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I have a Toshiba Satellite R830 laptop with Ubuntu 12.04.1 64 bit. The Fn + F6 and Fn + F7 buttons adjust brightness until I put my laptop on sleep.

On wakeup they don't work any longer. Is there a solution or a workaround to this issue?

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2 Answers

up vote 0 down vote accepted

I found a better solution than the one selected above.

  1. Press Alt + F2 and type gksudo gedit /etc/default/grub.
  2. Find the line than starts with GRUB_CMDLINE_LINUX_DEFAULT= and modify it as follows: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor".
  3. In a terminal (ctrl + alt + T) type sudo update-grub.
  4. Reboot.

Problem solved.

More info here: https://wiki.ubuntu.com/Kernel/Debugging/Backlight

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You're adding a kernel parameter. Could you post a link, or directly describe why this is needed? –  Geoff Dec 13 '12 at 14:39
See modified answer. Not that I understand the details of it. –  To Do Dec 13 '12 at 14:43
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I had the same problem with a Toshiba Portege R935 in 12.04, and I discovered this (not so elegant) workaround:

  • as root (not with sudo but actually changing user: su root), change the value in sys/class/backlight/intel_backlight/brightness

    for instance:

    echo 2937 > /sys/class/backlight/intel_backlight/brightness

Warning: these values are not between 0 and 7 (as the ones in the other directory), but between 284 and 4539, or something like that.

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Do you have to do it every time you need to change the brightness? –  To Do Oct 5 '12 at 21:01
Well, yes, but I guess you can create a shortcut as the proposed solutions in other posts. I haven't do it yet, I'll let you know if I try. At least it's good to know where the problem is... –  mfiori Oct 6 '12 at 17:29
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