Arch Linux

wind57

Member

Registered: 2013-12-08

Posts: 2

[SOLVED] x1 carbon brightness issue

Simple question here actually, I'm on x1 carbon, fresh install.
Everything works fine, expect brigtness. The thing is, when I press Fn + up or down brigtness it changes the value only after the fifth time.
It's like I can change it only by 20% and not less or more. It works fine from command line for example with :

cat 1220 /sys/class/backlight/intel_backlight/brightness

but change it every time command line seems like too much.
I thought may be a script and re-map the Fn keys, but may be there is a simple way.

Thx,
Eugene.

Last edited by wind57 (2013-12-11 21:55:21)

toz

Member

Registered: 2011-10-28

Posts: 513

Re: [SOLVED] x1 carbon brightness issue

Have you tried the acpi_osi="!Windows 2012" kernel parameter as noted here: https://wiki.archlinux.org/index.php/Le … Brightness

WonderWoofy

Member

From: Los Gatos, CA

Registered: 2012-05-19

Posts: 8,414

Re: [SOLVED] x1 carbon brightness issue

Have you tried the acpi_osi="!Windows 2012" kernel parameter as noted here: https://wiki.archlinux.org/index.php/Le … Brightness

Interestingly, while this kernel command line argument works for me, it seems that there are a number of different fixes for Intel graphics (and win 8 machines).  So it might not necessarily be that particular one.  For example, I have seen some people use acpi_osi=""  (just blank), some who are able to specify that it is Linux, and some that need to put something in their xorg.conf (or the appropriate file in xorg.conf.d).  I think that all of these are outlined in the linked article above though.

Apparently, the problem is that windows 8 implemented a new way of handling brightness that is controlled by userspace.  So the functionality no longer handles this in the firmware layer unless specifically told to do so. 

Since this is a post about the X1 specifically, I would also like to point out that using acpi_backlight=vendor should not be used in conjunction with the thinkpad-acpi module.  You will see warnings about the journal as well as dmesg if you do.

wind57

Member

Registered: 2013-12-08

Posts: 2

Re: [SOLVED] x1 carbon brightness issue

Simply magic! Seems to solve it, thx! The thing is I am using syslinux and not grub, so my settings look like this in :

/boot/syslinux/syslinux.cfg

LABEL arch
    MENU LABEL Arch Linux
    LINUX ../vmlinuz-linux
    APPEND root=/dev/sda2 rw acpi_osi="!Windows 2012"
    INITRD ../initramfs-linux.img

Cheers,
Eugene.

WonderWoofy

Member

From: Los Gatos, CA

Registered: 2012-05-19

Posts: 8,414

Re: [SOLVED] x1 carbon brightness issue

Please mark your thread as [Solved].  This can be done by editing the first post, which will give you access to editing the title.