Arch Linux

eDio

Member

From: Ukraine, Kyiv

Registered: 2008-12-02

Posts: 422

[SOLVED] Broken backlight brightness adjustment on x220 after recent…

Hi.

I'm no longer able to adjust backlight brightness with hotkeys and xbacklight.
I believe issue appeared after update to linux-3.16.

Brightness adjustment keys are detected correctly in xev.
Echoing brightness value to /sys/class/backlight/intel_backlight/brightness does adjust brightness.

But xbacklight and hotkeys won't do a thing.

I already tried some magic I don't understand: acpi_backlight=vendor and acpi_osi=linux. No luck here.

Anyone else with the same issue? Are there any fixes for this?

Thanks in advance.
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Solution (thanks, heimer16):
https://bbs.archlinux.org/viewtopic.php … 3#p1448253

Last edited by eDio (2014-08-18 23:27:52)

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github.com/edio

mentat

Member

From: France

Registered: 2009-01-13

Posts: 138

Website

Re: [SOLVED] Broken backlight brightness adjustment on x220 after recent…

Hi,
same issue here with X220.

check in boot log, I've mutliple lines:

ACPI group/action undefined: video/brightnessdown / BRTDN

EDIT:
Sure it'll be fix with script like this one:
https://wiki.archlinux.org/index.php/AC … ht_control

But need to find or wait the patch for an 'out the box' solution before.

Last edited by mentat (2014-08-18 09:08:09)

emak

Member

Registered: 2012-03-20

Posts: 32

Re: [SOLVED] Broken backlight brightness adjustment on x220 after recent…

Hi there

Same issue with a Clewo W740SU / Tuxedo BU1402. I used the workaround with code below in grub.cfg which worked flawlessly till last kernel update:

        acpi_osi=Linux
        acpi_backlight=vendor

heimer16

Member

Registered: 2012-03-15

Posts: 20

Re: [SOLVED] Broken backlight brightness adjustment on x220 after recent…

I had the same issue here.

I saw a brief mention in the arch wiki: https://wiki.archlinux.org/index.php/Backlight
that says the kernel parameter: video.use_native_backlight=1 is now default in 3.16,

so I added video.use_native_backlight=0 to my kernel parameters and my backlight functionality is back.

klz

Member

Registered: 2011-02-14

Posts: 23

Re: [SOLVED] Broken backlight brightness adjustment on x220 after recent…

I had the same issue here.

I saw a brief mention in the arch wiki: https://wiki.archlinux.org/index.php/Backlight
that says the kernel parameter: video.use_native_backlight=1 is now default in 3.16,

so I added video.use_native_backlight=0 to my kernel parameters and my backlight functionality is back.

awesome thx, worked for me as well. I used the -u option of efibootmgr

efibootmgr -c -d /dev/sda -p 1 -L Gentoo3.16.3-rev1 -l "\efi\boot\kernel_3.16.3-rev1.efi" -u "video.use_native_backlight=0"