Bug#587014: [linux-2.6] screen brightness can't be modified on Panasonic S9

[maximilian attems <max@stro.at>]

On Thu, Jun 24, 2010 at 11:22:51PM +0900, Nicolas Limare wrote:
> Package: linux-2.6
> Severity: normal
> 
> --- Please enter the report below this line. ---
> 
> Presing the "light up" / "light down" keys doesn't modify the LCD
> screen brightness.
> Directly writing to /sys/class/backlight/panasonic/brightness has the
> same effect : nothing.
> /sys/class/backlight/panasonic/actual_brightness is modified, but the
> screen brightness isn't affected.
> 
> I tried to reboot with lenny 2.6.26-2 kernel on the same system, and
> the brightness could be changed by pressing the up/down keys, so I
> believe it is a kernel issue (but gdm couldn't properly start, so it
> is not a proper workaround).
> 
> It is a serious issue, since the screen default brightness is very
> strong and uncomfortable.
> 
> I believe it is related to
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/588983
> 
> I tried to use acpi packages from unstable, without improvement.

please use reportbug the next time this report is missing important
info, followup is possible with:
reportbug -N <bugnr>

did you try 2.6.34 from experimental, does it work there?