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I am unable to change and reduce the Screen brightness of my laptop Samsung RV520, it has only one graphics card Nvidia's GT520M, although brightness control appears by pressing

FN+UP/DOWN

However nothing happens,

I tried both options usually mentioned online i.e.

  1. Changing Grub and adding apci=vendor option but the control bar of brightness disappeared but still I was unable to control the brightness.

  2. I also installed Samsung's backlight tool but still no avail

What should I do kindly guide! I am using Ubuntu 12.04 x64 and Nvidia's drivers are installed and are working

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2 Answers 2

Try to use the recommendations from this link. Brightness works on my RV 520, with some issues though.

http://www.voria.org/forum/viewtopic.php?f=3&t=1040

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From the article Sergey susggested here are the detailed that linux-man worked out. I can't test it since I don't have a Samsung computer and I suspect that it might better refer to older versions of Ubuntu. Good luck with it. That article was here.

You should first backup and of the files you will be changing in case they make things work rather than better.

  1. Open a terminal with Alt-Ctrl-t
  2. `gksudo gedit /etc/modprobe.d/intel_ips.conf
  3. Enter the following line into that file: "blacklist intel_ips" and save the file.
  4. If you have a file /etc/modprobe.d/samsung-blacklight.conf run your editor on it as above and add # from the line that says #samsung-laptop. Make sure the following line contains "use_sabi 1" rather than "use_sabi 0".
  5. Enter gksudo gedit /etc/default/grub
  6. Change the GRUB_CMDLINE_LINUX= value to acpi_sleep=nonvs,acpi_backlight=vendor,pcie_aspm=force

  7. Save the file, exit the editor and then run: sudo update-grub

  8. Install the following by clicking on the bag fglrx-updatesInstall fglrx-updates, it appears this may or may not be necessary.

The first four steps tell Linux kernel to swap the driver it will use to manage part of your hardware. The grub steps (5, 6 and 7) give the kernel additional instructions every time you boot. You can ignore grub for now and tell it to do this manually if you prefer to do that as a test. I'm not sure where "fglrx-updates come in". The importance of use_sabi=1 was determined later in the same forum thread.

I hope this helps somehow and good luck. Thanks go to Sergey, linux-man, and Kweck.

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Let me try it out I hope everything goes fine else! My Ubuntu will be ruined its such a rich experience! But the brightness doesn't let me work longer –  aibk01 Sep 13 '12 at 17:56

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