
Andriy Gapon