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#1 2012-10-21 12:55:51

Defolos
Member
Registered: 2012-09-21
Posts: 8

screen backlight brightness issues

Hi,
I have a problem with KDE and setting the backlight brightness. The problem is the following: When I boot the laptop and log in on a tty I can change the backlight brightness via keyboard shortcut and setting /sys/class/backlight/acpi_video0/brightness. However when I start KDE via startx, then none of both options longer work. Also using the slider in the KDE power manager does not work. Even if I stop X and go back to a tty, I cannot change the backlight brightness anymore.

The laptop is a HP Compaq 8710w, if it helps.

Anyone an idea what the issue could be?


Thanks in advance,
Defolos

Last edited by Defolos (2012-10-21 15:20:48)

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#2 2012-10-21 15:22:15

Defolos
Member
Registered: 2012-09-21
Posts: 8

Re: screen backlight brightness issues

I found out that this is not only a KDE problem, also after starting GNOME I cannot change the backlight brightness.
As far as I remember I upgraded the proprietary nvidia driver yesterday, could it be a problem with the driver?

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#3 2012-10-21 17:34:11

Selo
Member
Registered: 2012-02-08
Posts: 36

Re: screen backlight brightness issues

I am having the same problem. I can change backlight with fn+brightness up/down keys, but i am not able to change it via power manager in KDE. I also did upgrade the nvidia proprietary  driver yesterday. This could be nvidia related, i guess.

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#4 2012-10-21 17:49:01

Defolos
Member
Registered: 2012-09-21
Posts: 8

Re: screen backlight brightness issues

You could try this: https://wiki.archlinux.org/index.php/NV … ss_Control maybe it will work for you, unfortunately it didn't for me.

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#5 2012-10-21 20:20:22

Selo
Member
Registered: 2012-02-08
Posts: 36

Re: screen backlight brightness issues

Tried it, no joy sad

Edit : dim display and switch off display doesn't work either.

Last edited by Selo (2012-10-21 20:25:52)

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#6 2012-10-21 20:42:49

rp9
Member
From: Austria
Registered: 2010-09-16
Posts: 13

Re: screen backlight brightness issues

same probleme here probook 5320m
also volume fn keys stopped working

setting brightness from gnome settings works

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#7 2012-10-22 09:51:00

Selo
Member
Registered: 2012-02-08
Posts: 36

Re: screen backlight brightness issues

It's a nvidia releated bug for sure. I downgraded my driver and everything works now. If you have not cleaned pacman cache following code should also work for you,

sudo pacman -U /var/cache/pacman/pkg/nvidia-304.51-4-x86_64.pkg.tar.xz /var/cache/pacman/pkg/nvidia-utils-304.51-1-x86_64.pkg.tar.xz

reboot for changes to take affect.

Same problem is also discussed here [SOLVED*][Samsung RV520]NVIDIA driver 304.60 Brightness problem

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#8 2012-10-22 12:25:09

A.J.Rouvoet
Member
From: Naaldwijk, The Netherlands
Registered: 2012-06-30
Posts: 35
Website

Re: screen backlight brightness issues

I had the same problem. But I narrowed it down a bit by looking at /var/log/messages.log

$ tail -f /var/log/messages.log
$ # use the brightness buttons

Oct 22 13:58:06 Fenix logger: ACPI group/action undefined: video/brightnessdown / BRTDN
Oct 22 13:58:06 Fenix logger: ACPI group/action undefined: video/brightnessup / BRTUP

I'm not sure how this used to function, but I'm assuming ACPI intercepts these events now and doesn't do anything with it.

This https://wiki.archlinux.org/index.php/Talk:MacBookPro helped me to get to a solution. Make sure you replace the BRIGHTNESS_BASE variable by the one your system uses. (probably /sys/class/backlight/acpi_video0)

The author of the wiki mentions this is a "quick/dirty" fix. If somebody has a better solution, please let me know.

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