screen brightness controls don't work

Asked by mukesh agrawal

With the latest kernel from ubuntu, my system no longer responds to screen brightness adjustments. The OSD shows that the keyevents for brightness up and brightness down are received. (The brightness indicator is displayed, and the bar moves left or right as I would expect, based on the key pressed.) However, the LCD's backlight does not dim/brighten.

system: lenovo thinkpad x61
$ uname -a
Linux discipline 2.6.27-11-generic #1 SMP Thu Jan 29 19:24:39 UTC 2009 i686 GNU/Linux

Package status for latest kernel package:

$ dpkg --status linux-image-2.6.27-11-generic
Package: linux-image-2.6.27-11-generic
Status: install ok installed
Priority: optional
Section: base
Installed-Size: 92184
Maintainer: Ubuntu Kernel Team <email address hidden>
Architecture: i386
Source: linux
Version: 2.6.27-11.27
Provides: fuse-module, ivtv-modules, kvm-api-4, linux-image, linux-image-2.6, ndiswrapper-modules-1.9, redhat-cluster-modules
Depends: initramfs-tools (>= 0.36ubuntu6), coreutils | fileutils (>= 4.0), module-init-tools (>= 3.3-pre11-4ubuntu3)
Pre-Depends: dpkg (>= 1.10.24)
Recommends: lilo (>= 19.1) | grub
Suggests: fdutils, linux-doc-2.6.27 | linux-source-2.6.27
Conflicts: hotplug (<< 0.0.20040105-1)
Description: Linux kernel image for version 2.6.27 on x86/x86_64
 This package contains the Linux kernel image for version 2.6.27 on
 x86/x86_64.
 .
 Also includes the corresponding System.map file, the modules built by the
 packager, and scripts that try to ensure that the system is not left in an
 unbootable state after an update.
 .
 Supports Generic processors.
 .
 Geared toward desktop systems.
 .
 You likely do not want to install this package directly. Instead, install
 the linux-generic meta-package, which will ensure that upgrades work
 correctly, and that supporting packages are also installed.

Previous kernel package status:

$ dpkg --status linux-image-2.6.27-9-generic
Package: linux-image-2.6.27-9-generic
Status: install ok installed
Priority: optional
Section: base
Installed-Size: 92124
Maintainer: Ubuntu Kernel Team <email address hidden>
Architecture: i386
Source: linux
Version: 2.6.27-9.19
Provides: fuse-module, ivtv-modules, kvm-api-4, linux-image, linux-image-2.6, ndiswrapper-modules-1.9, redhat-cluster-modules
Depends: initramfs-tools (>= 0.36ubuntu6), coreutils | fileutils (>= 4.0), module-init-tools (>= 3.3-pre11-4ubuntu3)
Pre-Depends: dpkg (>= 1.10.24)
Recommends: lilo (>= 19.1) | grub
Suggests: fdutils, linux-doc-2.6.27 | linux-source-2.6.27
Conflicts: hotplug (<< 0.0.20040105-1)
Description: Linux kernel image for version 2.6.27 on x86/x86_64
 This package contains the Linux kernel image for version 2.6.27 on
 x86/x86_64.
 .
 Also includes the corresponding System.map file, the modules built by the
 packager, and scripts that try to ensure that the system is not left in an
 unbootable state after an update.
 .
 Supports Generic processors.
 .
 Geared toward desktop systems.
 .
 You likely do not want to install this package directly. Instead, install
 the linux-generic meta-package, which will ensure that upgrades work
 correctly, and that supporting packages are also installed.

Question information

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marcobra (Marco Braida) (marcobra) said :
#1

Please try to add this line to my /etc/Xorg/xorg.conf

    Option "RegistryDwords" "EnableBrightnessControl=1"

in Section "device"

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