LinuxQuestions.org - [SOLVED] [Solved] Brightness set to zero in Salix OS on eMachines with Intel's GMA4500

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- Slackware (https://www.linuxquestions.org/questions/slackware-14/)

- - [Solved] Brightness set to zero in Salix OS on eMachines with Intel's GMA4500 (https://www.linuxquestions.org/questions/slackware-14/%5Bsolved%5D-brightness-set-to-zero-in-salix-os-on-emachines-with-intels-gma4500-902983/)

Z0K4	09-14-2011 08:36 AM

[Solved] Brightness set to zero in Salix OS on eMachines with Intel's GMA4500

Greetings forum!

So, I have a problem: I just finished installing Salix OS on my eMachines laptop. I didn't encounter any problems during the installation, but after rebooting, screen brightness is set to 0! I tried with Fn keys but they didn't help... I think it's kernel thing because I tried Ubuntu Live CD and the result was the same: backlight turned off!

Salix is fully backward compatible with Slackware so there should be no problems applying your solutions for Slackware to Salix OS.

Thank you in advance!

macemoneta

09-14-2011 09:38 AM

Take a look in /sys/class/backlight/ - you should see a 'brightness' entry. If you cat it, you will get the current value. You can set it with something like:

Code:

echo -n 5 > /sys/class/backlight/xxxx/brightness

If that works, you can place the command in your rc.local so it's set at system boot, or in .bash_profile to set it at login (or both).

Z0K4	09-14-2011 10:03 AM

Quote:

Originally Posted by macemoneta (Post 4471492)

Take a look in /sys/class/backlight/ - you should see a 'brightness' entry. If you cat it, you will get the current value. You can set it with something like:

Code:

echo -n 5 > /sys/class/backlight/xxxx/brightness

If that works, you can place the command in your rc.local so it's set at system boot, or in .bash_profile to set it at login (or both).

Unfortunately this didn't work. I found brightness entry and used cat command! Value was 9 so I did as you sad:

Code:

echo -n 5 > /sys/class/backlight/acpi_video0/brightness

Brightness was still at 0, so instead of 5 I've put 50 it returned wrong argument or something like that! So I put it back to 9. Do you have any other suggestions?

Thank you for your help!

macemoneta

09-14-2011 10:11 AM

Some eMachines require that a kernel parameter be added to whatever bootloader you are using:

Code:

acpi_osi=Linux

Alien Bob

09-14-2011 10:19 AM

Quote:

Originally Posted by Z0K4 (Post 4471452)

Greetings forum!

Salix is fully backward compatible with Slackware so there should be no problems applying your solutions for Slackware to Salix OS.

Did you try installing Slackware on that machine to see whether your statement is actually true?

Eric

Z0K4	09-14-2011 10:20 AM

Quote:

Originally Posted by macemoneta (Post 4471529)

Some eMachines require that a kernel parameter be added to whatever bootloader you are using:

Code:

acpi_osi=Linux

I use LiLo. Can you tell me how can I edit the configuration file and what to do after that?

Z0K4	09-14-2011 10:24 AM

Quote:

Originally Posted by Alien Bob (Post 4471534)

Did you try installing Slackware on that machine to see whether your statement is actually true?

Eric

Well, no... Hell, I don't even know how to install Slackware. That's what I was told, that they are compatible and that both slackers and Salix users benefit from each other! If I'm wrong I apologize! ;)

allend

09-14-2011 10:30 AM

Quote:

Brightness was still at 0, so instead of 5 I've put 50 it returned wrong argument or something like that! So I put it back to 9.

On my eMachines EM250 (not yours as you have a different graphics chipset),when I do 'cat /sys/class/backlight/acpi_video0/max_brightness', the value returned is 9.
It seems that the maximum brightness is already set on your machine.

Oh, and with Slackware, I have no problems with brightness. Function keys work as advertised. KDE power management brightness settings are obeyed.

macemoneta

09-14-2011 10:43 AM

Quote:

Originally Posted by Z0K4 (Post 4471537)

I use LiLo. Can you tell me how can I edit the configuration file and what to do after that?

Edit /etc/lilo.conf and add the parameter to the 'append=' (add it if needed). For example:

Code:

image=/boot/vmlinuz-XXXXXXX

  label=linux

  read-only

  root=/dev/hdaX

  initrd=/boot/initrd-XXXXXX.img

  append="someOption someOtherOption acpi_osi=Linux"

Then rerun the lilo command to update the boot.

allend

09-14-2011 11:15 AM

For some other possibilities, if the fix suggested by macemoneta does not work, see here. http://ubuntuforums.org/showthread.php?p=10591451

Z0K4	09-14-2011 11:25 AM

Quote:

Originally Posted by macemoneta (Post 4471557)

Edit /etc/lilo.conf and add the parameter to the 'append=' (add it if needed).

Then rerun the lilo command to update the boot.

I added acpi_osi=Linux to append and after that:

Code:

/sbin/lilo

then rebooted but nothing changed... unfortunately.
Should I remove acpi_osi=Linux from append, or just leave it there?

Quote:

Originally Posted by allend (Post 4471550)

My Fn keys also work, I mean, I can barely see that but when I hit proper combination it says that screen brightness is changed but it's not. I also want Slackware, but I don't know nothing about it! That is way I choose Slackware based distribution that is more or less compatible with Slackware.

Quote:

Originally Posted by allend (Post 4471584)

For some other possibilities, if the fix suggested by macemoneta does not work, see here. http://ubuntuforums.org/showthread.php?p=10591451

Thank you I'll check this out!

macemoneta

09-14-2011 11:31 AM

Quote:

Originally Posted by Z0K4 (Post 4471595)

I added acpi_osi=Linux to append and after that:

Code:

/sbin/lilo

then rebooted but nothing changed... unfortunately.
Should I remove acpi_osi=Linux from append, or just leave it there?

If it's not working, and you can't see any change in /sys behavior, then you might as well remove it.

dr.s	09-14-2011 06:10 PM

You might want to try this kernel parameter

Code:

acpi_backlight=vendor

Z0K4	09-15-2011 01:22 AM

Quote:

Originally Posted by dr.s (Post 4471910)

You might want to try this kernel parameter

Code:

acpi_backlight=vendor

I've tried that one last night. It only disabled my Fn +/- brightness key!
What did help me was this code (must be super user):

Code:

setpci -s 00:02.0 F4.B=7F

Now brightness is always at 40-50% till I reboot, and then is reset to 0%... I even don't know what this code stands for, does it harm my hardware... because I can see hexadecimal code, and something similar is used in asembler language!

Thank you for your help guys! Any other ideas?

Regards! ;)

allend

09-15-2011 09:16 AM

Just found another link that is relevant. http://forums.gentoo.org/viewtopic-t...6-start-0.html
Appears to be a bug that will need to be addressed upstream.
The command simply writes to the pci register that controls the backlight. I do not see how it will do any damage.
You could try writing F4.B=00 and see whether it affects your brightness level.

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