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#1 2013-03-14 21:13:14

Registered: 2013-01-29
Posts: 13

[SOLVED] Backlight control only over radeon_bl0?


I installed ArchLinux on my iMac 12.1 today and everything seems to work like a charm. I am using the OpenSource radeon-driver which work well (Radeon HD 6770M).

The Fn-Keys setting the backlight via


but this does not work. The thing is that I can change the backlight via

echo 10 > /sys/class/backlight/radeon_bl0/brightness

and this works.

What can I do now, to get the Fn-Keys working? Can I change the behaviour of the Fn-Keys or can I fix the acpi_video0 part?


Haha, right after the post I found the solution... xD

I added "acpi_backlight=vendor" to my kernel boot parameters....

Last edited by -MacNuke- (2013-03-14 21:32:40)


#2 2015-08-01 12:24:54

Registered: 2015-08-01
Posts: 1

Re: [SOLVED] Backlight control only over radeon_bl0?


don't know how to thank you enough. Now I can dim my screen so low that even smartphones can't do.

I tried echo 1 > and, even in the darkest environment, it's so dimmed that it barely emitted the light and barely was able to be seen, lol.


#3 2015-08-01 13:51:52

Registered: 2014-03-03
Posts: 146

Re: [SOLVED] Backlight control only over radeon_bl0?

If it doesn't work out of the box, then you should fill in a kernel bug report. Workarounds like acpi_backlight=vendor are not normally meant to be used.


#4 2015-08-01 19:52:03

Forum Moderator
From: Scotland
Registered: 2010-06-16
Posts: 5,703

Re: [SOLVED] Backlight control only over radeon_bl0?

Grit, welcome to the Arch Linux forums. Please take a moment to read through the forum etiquette; particularly the section regarding old threads and necrobumping.


Mobo: ASUS P8Z77-V PRO // Processor: Intel Core i7-3770K 3.4GHz // GFX: nVidia GeForce GTX 970 Ti // RAM: 32GB (4x 8GB) Corsair DDR3 (@ 2133MHz) // Storage: 1x 3TB Seagate SATAII 5x 1TB Samsung SATAII, 2x 120GB Corsair SSD

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