Arch Linux

struq

Member

From: Guangzhou

Registered: 2007-12-29

Posts: 16

LCD brightness issue

I've installed archlinux on my laptop, everything works well except the brightness control.
The screen originally has 11 brightness levels, but when I either press Fn+F6/F7 key or use gnome-power-manager to adjust brightness, it always skips a level.

/proc/acpi/video/VGA/LCD/brightness
levels:  100 60 20 28 36 44 52 60 68 76 84 92 100
current: 100

I can only get level 20 36 52 68 84 and 100
The problem also exists in console mode.
I tried adding video module to blacklist, then brightness cannot be adjusted at all.
However, I never get this problem in openSUSE, all 11 levels are available.

Could anyone help me? Thanks!:|

meandean

Member

Registered: 2008-06-24

Posts: 67

Re: LCD brightness issue

personally I use the xbacklight command....seems to be the most reliable

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Even a chicken can install Debian, when you put enough grain on the enter key.

struq

Member

From: Guangzhou

Registered: 2007-12-29

Posts: 16

Re: LCD brightness issue

Hello,

Do you happen to have A Thinkpad laptop? I have some issues with my R60e which I think are related to your problem.

No, my laptop is HP dv2500

personally I use the xbacklight command....seems to be the most reliable

When I manage to use xbacklight
I get this

No outputs have backlight property

kclive18

Member

From: Columbus, Ohio, USA

Registered: 2008-05-08

Posts: 219

Re: LCD brightness issue

http://www.nabble.com/xbacklight:-No-ou … 62174.html

The second post in that thread there suggests that the vesa and fglrx (proprietary ATI) drivers do not support xbacklight.  If your laptop has an ATI card (my hp zv6000 does), you will need to switch to the open-source ATI drivers.

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My Rigs:
- Mid-2007 iMac 20", Intel 2GHz Core 2 Duo, 2x1GB DDR2-800, 250GB SATA HDD, and...MIGHTY MOUSE!!! , OSX 10.5 Leopard, ATI Radeon 2400XT 128MB
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struq

Member

From: Guangzhou

Registered: 2007-12-29

Posts: 16

Re: LCD brightness issue

my card is nvidia geforce 8400m gs.

kclive18

Member

From: Columbus, Ohio, USA

Registered: 2008-05-08

Posts: 219

Re: LCD brightness issue

http://forums.nvidia.com/index.php?show … t&p=386303

Hmmm...I found this on the nvidia forums:

I have a Samsung R700 laptop and my brightness stopped working after installing the restricted drivers. This is how I fixed it.

Press Ctrl-Alt-F1 to get a virtual console. Once you are in this console I think different video drivers are active so the following worked for me to adjust brightness.

Logged in and ran the following command:
echo -n 70 > /proc/acpi/video/NVID/LCD/brightness
then logged out and pressed Ctrl-Alt-F7 to go back to X

It's possible your brightness key on your laptop may work straight after you press ctrl-alt-f1 and you won't have to login and do the acpi stuff.

Also I have a startup script to set my brightness to a fixed value before X starts. It's not ideal but it's the only solution I could find that worked for me until the drivers are fixed!

Hope this helps.

Last edited by kclive18 (2008-07-08 11:19:25)

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My Rigs:
- Mid-2007 iMac 20", Intel 2GHz Core 2 Duo, 2x1GB DDR2-800, 250GB SATA HDD, and...MIGHTY MOUSE!!! , OSX 10.5 Leopard, ATI Radeon 2400XT 128MB
- HP zv6203cl, AMD Athlon 64 3200 S939, 2x512MB DDR400, 80GB 4200rpm HDD, ATI Radeon Xpress 200M 128MB, Arch i686
- 1986 Gibson SG Junior Cherry Red, Ibanez 15W amp, DigiTech RP250 modeling processor

struq

Member

From: Guangzhou

Registered: 2007-12-29

Posts: 16

Re: LCD brightness issue

They're talking about another problem.
my brightness control works out of the box, with either Fn key or gnome-power-manager, it just ignores half of the brightness levels
As I said, it was perfect on openSUSE, I tried to find some diffenrence but got nothing.
and I don't have /proc/acpi/video/NVID/LCD/brightness, but /proc/acpi/video/VGA/LCD/brightness, which is read-only.

Thanks though

I think the key to the problem can be something like a script which is executed when I press Fn key.

Last edited by struq (2008-07-08 14:01:45)

Hohoho

Member

Registered: 2007-06-23

Posts: 222

Re: LCD brightness issue

Same here, using Dell Inspiron 1520.
If I use Fn key to set up brightness it skips a level or two, so instead of 8 levels of brightness I have only 3.

neptuneK

Member

Registered: 2008-06-03

Posts: 38

Re: LCD brightness issue

Did any of you try ,
echo "<brightness level>" > /proc/acpi/video/VGA/LCD/brightness

??

Hohoho

Member

Registered: 2007-06-23

Posts: 222

Re: LCD brightness issue

echo X > /proc/acpi/video/VID/LCD/brightness does work as it should, but how can I make the function keys work right, right now they just skip a few of the levels.

Hohoho

Member

Registered: 2007-06-23

Posts: 222

Re: LCD brightness issue

Found a bugreport on ubuntu's launchpad with the same exact problem, the proposed fix that works for me is to unload the "video" module, now it works fine.