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Thread: help : brightness control

  1. #1
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    help : brightness control

    hi,,

    i am using xubuntu 11.10 in samsung mini n148 laptop.. how to control brightness ...default key fn + down arrow not control the brightness ... please help...

    thank u

  2. #2
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    Re: help : brightness control

    Hi

    Please post the output of

    Code:
    ls /sys/class/backlight
    Kind regards
    If you believe everything you read, you better not read. ~ Japanese Proverb

    If you don't read the newspaper, you're uninformed. If you read the newspaper, you're mis-informed. - Mark Twain

  3. #3
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    Re: help : brightness control

    desktop@ubuntu:/etc/default$ ls /sys/class/backlight

    acpi_video0 intel_backlight




    Quote Originally Posted by matt_symes View Post
    Hi

    Please post the output of

    Code:
    ls /sys/class/backlight
    Kind regards

  4. #4
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    Re: help : brightness control

    Hi

    Quote Originally Posted by dsuresh View Post
    desktop@ubuntu:/etc/default$ ls /sys/class/backlight

    acpi_video0 intel_backlight
    Interesting. You have two entries. Let's see which one works (if either).

    From the terminal type

    Code:
    sudo bash -c "echo 2 > /sys/class/backlight/acpi_video0/brightness"
    Does that darken the screen ? If not try

    Code:
    sudo bash -c "echo 2 > /sys/class/backlight/intel_backlight/brightness"
    Does that darken the screen ?

    If the screen is darkened then type

    Code:
    sudo bash -c "echo 9 > /sys/class/backlight/ZZZZ/brightness"
    and replace ZZZZ with which ever one darkened the screen.

    Post back results.

    EDIT: I have to pop out for a couple of hours. If no one else picks this up i will continue it later.

    Kind regards
    Last edited by matt_symes; October 21st, 2011 at 12:46 PM.
    If you believe everything you read, you better not read. ~ Japanese Proverb

    If you don't read the newspaper, you're uninformed. If you read the newspaper, you're mis-informed. - Mark Twain

  5. #5
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    Re: help : brightness control

    this command working :

    sudo bash -c "echo 2 > /sys/class/backlight/intel_backlight/brightness"

    ...

  6. #6
    Join Date
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    Re: help : brightness control

    Hi

    Quote Originally Posted by dsuresh View Post
    this command working :

    sudo bash -c "echo 2 > /sys/class/backlight/intel_backlight/brightness"

    ...
    Can you post the output of

    Code:
    cat /proc/cmdline
    It may help to resolve why you have two entries.

    So we need to remove acpi_video0. Open a terminal and type

    Code:
    sudo modprobe -r video
    Check your brightness buttons again.

    Post back the results.

    This will not persist after a reboot so, if it works, we can look at making it permanent.

    Kind regards
    If you believe everything you read, you better not read. ~ Japanese Proverb

    If you don't read the newspaper, you're uninformed. If you read the newspaper, you're mis-informed. - Mark Twain

  7. #7
    Join Date
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    Re: help : brightness control

    desktop@ubuntu:~$ cat /proc/cmdline

    BOOT_IMAGE=/boot/vmlinuz-3.0.0-12-generic root=UUID=be5daad2-0aa9-49ca-b2e3-aae1cca3bee6 ro quiet splash vt.handoff=7


    desktop@ubuntu:~$ sudo modprobe -r video
    [sudo] password for desktop:
    FATAL: Module video is in use.

  8. #8
    Join Date
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    Re: help : brightness control

    Hi
    Quote Originally Posted by dsuresh View Post
    desktop@ubuntu:~$ cat /proc/cmdline

    BOOT_IMAGE=/boot/vmlinuz-3.0.0-12-generic root=UUID=be5daad2-0aa9-49ca-b2e3-aae1cca3bee6 ro quiet splash vt.handoff=7
    Nothing wrong with this command line.

    desktop@ubuntu:~$ sudo modprobe -r video
    [sudo] password for desktop:
    FATAL: Module video is in use.
    This is interesting and may be the reason why you have two entries.

    Let's try to blacklist it and reboot.

    From the terminal...

    Code:
    sudo bash -c "echo 'blacklist video' >> /etc/modprobe.d/blacklist.conf"
    Code:
    sudo reboot
    Post back.

    Kind regards
    If you believe everything you read, you better not read. ~ Japanese Proverb

    If you don't read the newspaper, you're uninformed. If you read the newspaper, you're mis-informed. - Mark Twain

  9. #9
    Join Date
    Nov 2007
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    12

    Re: help : brightness control

    no.its not working....

  10. #10
    Join Date
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    Re: help : brightness control

    Hi

    The good thing is we know what the problem is. We just need to work out how to fix it.

    Let's try to force it to use Intels version. Open a terminal and type

    Code:
    sudo nano /etc/default/grub
    Look for the two line that say

    Code:
    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
    GRUB_CMDLINE_LINUX=""
    and edit them so they say

    Code:
    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"
    GRUB_CMDLINE_LINUX="acpi_backlight=vendor"
    Press ctrl + o to save and ctrl + x to exit.

    Then type

    Code:
    sudo update-grub
    Reboot your PC and try again.

    Post back the results of

    Code:
    cat /proc/cmdline
    and

    Code:
    ls /sys/class/backlight
    after making the above changes.

    Kind regards
    Last edited by matt_symes; October 22nd, 2011 at 02:20 PM.
    If you believe everything you read, you better not read. ~ Japanese Proverb

    If you don't read the newspaper, you're uninformed. If you read the newspaper, you're mis-informed. - Mark Twain

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