Sunday, April 29, 2012

Fix: Screen Brightness Resets To Lowest Level On Ubuntu 12.04 Startup


Recently I have just installed the Ubuntu 12.04 Precise Pangolin on my HP mini 210. The first problem I noticed was my netbook's display brightness is at the lowest level. I increase the display brightness to my preferred brightness level using keyboard shortcuts and 'Brightness and Lock' in Ubuntu system settings but the screen brightness will still resets to the lowest level everytime I start/restart the netbook.

If your laptop or netbook having same scenario as mine, here's how to fix it:

  1. Edit the 'rc.local' file. In terminal:
    2. gksu gedit /etc/rc.local

  2. Add the code below into the file, before the line exit 0:
    3. echo 7 > /sys/class/backlight/acpi_video0/brightness

    The number 7 represents the display brightness level you want. Save and close this file.

    The range of brightness level is different on different computers. You can check the maximum brightness level for your computer via this path: /sys/class/backlight/acpi_video0/max_brightness. For my HP mini 210, the max brightness is 10. So this means the range of brightness level for my netbook is from 0 to 10.
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22 comments:

  1. Art VandelayMay 1, 2012 at 1:57 AM

    It works on a Dell Inspiron. Thanks, dude!

    ReplyDelete
  2. LemonMay 1, 2012 at 2:03 AM

    You're welcome. Appreciate your feedback.

    ReplyDelete
  3. uilianMay 2, 2012 at 5:57 AM

    With little changes, it worked on my Sony Vaio too:

    echo 7 > /sys/class/backlight/sony/brightness 

    Thanks!

    ReplyDelete
  4. LemonMay 2, 2012 at 5:23 PM

    Thank you! It will be very helpful for other Sony laptop owners.

    ReplyDelete
  5. cmcanultyMay 5, 2012 at 8:39 PM

    doesn't work on HP G72t a kernel patch fixed it in 11.10 now it is back. Very aggravating.

    ReplyDelete
  6. LemonMay 6, 2012 at 1:31 AM

    Understood how irritating it could be.

    What folders do you have in /sys/class/backlight ?

    ReplyDelete
  7. cmcanultyMay 6, 2012 at 9:15 PM

     acpi_video0 and intel_backlight thank you

    ReplyDelete
  8. Pedro MarinhoMay 7, 2012 at 9:05 AM

    I was having exactly the same problem. Your solution was very helpful! Thank you very much!

    ReplyDelete
  9. LemonMay 7, 2012 at 5:43 PM

    We have same folders in /sys/class/backlight so I have no idea. Wish I could help.

    ReplyDelete
  10. LemonMay 7, 2012 at 5:44 PM

    No problem. Thanks for the nice feedback.

    ReplyDelete
  11. Alan LokMay 9, 2012 at 10:33 PM

    Thank you so much for the fix. This worked on Asus A42J series.

    ReplyDelete
  12. cmcanultyMay 10, 2012 at 12:09 AM

    I got a fix for my system here
    http://ubuntuforums.org/showthread.php?t=1972303&highlight=screen+Brightness+ste+0%25

    ReplyDelete
  13. LemonMay 10, 2012 at 4:13 PM

    Thanks for the feedback. :)

    ReplyDelete
  14. LemonMay 10, 2012 at 4:15 PM

    Thanks for the heads up. It is very helpful.

    ReplyDelete
  15. cmcanultyMay 10, 2012 at 8:04 PM

     this worked for me
    http://ubuntuforums.org/showthread.php?t=1972303&highlight=screen+Brightness+ste+0%25

    ReplyDelete
  16. Amit RajAugust 15, 2012 at 2:32 AM

    thnks a lot..really helpful :)

    ReplyDelete
  17. MokAugust 19, 2012 at 3:48 PM

    You're welcome. Thank you for stopping by and commenting. :)

    ReplyDelete
  18. WilOctober 26, 2012 at 4:34 AM

    Hi, thanks for the tips but I got a permission denied if I just echo this code.
    I've to do this: "sudo su && echo 10 > /sys/class/backlight/acpi_video0/brightness" and then enter my password to make it work. What should I do to avoid this ?
    thank you.

    ReplyDelete
  19. MokOctober 26, 2012 at 2:51 PM

    It will also prompt me to enter my password for root privilege when I use gksu. I would recommend to use gksu for graphical applications and sudo for command-line applications.

    ReplyDelete
  20. Linux-pisserMarch 19, 2013 at 8:47 PM

    This doesn't work on Asus U31SD-XH51.

    ReplyDelete
  21. ShizunJune 3, 2013 at 2:12 AM

    It worked for HP ProBook 4330s.

    OS: Linux Mint Maya 13

    ☆ Thank you! ☆

    ReplyDelete
  22. MokJune 9, 2013 at 10:10 AM

    Glad it helps.

    ReplyDelete

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