Re: Could not change brightness anymore with i915kms & acpi_video modules c 202211

From: Emmanuel Vadot <manu_at_bidouilliste.com>
Date: Tue, 31 Jan 2023 12:55:26 UTC
On Tue, 31 Jan 2023 12:33:02 +0000
"Poul-Henning Kamp" <phk@phk.freebsd.dk> wrote:

> --------
> Oleksandr Kryvulia writes:
> 
> > Does backlight(8) works for you?
> 
> Speaking of backlight(8):  On my T14s, I see the following:
> 
> If I set the light with backlight(8) to something, say 30%, and then
> change the power-situation, for instance by unplugging the charger,
> the backlight goes up to 100%.
> 
> If I then try to set it back to 30% with backlight(8), nothing happens.
> 
> If I use any other value, for instance 31%, backlight(8) does the job.
> 
> I guess somewhere some code says "It's always 30%, just return" ?
> 
> This might be a bit confusing if you have the intensity encoded in
> some script, which then "sometimes does not work"...

 Smells like
https://cgit.freebsd.org/src/commit/sys/dev/backlight/backlight.c?id=e26ef41f79902991c772b59927c721aa7fa5fc64
 It's not in 13.1 but will be in 13.2

> 
> -- 
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk@FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe    
> Never attribute to malice what can adequately be explained by incompetence.
> 


-- 
Emmanuel Vadot <manu@bidouilliste.com> <manu@FreeBSD.org>