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Thread: Backlight Problem with Acer Aspire V5

  1. #1
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    Nov 2011
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    Exclamation Backlight Problem with Acer Aspire V5

    Hello, I have an Acer Aspire V5(V5-122P-0408) and I've installed Lubuntu on it(I was gonna dual-boot with Windows, but I accidentally replaced it. Didn't want it anyways, it always used 50% of the CPU in standby). The problem is that I can't seem to dim my laptop's screen. The Fn+Up&Down keys work(I see the OSD), but the screen doesn't dim. I've tried:-
    Code:
    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor vga=792"
    GRUB_CMDLINE_LINUX="acpi_osi=Linux"
    
    However, when I use that, I don't get any OSD at all. The brightness is always stuck at 100% and I can't change it anywhere(BIOS, login screen, etc.) I assume that this is a problem with my UEFI BIOS not reporting the information about the laptop to Ubuntu in a proper way or is this a possible bug in the proprietary AMD Catalyst drivers?

    Thanks for the help.

  2. #2
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    Nov 2011
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    Re: Backlight Problem with Acer Aspire V5

    If anyone is wondering:
    Code:
    uname -r
    3.10.5-031005-generic

  3. #3
    Join Date
    Jun 2005
    Location
    Toronto, Canada
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    Distro
    Xubuntu 14.04 Trusty Tahr

    Re: Backlight Problem with Acer Aspire V5

    Can you post back the following:
    Code:
    cat /proc/cmdline
    Code:
    lspci -nk | grep -A3
    Code:
    for i in /sys/class/backlight/*; do echo $i; cat $i/brightness; cat $i/max_brightness; done
    Have you tried the "acpi_osi=\"!Windows 2012\"" kernel parameter? Like this:
    Code:
    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
    GRUB_CMDLINE_LINUX="acpi_osi=\"!Windows 2012\""

  4. #4
    Join Date
    Nov 2011
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    12

    Re: Backlight Problem with Acer Aspire V5

    Code:
    cat /proc/cmdline
    BOOT_IMAGE=/boot/vmlinuz-3.10.5-031005-generic root=UUID=e0d795b4-adb3-4a25-8ed9-1ad528e482d9 ro "acpi_osi=!Windows 2012" quiet splash vt.handoff=7
    lspci -nk | grep -A3
    returns an invalid syntax error from grep

    Code:
    for i in /sys/class/backlight/*; do echo $i; cat $i/brightness; cat $i/max_brightness; done
    /sys/class/backlight/acpi_video0
    6
    11

    I tried your solution, but it is to no avail. I get an OSD, but the brightness is still not changing.

  5. #5
    Join Date
    Jun 2005
    Location
    Toronto, Canada
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    Distro
    Xubuntu 14.04 Trusty Tahr

    Re: Backlight Problem with Acer Aspire V5

    lspci -nk | grep -A3
    returns an invalid syntax error from grep
    Sorry, that should have been:
    Code:
    lspci -nk | grep -A3 VGA
    Does manually changing the brightness work:
    Code:
    echo 11 | sudo tee /sys/class/backlight/acpi_video0/brightness
    echo 3 | sudo tee /sys/class/backlight/acpi_video0/brightness

  6. #6
    Join Date
    Nov 2011
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    12

    Re: Backlight Problem with Acer Aspire V5

    Code:
    lspci -nk | grep -A3 VGA
    returns null.

    Changing the brightness manually does work. The 11 and 0 dims the screen, but anything below is 100% bright. This is better than before, using 0 and 11 used to give me no light at all so
    Code:
    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
    GRUB_CMDLINE_LINUX="acpi_osi=\"!Windows 2012\""
    works somewhat.

  7. #7
    Join Date
    Nov 2011
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    12

    Re: Backlight Problem with Acer Aspire V5

    Any other suggestions? Do you have any suggestions for filing a bug report with someone? Where do I file it?

  8. #8
    Join Date
    Jun 2005
    Location
    Toronto, Canada
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    Xubuntu 14.04 Trusty Tahr

    Re: Backlight Problem with Acer Aspire V5

    Quote Originally Posted by domefavor95 View Post
    Code:
    lspci -nk | grep -A3 VGA
    returns null.
    *sigh* been a long day. The command should be:
    Code:
    lspci -k | grep -A3 VGA
    Changing the brightness manually does work. The 11 and 0 dims the screen, but anything below is 100% bright. This is better than before, using 0 and 11 used to give me no light at all so
    Code:
    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
    GRUB_CMDLINE_LINUX="acpi_osi=\"!Windows 2012\""
    works somewhat.
    Is there something in the Catalyst Control Centre that allows for brightness changing?

  9. #9
    Join Date
    Jun 2005
    Location
    Toronto, Canada
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    Distro
    Xubuntu 14.04 Trusty Tahr

    Re: Backlight Problem with Acer Aspire V5

    Quote Originally Posted by domefavor95 View Post
    Any other suggestions? Do you have any suggestions for filing a bug report with someone? Where do I file it?
    You can file a bug report against fglrx. What version of ubuntu are you running?

  10. #10
    Join Date
    Nov 2011
    Beans
    12

    Re: Backlight Problem with Acer Aspire V5

    I've looked in the control panel, but there is nothing there except for the video output brightness. I'm running Lubuntu 13.04. If I knew making this netbook work would be so hard, I would have kept Windows. Well, you live and you learn.

    Where do I file the bug report exactly?

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