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Thread: Acer Aspire 5749 screen brightness

  1. #31
    Join Date
    Jan 2012
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    9

    Re: Acer Aspire 5749 screen brightness

    Quote Originally Posted by Toz View Post
    Hmmm. What is the value in that file prior to initiating suspend?
    It doesn't exist but after closing/opening the lid, it has 0 inside.

  2. #32
    Join Date
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    Toronto, Canada
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    Xubuntu 16.04 Xenial Xerus

    Re: Acer Aspire 5749 screen brightness

    In post #23, the your response showed that it did exist. Can you try this (before suspend) and post back the results:
    Code:
    ls /sys/class/backlight
    Code:
    for b in `ls /sys/class/backlight`; do echo "$b"; cat /sys/class/backlight/$b/brightness; cat /sys/class/backlight/$b/max_brightness; done

  3. #33
    Join Date
    Jun 2009
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    10

    Re: Acer Aspire 5749 screen brightness

    Hello Toz,

    After you open the lid (using both acpi_osi=Linux & acpi_backlight-vendor), do the function keys allow you to increase brightness (try both up and down brightness keys.
    Yes I can increase and decrease the brightness with the function keys with both options as well as with only the option acpi_backlight-vendor, acpi_osi=Linux doesn't seem to have an impact.

    Also, try going to TTY1 (press Ctrl+Alt+F1 and back to TTY7 (press Ctrl+Alt+F7). Does the brightness return?
    Going to TTY1 and returning back to TTY7 brings back the happily shining screen no matter if acpi_osi=Linux & acpi_backlight-vendor are active or not


    And last but not least here are my results for echoing the screen brightness directly in the terminal:

    First without acpi_osi=Linux & acpi_backlight-vendor

    Code:
    ~$ cat /sys/class/backlight/intel_backlight/brightness
    976
    ~$ cat /sys/class/backlight/acpi_video0/brightness
    0
    ~$ cat /sys/class/backlight/intel_backlight/max_brightness
    976
    ~$ cat /sys/class/backlight/acpi_video0/max_brightness
    9
    Code:
    ~$ echo 15 | sudo tee /sys/class/backlight/intel_backlight/brightness
    15
    -> the screen brightness changes

    Code:
    ~$ echo 15 | sudo tee /sys/class/backlight/acpi_video0/brightness
    15
    tee: /sys/class/backlight/acpi_video0/brightness: the argument is not valid
    -> the screen brightness doesn't change


    Next with active acpi_osi=Linux & acpi_backlight-vendor

    Code:
    ~$ cat /sys/class/backlight/acpi_video0/brightness
    cat: /sys/class/backlight/acpi_video0/brightness: file or folder not found
    ~$ cat /sys/class/backlight/acpi_video0/max_brightness
    cat: /sys/class/backlight/acpi_video0/max_brightness: file or folder not found
    Code:
    ~$ echo 15 | sudo tee /sys/class/backlight/intel_backlight/brightness
    -> the screen brightness changes

    Code:
    ~$ echo 15 | sudo tee /sys/class/backlight/acpi_video0/brightness
    tee: /sys/class/backlight/acpi_video0/brightness: file or folder not found
    -> the screen brightness doesn't change

    I hope this helps a little bit ...
    jb

  4. #34
    Join Date
    Jun 2009
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    Re: Acer Aspire 5749 screen brightness

    P.S.

    Code:
     for b in `ls /sys/class/backlight`; do echo "$b"; cat /sys/class/backlight/$b/brightness; cat /sys/class/backlight/$b/max_brightness; done
    acpi_video0
    0
    9
    intel_backlight
    976
    976

  5. #35
    Join Date
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    Location
    Toronto, Canada
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    Xubuntu 16.04 Xenial Xerus

    Re: Acer Aspire 5749 screen brightness

    Quote Originally Posted by jayarbie View Post
    P.S.

    Code:
     for b in `ls /sys/class/backlight`; do echo "$b"; cat /sys/class/backlight/$b/brightness; cat /sys/class/backlight/$b/max_brightness; done
    acpi_video0
    0
    9
    intel_backlight
    976
    976
    Ok, since acpi_osi=Linux doesn't make a difference, then drop it.

    From what I understand, acpi_backlight=vendor fixes the issue with the brightness keys not working, but introduces a secondary problem where after you close and re-open the lid, the brightness is all the way down.

    If this is correct, then you have 2 options:
    1. On opening of lid, use the brightness keys to re-adjust the brightness

    2. To automate this, create the following file:
    Code:
    gksudo gedit /etc/pm/sleed.d/20reset_brghtness
    ...with the following content:
    Code:
    #!/bin/bash
    
    case "${1}" in
        hibernate|suspend)
           #do nothing
           ;;
        resume|thaw)
           echo 976 > /sys/class/backlight/intel_backlight/brightness
           ;;
    esac
    ...save the file and make it executable:
    Code:
    sudo chmod +x /etc/pm/sleed.d/20reset_brghtness
    ...and give it a try.

