backlight stuck at 100% (sort of)

itti · 2011-10-08 11:03:32

Hi,

I'm trying to run Arch on my new Samsung E3520. Everything works good so far with the exception of the backlight handling. There is an entry present at

/sys/class/backlight

and I'm able to control the backlight as root like this:

echo 3 > /sys/class/backlight/acpi_video0/brightness

The problem is that the fn keys for brightness do not work as expected. The gnome OSD popup does appear but the actual brightness remains at the fullest. The next thing I tried is using xbacklight and this does work as long as I do assign a direct brightness value. The commands for increase and decrease revert the brigthness to 100% and even a simple

xbacklight -get

does change the brightness to 100% again.

I tested the kernel boot parameter

acpi_backlight=vendor

but this leaves me completely without backlight controls.

Someone got any further ideas?

connexion2000 · 2011-10-08 13:44:08

Anything like laptop mode tools?
Do you use gnome 3?
In control panel there is screen section, please look there.

Shark · 2011-10-08 14:06:04

You could use xbacklight command. Check this out https://wiki.archlinux.org/index.php/Ba … xbacklight and then you can assign your brightness keys. But this will work only in X environment - not in konsole.

Last edited by Shark (2011-10-08 14:07:18)

itti · 2011-10-08 14:37:37

@connexion2000:

I do use laptop mode tools, right. But at the moment I'm running of AC and therefore laptop mode tools is disabled. Do laptop mode tools provide additional backlight related facilities other than automatic dimming?

I actually don't use gnome3 but awesome wm instead. The gnome settings daemon is running in the background though for gtk applications. I did look into the gnome control center screen section but there is nothing backlight related there - neither is in the power section.

@shark:

As mentioned earlier I'm able to _set_ backlight percentage via xbacklight. The increment, decrement and even the "get" commands seem to cause the backlight to jump up to 100% again. I guess this is what happens too when I use the default fn keys to increase/decrease brightness.

Last edited by itti (2011-10-08 14:38:20)

Shark · 2011-10-08 15:10:53

laptop-mode can be enabled when laptop is on AC.

I have somehow missed the info that you use xbacklight

Last edited by Shark (2011-10-08 15:13:15)

connexion2000 · 2011-10-09 09:59:19

itti wrote:

@connexion2000:
I do use laptop mode tools, right. But at the moment I'm running of AC and therefore laptop mode tools is disabled. Do laptop mode tools provide additional backlight related facilities other than automatic dimming?
I actually don't use gnome3 but awesome wm instead. The gnome settings daemon is running in the background though for gtk applications. I did look into the gnome control center screen section but there is nothing backlight related there - neither is in the power section.

I don't use awsome WM, but in gnome control center, I have dimming control in Screen section. I had similar problem and it was my solution.

itti · 2011-10-10 15:55:23

Ah sorry I didn't look right. There are multiple "screen" sections in the control center and yes I am able to adjust the brigthness with the appropriate slider. Sadly the fn keys still can't be used as they revert the brightness back to 100%.

Last edited by itti (2011-10-10 15:56:18)

Arch Linux

#1 2011-10-08 11:03:32

backlight stuck at 100% (sort of)

#2 2011-10-08 13:44:08

Re: backlight stuck at 100% (sort of)

#3 2011-10-08 14:06:04

Re: backlight stuck at 100% (sort of)

#4 2011-10-08 14:37:37

Re: backlight stuck at 100% (sort of)

#5 2011-10-08 15:10:53

Re: backlight stuck at 100% (sort of)

#6 2011-10-09 09:59:19

Re: backlight stuck at 100% (sort of)

#7 2011-10-10 15:55:23

Re: backlight stuck at 100% (sort of)

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