Brightness issue on Samsung Ativ Book 6

[gls]

I recently installed Ubuntu 14.04 on my Samsung Ativ Book 6 (NP680Z5E-X01US).

Since then I am completely unable to modify my brightness settings. The Fn buttons work fine, if I press Fn+F2/F3 I can see the brightness slider, but no change happens until I push it down to where it deactivates the screen. Also, there is no response from the keyboard backlight. Other work fine (audio, wifi, mousepad-lock)

I have tried several options and I am essentialy in the same spot of the user here:

http://askubuntu.com/questions/70552/ca ... ptop?rq=1
What I tried:

- Edit /etc/default/grub ↦ GRUB_CMDLINE_LINUX_DEFAULT: acpi_osi=Linux,
acpi_backlight=vendor (as well as several different combinations of
these settings being on or off)

- Edit /etc/X11/xorg.conf (file doesn't exist on my system)


- sudo setpci -s 00:02.0 F4.B=XX (does nothing)

- xbacklight -set XX (does nothing)

- install indicator-brightness (changing its value does nothing)

Checking the folder

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    ls /sys/class/backlight/intel_backlight/

shows that

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    max_brightness = 4882

while

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    actual_brightness
    brightness

change as I move the slider in step of 244, but no corresponding change in brightness happens.

My graphic card is

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    00:02.0 VGA compatible controller [0300]: Intel Corporation 3rd Gen Core processor Graphics Controller [8086:0166] (rev 09)     

I also have a Radeon

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    01:00.0 Display controller: Advanced Micro Devices, Inc. [AMD/ATI] Mars [Radeon HD 8670A/8670M/8750M] (rev ff)

Can somebody please help or offer suggestion on where to look next?