LCD brightness cannot be adjusted on HP ProBook 4510s

[Mitko Petkov]

Binary package hint: acpi

On newly installed Ubuntu 10.04 the brightness applet does not work at all. Neither do Fn + F7 and Fn + F8 combinations. Adjusting the brightness from System -> Preferences -> Power Management also fails.
Editing /proc/acpi/video/DGFX/LCD/brightness has the desired effect. This is a temporary solution though - the brightness is reset on reboot.
I guess the problem comes from:
acpi: /usr/bin/acpi
  Installed: 1.4-2

Ubuntu release: 10.04 LTS

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: acpi 1.4-2
ProcVersionSignature: Ubuntu 2.6.32-21.32-generic-pae 2.6.32.11+drm33.2
Uname: Linux 2.6.32-21-generic-pae i686
NonfreeKernelModules: fglrx
Architecture: i386
Date: Tue May 4 00:02:56 2010
ProcEnviron:
 LANGUAGE=en_US:en
 LANG=en_US.utf8
 SHELL=/bin/bash
SourcePackage: acpi

[Commando.UA (commando-ua)]

Same on HP Probook 4310s with ATi Radeon 4330 [Ubuntu 10.04 amd64].

This bug since Lucid, in Karmic was fine.

[Mitko Petkov (noname00-ddp)]

Despite some recent updates on acpi, the problem still remains...

[Odisseus (myroslaw-holub)]

I have the same bug. On my HP Probook 4510s Lucid fails to adjust screen brightness, Karmic works fine.

[bhuvi (bhuvanesh)]

same problem for me on lenovo G550 laptop. https://bugs.launchpad.net/ubuntu/+source/udev/+bug/530238

[Mitko Petkov (noname00-ddp)]

Well, I updated the ati driver to newer version and this seems to give results. Read this wiki for more info: http://wiki.cchtml.com/index.php/Ubuntu_Lucid_Installation_Guide