[PATCH][RFC] Backlight addon for dell laptops

[David Zeuthen]

On Wed, 2007-01-03 at 22:08 +0100, Erik Andrén wrote:
> The addon currently works quite well for me but I still have the
> following issues:
> 
> 1. There seems to be something funky going on in gnome-power-manager
> while changing the brightness in battery mode. It thinks the current
> level is 7 all the time. This bug is problably related to the
> gnome-power-manager as the Power Manager Brightness Applet works correctly.
> 
> 2. Brightness turnaround speed isn't great. It's definitely an
> improvement when
> compared with the patch developed by Richard Hughes in July but when
> going from 7 (highest) to 0 (lowest) you can definitely feel the lag.
> 
> 3. No support for if you have protected you bios with a password. It's
> quite possible to workaround this issue by adding some kind of a
> mechanism throwing an exception prompting for the password. This
> problably need to be coordinated with gnome-power-manager.
> 
> The attached patch cleanly applies to current git.

Looks good, I've committed this with some configure.in changes to fixup
libsmbios detection (ugh, I so hate autotools; with a vengeance even).
These changes are in this commit

 http://gitweb.freedesktop.org/?p=hal.git;a=commitdiff;h=69353b9c50d4da892f5bdd1cd75aa587870baada


>   <device>
>     <match key="system.kernel.name" string="Linux"> 
>       <match key="smbios.system.manufacturer" string="Dell Inc.">
>         <match key="system.formfactor" string="laptop">
>            <spawn udi="/org/freedesktop/Hal/devices/dell_lcd_panel"/>
>         </match>
>       </match>
>     </match>
>   </device>

Is this this good enough? Can we somehow narrow in? Perhaps the addon
needs to test (via libsmbios?) that the hardware is actually capable of
setting backlight and if not, use some mechanism to remove the device
object....

One serious concern I have is this

> HAL_ERROR(("Could not access the dcdbas kernel module. Please make sure it is loaded"));

What does this mean? What's the dcdbas kernel module? Does libsmbios, in
particular setting the backlight, not work without a third-party kernel
module on Linux? Is that module available under the GPL? If yes, is it
upstream in Linus' kernel yet?

I've yet to test this on my two Dell laptops. They're at home.

Thanks.
 
     David