Arch Linux

awarrenlove

Member

From: NC, US

Registered: 2013-08-08

Posts: 4

Backlight keys no longer work after upgrade to kernel 3.10.x

The solution to this may be RTFM or because I'm a newbie, so please be gentle.

After upgrading to any of the 3.10.x kernel versions, the backlight keys in XFCE that worked with version 3.9 no longer change the backlight. The backlight graphic still comes up, but nothing actually changes. What is necessary for that to change the backlight?

I have upgraded the Intel video drivers, but have no modules that look like video modules in either lsmod or even in the

/usr/lib/modules

directory. That may be normal though. I don't know if there was something there with the old kernel.

I ran

lspci | grep VGA

and this was the output

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

I have also tried it with and without xfce4-power-manager running since it looks like that controls backlight.

Some more background, I am using SLiM to start XFCE4 on a Lenovo Z570.

Does anyone know what I should check to see what's going on? If I need to, I can boot into a disc and manually downgrade, although I'd prefer to at least learn what's going on so I can fix it (and know more about Linux/Arch in the process).

jasonwryan

Anarchist

From: .nz

Registered: 2009-05-09

Posts: 30,424

Website

Re: Backlight keys no longer work after upgrade to kernel 3.10.x

Can you change them manually by echo'ing a higher/lower value to /sys/class/whatever?

---

Arch + dwm   •   Mercurial repos  •   Surfraw

Registered Linux User #482438

Pse

Member

Registered: 2008-03-15

Posts: 413

Re: Backlight keys no longer work after upgrade to kernel 3.10.x

On my Intel laptop I found it necessary to add the following line in the devices section of xorg.conf:

 Option      "Backlight"  "intel_backlight"

If that doesn't work, add the following setting to your kernel command line:

acpi_osi=Linux

You may also try with:

acpi_osi="!Windows 2012"

awarrenlove

Member

From: NC, US

Registered: 2013-08-08

Posts: 4

Re: Backlight keys no longer work after upgrade to kernel 3.10.x

@jasonwryan Yes I can.

@Pse The xorg configuration solution worked perfectly. Thank you. Any idea why this would be required now but not for the previous kernel?

WonderWoofy

Member

From: Los Gatos, CA

Registered: 2012-05-19

Posts: 8,414

Re: Backlight keys no longer work after upgrade to kernel 3.10.x

@Pse The xorg configuration solution worked perfectly. Thank you. Any idea why this would be required now but not for the previous kernel?

http://www.linuxjournal.com/content/jul … ernel-news

About half way down it talks about the backlight and how the new way in which windows 8 handles things affects other systems (negatively).

I just want to also point out, for any other backlight issue sufferers finding their way here, that telling acpi that it is nothing also seems to work in some cases.  That is, use "acpi_osi= ".  I had been using acpi_osi="!Windows 2012", which in my case worked great, but just realized the other day that using nothing at all seems to bring about the same solution.