Comment 20 for bug 555122

I fixed the bug on my HP EliteBook 8530w. The problem was the following: HAL reported that changing the brightness was handled by hardware (which is not the case for my laptop). Thus when I pressed the brightness keys the gnome-power-manager simply showed the OSD and did not take further action. Here's what I did to resolve this:

1. Find out the vendor string used by hal:

 $ lshal | grep system.hardware.vendor

 (In my case: system.hardware.vendor = 'Hewlett-Packard' )

2. Find out the product string:

 $ lshal | grep system.hardware.product

 (In my case: system.hardware.product = 'HP EliteBook 8530w' )

3. Open /usr/share/hal/fdi/information/10freedesktop/10-laptop-panel-hardware.fdi in an editor with root privileges

4. Find the xml tag that contains the hardware vendor string

5. Add the product string ("8530w") to the list of products that do no handle the panel brightness in hardware:
 I changed the part where it says
 ...
  <match key="/org/freedesktop/Hal/devices/computer:system.hardware.product" contains_outof="4410s;4415s;4416s;Compaq 5X5">
   <!-- needed since the acpi video module reports it handle the events, but it don't work on this machines-->
   <merge key="laptop_panel.brightness_in_hardware" type="bool">false</merge>
 ...
 to
 ...
  <match key="/org/freedesktop/Hal/devices/computer:system.hardware.product" contains_outof="8530w;4410s;4415s;4416s;Compaq 5X5">
   <!-- needed since the acpi video module reports it handle the events, but it don't work on this machines-->
   <merge key="laptop_panel.brightness_in_hardware" type="bool">false</merge>
 ...

6. Reboot

Summary:
Edit /usr/share/hal/fdi/information/10freedesktop/10-laptop-panel-hardware.fdi to make sure that your laptop model is listed in a "/org/freedesktop/Hal/devices/computer:system.hardware.product" xml-tag that contains a subtag like this:
 <merge key="laptop_panel.brightness_in_hardware" type="bool">false</merge>

Hope this helps!