Bug 68394

Summary: KDE 4 with xf8x-video-intel 2.21.14 can't set the brightness.
Product: xorg Reporter: Alexander Kaltsas <alexkaltsas>
Component: Driver/intelAssignee: Chris Wilson <chris>
Status: RESOLVED NOTOURBUG QA Contact: Intel GFX Bugs mailing list <intel-gfx-bugs>
Severity: normal    
Priority: medium    
Version: 7.7 (2012.06)   
Hardware: x86 (IA32)   
OS: Linux (All)   
See Also: https://bugs.freedesktop.org/show_bug.cgi?id=71493
i915 platform: i915 features:
Description Flags
Xorg log, Vbios dump, Xrandr output, Intel reg dump files. none

Description Alexander Kaltsas 2013-08-21 18:21:09 UTC
Created attachment 84406 [details]
Xorg log, Vbios dump, Xrandr output, Intel reg dump files.

After upgrading to xf86-video-intel to 2.21.14 KDE can no longer control the brightness. It display the brightness level info, but no change. Downgrading to 2.21.13 solves the issue.

issuing as root:

echo _value_ > /sys/class/backlight/intel_backlight/brightness

changes the brightness.

_value_: 0 to 4882

Extra info: http://forum.kde.org/viewtopic.php?f=225&t=117153

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

kernel driver: i915

uname -r: 3.10.7-1-ARCH
uname -m: i686
xf86-video-intel: 2.21.14
Xorg -version: X.Org X Server 1.14.2, Release Date: 2013-06-25
mesa: 9.1.6
libdrm: 2.4.46
Distro: Arch Linux
Display: LVDS

Laptop model: Dell Inspiron 411z-6733
Comment 1 Chris Wilson 2013-08-21 20:55:27 UTC
The dell_backlight interface is dysfunctional and should not be exposed for your system i.e. don't specify acpi_backlight=vendor. Also i915.i915_enable_fbc=1 is known to cause issues on your system.
Comment 2 Alexander Kaltsas 2013-08-22 08:11:50 UTC
Thanks you for your answer. 

Any suggestions? Bug report for another packet? Stay with xf86-video-intel 2.21.13?

Reoving acpi_backlight=vendor make the brightness control very erratic.
Comment 3 Chris Wilson 2013-08-22 09:43:41 UTC
You can use Option "backlight" "intel_backlight" to override the selection of dell_backlight.
Comment 4 Alexander Kaltsas 2013-08-22 10:01:21 UTC
Thanks you!

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