Re: GNOME brightness controls have no effect on brightness
On Sun, 3 Apr 2022 Juan R.D. Silva wrote:
Hi folks,
Debian 11 on Dell M4800 Mobile Workstation with Nvidia Quadro K2100M card.
I've been using the system with full (100%) screen brightness for rather
long time. Today I wanted to reduce it and to my astonishment found that
GNOME "progressed" to the point when even this basic feature has gone.
The function keys work, the sliders move. Everything is dandy, except it has
no effect on the actual brightness, which stack at 100%. Even setting the
brightness in BIOS to 50% instead of 100% has no effect.
Google revealed a lot of complaints but so far I've not found any really
helpful suggestion. Worse, I even couldn't find any trace of this being a
bug of some sort.
Anyone can help here? I'm getting old and my eyes sore. :-(
I'll show you what I do. I don't use GNOME, but maybe it will work.
Four steps:
1. Confirm this directory has expected contents:
$ ls -p /sys/class/backlight/acpi_video0/
actual_brightness bl_power brightness device max_brightness power/ subsystem type uevent
It has "brightness" and "max_brightness" files. So far so good.
2. Find out what counts as maximum brightness. (I think I have seen
this vary from laptop to laptop):
$ cat /sys/class/backlight/acpi_video0/max_brightness
7
3. Find out what value current brightness is:
$ cat /sys/class/backlight/acpi_video0/brightness
5
4. As root, write some value less-than-or-equal-to maximum brightness
(found in step 2) into "brightness" file. For example, when 5 is too
bright, I might try replacing that with 4.
# echo -n 4 > /sys/class/backlight/acpi_video0/brightness
That is all.
Hope this helps.
Sorry for the rant but it looks that either GNOME folks decided they
know it best what it should be for everyone or they are so busy with
frequent "nice" GUI changes and re-designs that there is no time
left for actual functionality. Fake controls and sliders doing
nothing?.. This is really climax.
I have no patience for figuring out where graphical desktops hide (or
document) their "user friendly" configuration tools, so I can
sympathise.
Something like the above procedure (maybe with some extra exploration
of /sys/class) has always worked for me.
Good luck. Hope this helps.
--
Ce qui est important est rarement urgent
et ce qui est urgent est rarement important
-- Dwight David Eisenhower
Reply to: