Backlight debugging as per link supplied by jpds.

Backlight control does not work, but there are entries in
/sys/class/backlight.

Debugging information collected and attached.

Testing for work around:

After reboot with only the kernel parameter acpi_backlight=vendor:

The function keys (hotkeys) have no effect (i.e do not change brightness
or cause the brightness indicator to appear) but the Brightness slider
in the Brightness & Lock settings dialogue does change the screen
brightness.

Command ls /sys/class/backlight > vendorbacklight was executed

There is a folder /sys/class/backlight/intel_backlight/

Command ls -la /sys/class/backlight/intel_backlight/ > lslabacklight was
executed

Command echo 8 > /sys/class/backlight/intel_backlight/brightness
executed causing the screen brightnes to change to very dim.


After reboot with only the kernel parameter video.use_bios_initial_backlight=0 :

The function keys (hotkeys) do not change brightness but they do cause
the brightness indicator to appear and move. The Brightness slider in
the Brightness & Lock settings dialogue *does* change the screen
brightness.


Kernel is 3.13.0-24-generic. After reboot with only the kernel parameter 
video.use_native_backlight=1 :

The function keys (hotkeys) do not change brightness but they do cause
the brightness indicator to appear and move. The Brightness slider in
the Brightness & Lock settings dialogue does not change the screen
brightness.


** Attachment added: "acpi"
   
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1311297/+attachment/4095598/+files/acpi

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https://bugs.launchpad.net/bugs/1311297

Title:
  Screen brightness cannot be adjusted on ASUS Eeepc 1015PEM

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