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#1 2012-09-12 15:01:06

fifas
Member
Registered: 2012-09-12
Posts: 20

Laptop low screen brightness on battery

Hello!

I have just install Crunchbang 11 (Statler) on my 64 bit. laptop. And I have problem. Every time I put my laptop on battery, system reduces my screen brightness.
   I checked Xfce-power-manager and it shows that my monitor brightness level is 20% (on AC 80%). I tried to change these number but it didn't worked out. Next time I open manager it show the same numbers (20%).
   I also tried modify xfce4-power-manager.xml file but it also didn't worked out.
I was wondering maybe somebody knows how to make system not reduce screen brightness than laptop is on battery? Thanks for help.

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#2 2012-09-12 16:09:14

lcafiero
The #! Guy
From: Felton, California, USA
Registered: 2011-07-21
Posts: 2,205
Website

Re: Laptop low screen brightness on battery

Hello, fifas, and welcome to CrunchBang.

Since we don't know your hardware specifics, you might want to start with this thread from the Debian forums:

http://forums.debian.net/viewtopic.php?f=7&t=62521

In short, it suggests adding this option

acpi_backlight=vendor

to the end of the line in grub, and then reboot (always a good practice when changing something like this).

If that doesn't work, here's a copy of my  ~/lcafiero/.config/xfce4/xfconf/xfce-perchannel-xml/xfce4-power-manager.xml file

 <?xml version="1.0" encoding="UTF-8"?>

<channel name="xfce4-power-manager" version="1.0">
  <property name="xfce4-power-manager" type="empty">
    <property name="power-button-action" type="empty"/>
    <property name="critical-power-action" type="uint" value="4"/>
    <property name="dpms-on-battery-sleep" type="uint" value="0"/>
    <property name="brightness-on-battery" type="uint" value="9"/>
    <property name="dpms-on-battery-off" type="uint" value="0"/>
    <property name="critical-power-level" type="uint" value="15"/>
    <property name="dpms-on-ac-sleep" type="uint" value="20"/>
    <property name="dpms-on-ac-off" type="uint" value="21"/>
  </property>
</channel> 

I post this because I don't have any change in screen performance of my laptop, AC or battery. On the "brightness on battery" above, how does this compare with your file?

Hope this helps.


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#3 2012-09-13 13:12:31

fifas
Member
Registered: 2012-09-12
Posts: 20

Re: Laptop low screen brightness on battery

Thanks for you reply Icafiero!
  Sadly, but trick with xfce4-power-manager.xml file not works. However, it looks that after rebooting my brightness on battery is fine (or than I turn on laptop then it is on battery). It reduces brightness only than I unplugin AC power.  So it looks not so big problem.
  Now about grub. What exactly grub file should I modify? I am asking because I could not find /etc/grub.cong file. Thanks for you replies.

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#4 2012-10-10 05:23:30

shem
#! Member
From: Universe 6.62606957(29)×10−34
Registered: 2012-05-16
Posts: 78

Re: Laptop low screen brightness on battery

fifas wrote:

Now about grub. What exactly grub file should I modify? I am asking because I could not find /etc/grub.cong file. Thanks for you replies.

Maybe reply is too late, but changes to grub2 should be made in '/etc/default/grub'. Afterwards, as commented in the file, run 'update-grub'

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