Tuesday, January 21, 2014

Lenovo S210T - Brightness Control Keys Under Ubuntu 12.04 LTS

!!!Update!!! Upgrading to 14.04 LTS needs a small change to make the brightness control work perfectly. Read the update section below.

With the default Ubuntu 12.04 installation brightness control keys won't work. To fix this follow the steps below:

1. Open terminal (press Win key and type "terminal" and choose terminal)

2. Type the below code (you may be prompted to enter password)

gksudo gedit /etc/default/grub

3. In the grub file, edit the following line

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

to

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

4. Make sure you have not done any other change by mistake as it will mess up your booting. Save and close the file.

5. Then execute below command

sudo update-grub

6. Restart your PC

Brightness Control working after ACPI change in GRUB command line

For me this fix works well. My model is the one with CDC processor, 2GB RAM,  500GB HDD. The brightness keys work most of the times, but in some sporadic cases, it won't. It happens very rarely (may be once in 20 boots). There may be some problem with drivers or something. I will update if I find out why.(see update) For Unity 3D/Unity 2D, the keyboard brightness control works flawlessly. For LXDE, the keys won't work. But alternatively you can use the xbacklight command. Follow the below steps after doing above changes.

1. To install xbacklight

sudo apt-get install xbacklight

2. To decrease brightness

xbacklight -dec 5

3. and to increase brightness

xbacklight -inc 7

The numbers can be anything But be extra careful as it may fully reduce brightness if you give large numbers.

Update: Ubuntu 14.04 LTS (April 26th 2014)

I recently updated my laptop with Ubuntu 14.04 LTS, after which the brightness control stopped working permanently. But it just needed a small change to work. Here it is.

1. Edit black list file for modprobe

gksudo gedit /etc/modprobe.d/blacklist.conf

2. Add the following lines to it

# Added to make brightness control work
blacklist ideapad_laptop

3. Reboot

That's it! Now brightness control works perfectly every times :)


Any other comments/feedbacks/improvements are welcome! Thanks for reading.

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