[SOLVED] Backlight keys not working

gsingh93 · 2013-07-22 17:18:50

The backlight keys on my laptop aren't working in arch. xbacklight also does not work. Both of these things work in Ubuntu. Here is my GRUB_CMDLINE_LINUX_DEFAULT:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash pcie_aspm=force i915.i915_enable_rc6=1 i915.i915_enable_fbc=1 i915.lvds_downclock=1 acpi_backlight=vendor acpi_osi=Linux radeon.modeset=1"

When I installed Ubuntu, I had to add "acpi_backlight=vendor acpi_osi=Linux", although that doesn't seem to be helping here.

in /sys/class/backlight I see acpi_video0, acpi_video1, and intel_backlight. After echoing values into all of them, only intel_backlight seems to do anything. On Ubuntu, the only thing I see in that folder is intel_backlight.

Does anyone have any suggestions? The wiki doesn't have anything I haven't already tried.

Last edited by gsingh93 (2013-07-23 16:02:39)

WonderWoofy · 2013-07-22 17:27:44

So you have tried everything on the intel wiki page? Does that include adding the line to the /etc/X11/xorg.conf.d/20-intel.conf file?

For me acpi_osi="!Windows 2012" works. But with grub, you need to be careful about how you use the double quotes. I have heard that single quotes will work as well though, I have just never had the need to try.

Hurricane · 2013-07-23 04:09:33

This could be a kernel issue. I read on the Linux google+ RSS feed that 3.11-rc2 (which just came out) fixes a backlight issue. If all else fails, you could try compiling the latest kernel, if the backlight issue is really that important. But don't take my word for it, because my laptop doesn't have a backlight.

WonderWoofy · 2013-07-23 04:38:14

I am running 3.11 rc2 right now, and I still have to use the acpi_osi="!Windows 2012" to make things work.

BTW, @OP, what kind of computer is it?

gsingh93 · 2013-07-23 16:02:23

I figured it out.

I confirmed from Xorg.0.log that acpi_video1 was being used instead of intel_backlight. However, I had already tried the fix here: http://bugs.debian.org/cgi-bin/bugrepor … =651741#73, which is also mentioned by WonderWoofy, but X server wouldn't start. I tried it again, but this time I took a look at the logs and I realized that the fix listed in the bug report has two Identifier lines, causing X server to not start. I removed the Card0 line and X started fine and I was able to control the backlight. I'll add this information to the bug report.

Thanks for the help.

Last edited by gsingh93 (2013-07-23 16:03:03)

WonderWoofy · 2013-07-23 19:04:35

It seems that someone took out all the relevant parts of that tip about 20-intel.conf on the Intel wiki page, leaving only one line. So I reverted the changes. I felt that this was a poor edit since the rest of the file in the example is not actually shipped with the xf86-video-intel package. So there was no real explanation about what the user actually needed to do.

BlaXpirit · 2014-02-05 15:38:59

Thank you, WonderWoofy. That tip worked for me.
And it seems cleaner than the kernel flags. Or am I missing something?

Arch Linux

#1 2013-07-22 17:18:50

[SOLVED] Backlight keys not working

#2 2013-07-22 17:27:44

Re: [SOLVED] Backlight keys not working

#3 2013-07-23 04:09:33

Re: [SOLVED] Backlight keys not working

#4 2013-07-23 04:38:14

Re: [SOLVED] Backlight keys not working

#5 2013-07-23 16:02:23

Re: [SOLVED] Backlight keys not working

#6 2013-07-23 19:04:35

Re: [SOLVED] Backlight keys not working

#7 2014-02-05 15:38:59

Re: [SOLVED] Backlight keys not working

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