  6. #36
    Join Date
    Dec 2010
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    17

    Re: Acer Aspire 5749 screen brightness

    I've got the same problem with the same controller. My brightness is at 100% all the time no matter what. Laptop is Acer 7750-6423 running 11.10 freshly installed. I've tried all the steps in this post and a couple of other things to no avail. Note that using the brightness keys (Fn <- and Fn -> for me) does show a graphic indicating that the brightness is changed. Doing this also changes the brightness value in the brightness file mentioned in a couple of places in this thread...but that obviously has no effect.

    Quote Originally Posted by Toz View Post
    As a first suggestion, try booting with the kernel parameters: acpi_osi=Linux acpi_backlight=vendor

    If no luck, post back the results of the following commands:
    Code:
    sudo lspci -vnn | grep -A10 VGA
    00:02.0 VGA compatible controller [0300]: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0116] (rev 09) (prog-if 00 [VGA controller])
    Subsystem: Acer Incorporated [ALI] Device [1025:050e]
    Flags: bus master, fast devsel, latency 0, IRQ 41
    Memory at c0000000 (64-bit, non-prefetchable) [size=4M]
    Memory at b0000000 (64-bit, prefetchable) [size=256M]
    I/O ports at 3000 [size=64]
    Expansion ROM at <unassigned> [disabled]
    Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
    Capabilities: [d0] Power Management version 2
    Capabilities: [a4] PCI Advanced Features
    Kernel driver in use: i915

    Quote Originally Posted by Toz View Post
    Code:
    dmesg
    ls /sys/class/backlight
    :~$ ls /sys/class/backlight/
    acpi_video0 intel_backlight

    dmesg is in the attached tarball along with Xorg.0.log

    Quote Originally Posted by Toz View Post
    ...and the contents of /var/log/Xorg.0.log
    thanks for any guidance. this brightness is killing my eyes. ouch. I've got the weekend to resolve the issue or it goes back to the Mart of Wal from whence it came.
    Attached Files Attached Files

  7. #37
    Join Date
    Jun 2009
    Beans
    10

    Re: Acer Aspire 5749 screen brightness

    Hello,

    yesterday I received a kernel update to 3.0.0-15-generic x86_64 and at the moment I think using the boot option acpi_backlight-vendor does not cause the problem anymore (screen stays black when re-opening the lid). I will watch this for a while and test it in various constellations.

    Thank you so far!
    jb

  8. #38
    Join Date
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    Location
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    Xubuntu 16.04 Xenial Xerus

    Re: Acer Aspire 5749 screen brightness

    @MFaughn, try updating your kernel to the newest version (3.0.0-15). Also, try with just the acpi_backlight=vendor parameter. After you boot with this parameter, post back the results of:
    Code:
    cat /proc/cmdline
    ...and whether it works or not.

  9. #39
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    Re: Acer Aspire 5749 screen brightness

    Quote Originally Posted by jayarbie View Post
    Hello,

    yesterday I received a kernel update to 3.0.0-15-generic x86_64 and at the moment I think using the boot option acpi_backlight-vendor does not cause the problem anymore (screen stays black when re-opening the lid). I will watch this for a while and test it in various constellations.

    Thank you so far!
    jb
    Yes. Kernel 3.0.0-15 includes a fix for intel i915 backlight problems as documented here: https://bugs.launchpad.net/ubuntu/+s...ux/+bug/872652. Hopefully this fixes your issue.

  10. #40
    Join Date
    Oct 2011
    Beans
    11

    Re: Acer Aspire 5749 screen brightness

    I confirm, with the new kernel and update to the grub configuration the brightness buttons work.
    To use this fix

    1. Update your system

      Code:
      sudo apt-get update 
      sudo apt-get upgrade
    2. Edit the kernel load parameters:

      Code:
      sudo gedit /etc/default/grub
      There change the line starting as:
      Code:
      GRUB_CMDLINE_LINUX_DEFAULT="quiet splash ... so on ... "
      adding a space before the closing quote" and a parametter setting
      acpi_backlight=vendor
      I had this line:
      Code:
      GRUB_CMDLINE_LINUX_DEFAULT="quiet splash i915.i915_enable_rc6=1 acpi_backlight=vendor"
      Save the file, exit the editor.
    3. Update GRUB
      Code:
      sudo update-grub
    4. Reset your PC. Should work!



    I thank everyone for help very much!

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