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Problems with brightness control [solved]
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Scorpion265
Tux's lil' helper
Tux's lil' helper


Joined: 05 May 2005
Posts: 129
Location: Kansas City, MO

PostPosted: Tue Feb 07, 2012 2:52 am    Post subject: Problems with brightness control [solved] Reply with quote

Hello all,

I've got a lenovo u260. about 5 months ago I had full screen brightness control. I reinstalled win 7 on it to lend to my folks to use for a while. Now that I have it back I've installed linux, have everything working except for screen brightness control. I have two levels of brightness, and it always defaults to low brightness. When I had this configured before I had HAL enabled, and this was before the 3.x series kernel.

lspci:
00:02.0 VGA compatible controller: Intel Corporation Core Processor Integrated Graphics Controller (rev 02)

This is the core i3 version of the laptop.

Any help would be appreciated.


Last edited by Scorpion265 on Wed Feb 08, 2012 3:37 am; edited 1 time in total
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smartass
Apprentice
Apprentice


Joined: 04 Jul 2011
Posts: 189
Location: right behind you ... (you did turn around, didn't you?)

PostPosted: Tue Feb 07, 2012 9:09 am    Post subject: Reply with quote

Hi, first you have to provide more info

  1. what is your goal or preferred way of controlling the brightness?
    If through your DE, then which do you use?
  2. as you have a Intel integrated GFX card, what does the "notebook manual" say about the module? like Intel GMA 4****
  3. do the brightness control keys work even in a TTY console? that would mean that they are controlled hardware-wise and any software attempting to control brightness could mess things up. Som of may friends with Lenovo Thinkpads and KDE solved such an issue by disabling the control keys in the KDE keybinings menu somewhere, before both software and hardrae changed brigtness, so they had 3 steps instead of 10 or so.
  4. the xbacklight utility is a simple way to debug
  5. have you tried writing (as root) to files in subdirectories of /sys/class/backlight/ ?


I had a similar problem with my Acer Extensa 5632z, also has an integrated Intel GMA 4500M
The solution was to add
Code:
acpi_osi=Linux
to the kernel boot parameters. It instructs the kernel to report itself to the BIOS properly and BIOS then provides the right interface.
I don't use a DE, so I just bound xbacklight +12% to my function keys through my WM.

A strange thing was that with a parameter
Code:
acpi_osi=
the function keys worked hardware-wise, but couldn't be controlled by software or the /sys interface.

Try both these forms of the parameter and see which works best for you.

Good luck :)
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Scorpion265
Tux's lil' helper
Tux's lil' helper


Joined: 05 May 2005
Posts: 129
Location: Kansas City, MO

PostPosted: Wed Feb 08, 2012 3:36 am    Post subject: Reply with quote

Bless you! The acpi_osi= flag worked for both the console and the window manager (so i am assuming hardware took over). Thanks so much!
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