Fixing screen brightness on Thinkpad X201 and Ubuntu 10.10

I just tried installing Ubuntu 10.10 on my Thinkpad X201. For the most part, everything worked right away and on an SSD drive, it felt blazingly fast.

However, the screen brightness controls did not work. Some online research suggested adding acpi_osi=Linux to the kernel boot parameters and I also found a tip in the thinkpad-acpi driver documentation for how to force-enable it (over the native Linux ACPI driver).

First, edit your /etc/default/grub file to add acpi_osi=Linux and acpi_backlight=vendor arguments to GRUB_CMDLINE_LINUX_DEFAULT. It should look something like this:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor"

Then run sudo update-grub to enable the new arguments. After a reboot, my brightness controls were working.

The other thing I noted was a strange error on boot: "failed to get i915 symbols". I found a solution for that, too:

sudo -s
echo "i915" >> /etc/initramfs-tools/modules
update-initramfs -k all -u

For more general information about Linux on the Thinkpad X201, see ThinkWiki.

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  1. zebh
    Posted March 22, 2011 at 2:10 pm | Permalink

    You sir, are my hero. Thank you! :D
    Been trying to fix this issue on and off for a couple of months now. Never found out about the acpi_osi=Linux part before so I'm guessing that was my mistake.

    Anyway, thanks! No more switching to virtual console to change my brightness anymore!

  2. Posted July 25, 2011 at 10:44 pm | Permalink

    Nice try, i still using Ubuntu 9.10 on my x200si

  3. Juho
    Posted November 3, 2011 at 5:10 pm | Permalink

    Thank you, this fixed the problem!

  4. Sandro
    Posted August 8, 2012 at 5:01 am | Permalink

    Great! Thanks a lot!

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