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Thread: Brightness Adjustment PRoblem

  1. #1
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    Brightness Adjustment PRoblem

    I have Intel Imac 11,3 (27" LED, purchased in 2009) with Radeon HD 5750 graphic card. When I installed Ubuntu 12.04 LTS, everything works fine except brigthness control. I want to mention that I didn't install any additional driver.

    I tried "sudo update-grub" after changing /etc/default/grub by acpi_backlight=vendor with/without acpi_osi=Linux. Nothing changes.

    What can I do to fix this issue?

  2. #2
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    Re: Brightness Adjustment PRoblem

    Quote Originally Posted by carkaci View Post
    I have Intel Imac 11,3 (27" LED, purchased in 2009) with Radeon HD 5750 graphic card. When I installed Ubuntu 12.04 LTS, everything works fine except brigthness control. I want to mention that I didn't install any additional driver.

    I tried "sudo update-grub" after changing /etc/default/grub by acpi_backlight=vendor with/without acpi_osi=Linux. Nothing changes.

    What can I do to fix this issue?
    If you go to a terminal session <cntrl-alt-T> or to a command prompt <cntrl-alt-F2> (then log in) can you:
    Code:
    setpci -s 00:02.0 F4.B=00
    --OR--
    While in a session try <function-right arrow> or <function-left arrow>, does it vary your brightness settings?
    Last edited by MAFoElffen; February 3rd, 2013 at 10:23 PM.
    Multi-Boot= Various flavours of Windows, Linux and Unix... Ubuntu user # 33563, Linux user # 533637
    Sticky: [all variants] Graphics Resolution- Upgrade /Blank Screen after reboot
    Boot Info Script courtesy of community member meierfra

  3. #3
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    Re: Brightness Adjustment PRoblem

    I tried
    setpci -s 00:02.0 F4.B=00

    Here is the result
    setpci: Warning: No devices selected for "F4.B=00"

    I cannot try function-right/left arrow because, I use Microsoft Wireless Keyboard rather than Imac's default.

    (Note: Excuse me, my machine was pucheased in 2011, not in 2009)
    Last edited by carkaci; February 3rd, 2013 at 10:38 PM.

  4. #4
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    Re: Brightness Adjustment PRoblem

    Ipad... Okay

    Please post the results of
    Code:
    lspci | grep VGA
    That will tell us the video info.

    Then
    Code:
    ls /sys/class/backlight/*
    Look for any directory name that resembles the video you have.

    Then
    Code:
    echo -n 50 | sudo tee /sys/class/backlight/video_name/brightness
    Where the variable "n", substitute 0 to 127.
    0 should be the brightest setting.
    At variable "video_name" substitute the directory name.

    If that works, play with "n" until you find a usable brightness setting. Post what that setting is and I'll tell you what to change to make that setting resident on bootup.
    Last edited by MAFoElffen; February 3rd, 2013 at 11:41 PM.
    Multi-Boot= Various flavours of Windows, Linux and Unix... Ubuntu user # 33563, Linux user # 533637
    Sticky: [all variants] Graphics Resolution- Upgrade /Blank Screen after reboot
    Boot Info Script courtesy of community member meierfra

  5. #5
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    Re: Brightness Adjustment PRoblem

    >lspci | grep VGA

    01:00.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI Broadway PRO [Mobility Radeon HD 5800 Series]

    >ls /sys/class/backlight/*

    actual_brightness brightness max_brightness subsystem uevent
    bl_power device power type


    >echo -127 50 | sudo tee /sys/class/backlight/acpi_video0/brightness
    -127 50
    tee: /sys/class/backlight/acpi_video0/brightness: Invalid argument

  6. #6
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    Re: Brightness Adjustment PRoblem

    Hmm... invalid value.

    Please post:
    Code:
    grep . /sys/class/backlight/acpi_video0/*
    It should have output similar to this:
    Code:
    /sys/class/backlight/acpi_video0/actual_brightness:10
    /sys/class/backlight/acpi_video0/bl_power:0
    /sys/class/backlight/acpi_video0/brightness:10
    /sys/class/backlight/acpi_video0/max_brightness:10
    That should tell us the values it has set now.
    Multi-Boot= Various flavours of Windows, Linux and Unix... Ubuntu user # 33563, Linux user # 533637
    Sticky: [all variants] Graphics Resolution- Upgrade /Blank Screen after reboot
    Boot Info Script courtesy of community member meierfra

  7. #7
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    Re: Brightness Adjustment PRoblem

    > grep . /sys/class/backlight/acpi_video0/*

    /sys/class/backlight/acpi_video0/actual_brightness:8
    /sys/class/backlight/acpi_video0/bl_power:0
    /sys/class/backlight/acpi_video0/brightness:8
    /sys/class/backlight/acpi_video0/max_brightness:16
    /sys/class/backlight/acpi_video0/type:firmware

  8. #8
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    Re: Brightness Adjustment PRoblem

    "brightness" is the current-setting "file".

    Okay, seems values to be from 16 to 0, where 16 would be max brightness and 0 would be turned off.

    Please try:
    Code:
    echo 16 | sudo tee /sys/class/backlight/acpi_video0/brightness
    Or whatever number you think may be what you want between 0 and 16...
    Lets see if that works.
    Multi-Boot= Various flavours of Windows, Linux and Unix... Ubuntu user # 33563, Linux user # 533637
    Sticky: [all variants] Graphics Resolution- Upgrade /Blank Screen after reboot
    Boot Info Script courtesy of community member meierfra

  9. #9
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    Re: Brightness Adjustment PRoblem

    echo 0 | sudo tee /sys/class/backlight/acpi_video0/brightness
    0


    But nothing changes. Brightness is the same.

  10. #10
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    Re: Brightness Adjustment PRoblem

    Quote Originally Posted by carkaci View Post
    echo 0 | sudo tee /sys/class/backlight/acpi_video0/brightness
    0


    But nothing changes. Brightness is the same.
    Let's try this in a different format than what Ubuntu's Wiki says to follow... by tweaking it in from a different perspective.

    Please try it this way:
    Code:
    sudo echo 0 | tee /sys/class/backlight/acpi_video0/brightness
    Last edited by MAFoElffen; February 4th, 2013 at 12:58 AM.
    Multi-Boot= Various flavours of Windows, Linux and Unix... Ubuntu user # 33563, Linux user # 533637
    Sticky: [all variants] Graphics Resolution- Upgrade /Blank Screen after reboot
    Boot Info Script courtesy of community member meierfra

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