Comment 12 for bug 436702

I can confirm that, with an R519, the setpci operations work under 10.04.

Setting /proc/acpi/video/GFX0/DD03/brightness does not (it says it updates: does nothing).

xrandr doesn't work when setting the backlight to legacy:

# xrandr --output LVDS1 --set BACKLIGHT_CONTROL legacy
X Error of failed request: BadName (named color or font does not exist)
  Major opcode of failed request: 149 (RANDR)
  Minor opcode of failed request: 11 (RRQueryOutputProperty)
  Serial number of failed request: 33
  Current serial number in output stream: 33

Brightness buttons bring up the notification that brightness is changing, in the top right of the screen, but don't do anything. Nor does "Power Management Preferences".

All of this is with "acpi_osi=Linux" on my command line.