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Thread: Macbook Pro Adjust Backlight and Brightness Defaults

  1. #1
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    Macbook Pro Adjust Backlight and Brightness Defaults

    I installed 12.04 on my Macbook Pro 8,2 and am having trouble finding a way to adjust the keyboard backlight and screen brightness defaults. On boot the welcome screen always shows both at full brightness and doesn't allow me to change either with keyboard shortcuts. After I log in I am able to change the settings to a more comfortable level using the keyboard shortcuts but these settings are promptly erased when I reboot, defaulting back to the annoying full brightness/backlight when I log in again. How can I adjust these defaults? Is there a way to make Ubuntu remember my last setting for the next time I log in?

  2. #2
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    Re: Macbook Pro Adjust Backlight and Brightness Defaults

    I am not familiar with Macbooks so I can't tell you for sure. Macbooks does have BIOS or not? If they have check that in Bios. At least on the regular computer I solve my problem with Bios.

    I DON'T EVEN KNOW WHAT A QUANTAL QUETZAL IS...BUT IT SOUNDS LIKE PRETZEL AND I LIKE PRETZEL

  3. #3
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    Re: Macbook Pro Adjust Backlight and Brightness Defaults

    I believe MacBooks use EFI (or at least new ones do, and I have a new one) because EFI is used with the new Intel technology Apple started using in 2006. However, according to Wiki (http://en.wikipedia.org/wiki/Unified...ing_EFI.2FUEFI), Macs still have BIOS compatibility because of a firmware update. Does that help? I'm pretty new to all this EFI/BIOS stuff so I'm just writing stuff I learned about five minutes ago.

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    Re: Macbook Pro Adjust Backlight and Brightness Defaults

    I don't know what Macbook has, definitely some kind of Bios. On normal computer if you hold delete (some laptops f2) during the boot up you are prompted to Bios screen, where you can adjust default brightnes. Try different keys and you will see.

    I DON'T EVEN KNOW WHAT A QUANTAL QUETZAL IS...BUT IT SOUNDS LIKE PRETZEL AND I LIKE PRETZEL

  5. #5
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    Re: Macbook Pro Adjust Backlight and Brightness Defaults

    Will that work for the keyboard backlight too? And isn't there a way to control it with the GUI? Mac OS had no problem keeping my old settings when I logged in...

  6. #6
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    Re: Macbook Pro Adjust Backlight and Brightness Defaults

    If you edit your /etc/rc.local file you can add a couple lines to set screen and keyboard brightness which is run shortly after boot.

    Code:
    echo '5' > /sys/devices/pci0000:00/0000:00:02.0/backlight/acpi_video0/brightness
    ## this adjusts the screen backlight, the values range from 1 to 15.
    
    echo '25' > /sys/devices/platform/applesmc.768/leds/smc::kbd_backlight/brightness
    ## this adjusts the keyboard brightness and ranges from 1 to 255.
    Those are the two lines I use. I have a macbook 8,1.

    Source: http://ubuntuforums.org/archive/inde...t-1010532.html

    You can adjust screen brightness with the gui.

    System settings > brightness and lock.

    I'm not sure if you can change the keyboard backlight with the gui.

    I don't think Ubuntu remembers the brightness setting on macbooks. Remember that they are different operating systems. Just because OS X behaves one way doesn't mean that Ubuntu has to.

    Kopkins
    Last edited by Kopkins; July 9th, 2012 at 05:17 PM.

  7. #7
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    Re: Macbook Pro Adjust Backlight and Brightness Defaults

    I have the same issue that the OP described, except I am on a Macbook Pro version 6,2 (mid-2010 model). I was able to set the screen and keyboard backlight ranges using the instructions here. I also added
    Code:
    echo X > /sys/devices/virtual/backlight/apple_backlight/subsystem/gmux_backlight/brightness
    with different values for X into /etc/rc.local, but still when I resume from a suspended computer, or a fresh boot, my retinas burn with the fury that is a max brightness screen. I feel like I am very close to having this solved, but am stuck. Has anyone had any luck with this? Anyone know why my echo X line may not be working?

  8. #8
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    Re: Macbook Pro Adjust Backlight and Brightness Defaults

    Quote Originally Posted by stefprez View Post
    I have the same issue that the OP described, except I am on a Macbook Pro version 6,2 (mid-2010 model). I was able to set the screen and keyboard backlight ranges using the instructions here. I also added
    Code:
    echo X > /sys/devices/virtual/backlight/apple_backlight/subsystem/gmux_backlight/brightness
    with different values for X into /etc/rc.local, but still when I resume from a suspended computer, or a fresh boot, my retinas burn with the fury that is a max brightness screen. I feel like I am very close to having this solved, but am stuck. Has anyone had any luck with this? Anyone know why my echo X line may not be working?
    Can you post your rc.local?

    Also please post any output of the following:
    One command per line. Use whatever value you have substituted for X.
    Code:
    sudo su
    echo X > /sys/devices/virtual/backlight/apple_backlight/subsystem/gmux_backlight/brightness
    exit
    Thanks,
    Kopkins

  9. #9
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    Re: Macbook Pro Adjust Backlight and Brightness Defaults

    Quote Originally Posted by Kopkins View Post
    Can you post your rc.local?

    Also please post any output of the following:
    One command per line. Use whatever value you have substituted for X.
    Code:
    sudo su
    echo X > /sys/devices/virtual/backlight/apple_backlight/subsystem/gmux_backlight/brightness
    exit
    Thanks,
    Kopkins
    Sorry for the long delay! Here's my rc.local.

    Code:
    #$backlight_brightness range  0-82311
    echo $backlight_brightness > /sys/devices/virtual/backlight/apple_backlight/subsystem/gmux_backlight/brightness
    
    #$kbd_brightness range 0-255
    echo $kbd_brightness > /sys/class/leds/smc\:\:kbd_backlight/brightness
    
    echo 4 > /sys/devices/virtual/backlight/apple_backlight/subsystem/gmux_backlight/brightness
    
    exit 0
    When I enter "4" for X on the command you supplied, it dims my screen to almost off, which is what I would expect, however the rc.local doesn't seem to be doing this on boot or wake from sleep. Do I need to include a sudo su command or something in rc.local? Is there another reason why the screen is still defaulting to 1000 suns brightness possibly? Thanks for the help so far!

  10. #10
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    Re: Macbook Pro Adjust Backlight and Brightness Defaults

    Quote Originally Posted by cismohit View Post
    there is no such way yet..for last setting for the next time log in..plz reinstall it again
    Reinstall what? Ubuntu? That's supposed to solve the problem?

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