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In my HP Folio 13 laptop with Ubuntu 13.04 the brightness control works with the slider in the system Brightness & Lock settings, but the brightness function keys don't. Also, the brightness level is set to maximum on every boot.

Is there a way to make them work and make the system keep the brightness level set in the previous session?

Some information about my laptop concering this issue:

ls /sys/class/backlight
intel_backlight

ls /sys/class/backlight/*/brightness
/sys/class/backlight/intel_backlight/brightness

lspci | grep -i vga
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)

uname -a
Linux folio13 3.8.0-19-generic #29-Ubuntu SMP Wed Apr 17 18:16:28 UTC 2013 x86_64 GNU/Linux
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4 Answers 4

up vote 2 down vote accepted

Guys it worked for me with this setting in /etc/default/grub :

GRUB_CMDLINE_LINUX_DEFAULT="acpi_osi="

Yep, this is empty value for acpi_osi...

Don't forget to do sudo update-grub and restart after you edit the /etc/default/grub file.

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Well in my case on pressing Fn + <Brightness Keys> I could see the brightness indicator on the top but brightness wasn't changing at all. I tried what you suggested and after restarting it wasn't even showing the indicator. I removed that line from grub and updated again, restarted and bam! It worked! :) So I guess just running update-grub may solve issue for some. Thanks for that though, I could find a way because of this. :) –  Suraj Bajaj Jul 27 '13 at 15:00
    
For me, it reads GRUB_CMDLINE_LINUX_DEFAULT="quiet splash". I tried instead changing GRUB_CMDLINE_LINUX="acpi_backlight=vendor" to GRUB_CMDLINE_LINUX="acpi_backlight=vendor acpi_osi=", but that didn't boot correctly. Instead, GRUB_CMDLINE_LINUX="acpi_backlight=vendor acpi_osi=''" works and also re-enables the wireless switch on the F12 key. That approach seems better than taking the side effects of removing quiet splash from the GRUB command line. –  Firefeather Sep 28 '13 at 18:12

To make the brightness function keys work on my laptop I have tried the following configurations (one by one) in /etc/default/grub, but none of them worked:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash pcie_aspm=force acpi_backlight=vendor"
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=linux acpi_backlight=vendor"
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor"

Same thing for the GRUB_CMDLINE_LINUX variable.

I read about a solution which suggested editing /etc/X11/xorg.conf, but there was no such file in my system.

So far the best workaround I have found is to use xbacklight to bind the keys to appropriate commands. This will enable you to easily increase/decrease the brightness, but it won't show the brightness indicator while you do that.

1) Install xbacklight by running:

sudo apt-get install xbacklight -y

2) Go into System Settings > Keyboard > Shortcuts > Custom Shortcuts

3) Add the following bindings:

Brightness Down = xbacklight -10
Brightness Up = xbacklight +10

4) Click on "Disabled" and press your preferred combinations (for me CTRL+F2 and CTRL+F3 works fine)

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This is a bug that has been recently been addressed: https://bugs.launchpad.net/ubuntu/+source/upower/+bug/994745

It is associated with the upstream kernel bug of problems with unplugging not being recognised: https://bugzilla.kernel.org/show_bug.cgi?id=54621

Hopefully this can be backported to the Raring kernel in the near future.

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I don't have the power indicator problem which occurs in the bugs you mentioned. It appears though that the patch provided in comment #28 of bugzilla fixes also the two special keys for brightness +/- as well as the wireless adapter toggle. I wonder whether there is an easy way to apply that without having to wait for it to be backported. –  Krige Apr 26 '13 at 11:06

I wanted to add a fix that worked for me, because I couldn't find this solution anywhere.

If you have an Intel video card (HD 4000, for example) you can fix it by adding acpi_backlight=intel_backlight to your grub options (in the same way as above).

BEFORE YOU DO THIS: Test that you actually have an Intel video card with the following command:

echo 200 > /sys/class/backlight/intel_backlight/brightness

If your brightness changes, then this solution should work for you.

Please note that I haven't tested this solution for laptops with multiple video cards (like NVidia Optimus or the like).

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