Screen brightness does not function on Acer Aspire Timeline series

[executorvs]

Binary package hint: gnome-power-manager

I'm running Karmic from a fresh install with all current updates as of 11:30PM central standard in the US 9/28/09.
this problem is present in Jaunty as well.
my computer is an acer aspire timeline 5810TZ-4274.

using FN+left arrow or FN+right arrow activates notify-OSD indicator but has no actual effect on brightness.
adding screen brightness applet makes no difference.

ProblemType: Bug
Architecture: i386
Date: Tue Sep 29 00:17:41 2009
DistroRelease: Ubuntu 9.10
Package: gnome-power-manager 2.28.0-0ubuntu1
ProcEnviron:
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.31-11.36-generic
SourcePackage: gnome-power-manager
Uname: Linux 2.6.31-11-generic i686

[Emiel Kollof (emiel-kollof)]

I found something interesting that might help resolve this. I was updating my karmic on my T5810, and AIGLX somehow broke. So it came up without any hardware 3d acceleration at all, but the brightness applet and keys worked!

[Emiel Kollof (emiel-kollof)]

Found a workaround for the 5810T:

Add the following to the GRUB_CMD_LINUX_DEFAULT entry in /etc/default/grub: acpi_backlight=vendor

[Emiel Kollof (emiel-kollof)]

Oh, and it seems above solution works best if KMS is disabled.

[trendzetter (trendzetter)]

Adding GRUB_CMDLINE_LINUX="nomodeset acpi_backlight=vendor" in /etc/default/grub and running update-grub works as a workaround for me too.

[executorvs (executorvs)]

after current updates and using current kernel 2.6.31-12-generic still does not function out of box.

[Matti Viljanen (direc85)]

Same here, backlight doesn't work with Acer Aspire 2920 w/ Intel 965GM