change brightness

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change brightness

Postby boda on Fri Jul 27, 2012 7:02 am

Hi,

Here's some system information to start with:

Linux mint 12 32-bit
xfce 4.8
kernel: 3.0.0-12-generic

Graphics card info from command lspci:

00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)

Graphics card driver info from command inxi -Gx
Graphics: Card: Intel 2nd Generation Core Processor Family Integrated Graphics Controller bus-ID: 00:02.0
X.Org: 1.10.4
driver: intel
Resolution: 1920x1080@60.0hz
GLX Renderer: Mesa DRI Intel Sandybridge Desktop
GLX Version 2.1: Mesa 7.11.2
Direct Rendering: Yes


Could anyone help me with this. I'm attempting to reduce the brightness on my machine to a bearable level. I've got compiz installed and have adjusted the brightness using compiz, but there are still some windows that I can't adjust with compiz, so I'm going to have to adjust the brightness output of the system. Getting blinded by the url autocomplete is not fun.


I tried the command:
setpci -s 00:02.0 F4.B=50

this didn't work, I got the following error:
pcilib: Cannot open /sys/bus/pci/devices/0000:00:02.0/config

I've assumed that issuing the boot command 'acpi_osi=Linux' won't work as this seems to be a solution for laptops, to get the hotkeys working to adjust the brightness. I'm using a desktop machine so I don't have any function keys.

I looked into writing echo values to 'sys/class/backlight'. (as in this post: http://unix.stackexchange.com/questions ... after-boot) I had a look at the 'sys/class/backlight' folder on my machine and it is empty. Why haven't I got anything in 'sys/class/backlight'?

Does anyone have any ideas how I can solve this?

Thanks.
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Re: change brightness

Postby egrath on Sat Jul 28, 2012 7:15 am

Hello,

In /sys/class/backlight there are additional folders (like acpi_video0) where you should normally find the files you are looking for (brightness, max_brightness, ...)

If your /sys/class/backlight is empty, it's probably because of a flaw in the ACPI implementation of your BIOS. Can you try upgrading your BIOS to the latest available version?

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Re: change brightness

Postby jjaythomas on Mon Jul 30, 2012 12:50 am

In XFCE panel
thers a brightness applet.

Not sure if 'Brightness' your talking about?

J.Jay

P.S. theirs also a applet called 'jupitor' that adjust brightness/battery/resolution ect. I don't think in 12.04 (LMint 13) repos but can find deb (package) on web> :wink:
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Re: change brightness

Postby jjaythomas on Mon Jul 30, 2012 12:23 pm

also...

in setting>setting editor under 'xfce4-desktop' theirs a setting for brightness of monitor I think.

J.Jay
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Re: change brightness

Postby boda on Wed Aug 01, 2012 11:20 am

Hi egrath,

I've uptaded my bios now to f8, the latest version:

Handle 0x0000, DMI type 0, 24 bytes
BIOS Information
Vendor: Award Software International, Inc.
Version: F8
Release Date: 03/27/2012
Address: 0xE0000
Runtime Size: 128 kB
ROM Size: 4096 kB
Characteristics:
PCI is supported
PNP is supported
BIOS is upgradeable
BIOS shadowing is allowed
Boot from CD is supported
Selectable boot is supported
EDD is supported
5.25"/360 KB floppy services are supported (int 13h)
5.25"/1.2 MB floppy services are supported (int 13h)
3.5"/720 KB floppy services are supported (int 13h)
3.5"/2.88 MB floppy services are supported (int 13h)
Print screen service is supported (int 5h)
8042 keyboard services are supported (int 9h)
Serial services are supported (int 14h)
Printer services are supported (int 17h)
CGA/mono video services are supported (int 10h)
ACPI is supported
USB legacy is supported
BIOS boot specification is supported
Targeted content distribution is supported


I've checked sys/class/backlight using 'ls -a' in the terminal. This folder is still empty. Any ideas on how to get the correct folders in there? The other suggestions didn't work.

Many Thanks for the reply,

boda.

egrath wrote:Hello,

In /sys/class/backlight there are additional folders (like acpi_video0) where you should normally find the files you are looking for (brightness, max_brightness, ...)

If your /sys/class/backlight is empty, it's probably because of a flaw in the ACPI implementation of your BIOS. Can you try upgrading your BIOS to the latest available version?

egrath
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Re: change brightness

Postby boda on Thu Aug 02, 2012 5:36 am

Hi,

I've seen this solution but it's not compatible with my system:

https://launchpad.net/~kamalmostafa/+ar ... gbacklight

I've tried 'xbacklight = 10 #'. and 'xbacklight - 10 '. The xbacklight controls have no effect.

I've tried adding 'acpi_osi=Linux acpi_backlight=vendor' to the grub bootloader then running 'sudo modprobe video' (to reload the backlight video kernel module). I also tried this with 'acpi_osi=Linux acpi_backlight=legacy'. This has not effect. The backlight folder remains empty.

I'm going to try and update the kernel to v3.3.8 to see if that fixes the problem.

I'll post back the results.

thanks,

boda
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Re: change brightness

Postby black veils on Thu Aug 23, 2012 10:06 am

have you tried something basic like using the keyboard keys, then restarting the computer?
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Re: change brightness

Postby jjaythomas on Thu Aug 23, 2012 4:52 pm

not sure if any help/info...

I have a tablet ('old TC1100) that not only do I need a custom script for brightness, It only responds if use the 'jog dial' to actually change settings (hardwired to that key?!)
and can't work with any other keys/shourtcut. :roll: In some distros I would even get notification pop ups that brightness was changing, but acually was't. :?:

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