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#1 2012-01-24 05:13:23

twelveeighty
Member
From: Alberta, Canada
Registered: 2011-09-04
Posts: 1,096

Screen brightness adjustment broken

Since the latest updates to the kernel/udev/kmod, I can no longer control my screen brightness via KDE. This used to work perfectly. Neither the Fn-F6/F7 key combination, nor the "Screen Brightness" slider on the KDE power management tool changes the brightness.

Is this a known issue? If so, is there a workaround...?

I use a Toshiba A500 laptop. Like I mentioned, this worked last week, before I ran pacman -Syu :-(

The real problem is that it seems stuck at the highest brightness - this is draining my battery within 20 minutes.

Is there another way to adjust the screen brightness?

Last edited by twelveeighty (2012-01-24 05:14:38)

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#2 2012-01-24 06:18:23

dptkby
Member
Registered: 2009-07-02
Posts: 64

Re: Screen brightness adjustment broken

I don't know what caused the problem, but people occasionally have luck adding something like acpi_osi=Linux and/or acpi_backlight=vendor to their kernel parameters. These might be worth experimenting with... have a look at http://www.kernel.org/doc/Documentation … meters.txt.

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#3 2012-01-24 20:40:02

dinsdale
Member
From: Riviere-du-loup
Registered: 2010-06-04
Posts: 15

Re: Screen brightness adjustment broken

what is your gfx card,  don't know this model.

For NVIDIA I had to add the following to /etc/X11/xorg.conf.d/15-nvidia.conf

       
Option "RegistryDwords" "EnableBrightnessControl=1"               

So now it reads:
                                                                                                           
Section "Device"                                                                                                                                                                       
        Identifier     "Device0"                                                                                                                                                       
        Driver         "nvidia"                                                                                                                                                       
        VendorName     "NVIDIA Corporation"                                                                                                                                           
        Option "RegistryDwords" "EnableBrightnessControl=1"                                                                                                                           
        # Option "RandRRotation" "true"                                                                                                                                               
        Option "NoLogo"        "true"                                                                                                                                                 
        Option "Coolbits"      "1"                                                                                                                                                     
        Option "TripleBuffer"  "True"                                                                                                                                                 
        # Option "DamageEvents"  "True"                                                                                                                                               
        # Option  "UseEvents"    "True"                                                                                                                                               
        # Option "BackingStore" "True"                                                                                                                                                 
        Option "DPMS" "True"                                                                                                                                                           
        # Option "RegistryDwords" "PerfLevelSrc=0x3333"                                                                                                                               
EndSection

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#4 2012-01-25 02:12:02

twelveeighty
Member
From: Alberta, Canada
Registered: 2011-09-04
Posts: 1,096

Re: Screen brightness adjustment broken

@dinsdale: I have an nvidia card (GeForce 310M), but I have no such file /etc/X11/xorg.conf.d/15-nvidia.conf; could that be because I am running the nouveau driver?

@dptkby: tried that and no luck...

Would anyone know which component broke this? The kernel, kmod, udev or some other component? It would quite the pain trying to reverse each one and see if that fixes it....

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#5 2012-01-25 02:14:35

dinsdale
Member
From: Riviere-du-loup
Registered: 2010-06-04
Posts: 15

Re: Screen brightness adjustment broken

twelveeighty wrote:

@dinsdale: I have an nvidia card (GeForce 310M), but I have no such file /etc/X11/xorg.conf.d/15-nvidia.conf; could that be because I am running the nouveau driver?

Don't think nouveau has that option. I have the prop driver

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#6 2012-01-25 03:09:33

twelveeighty
Member
From: Alberta, Canada
Registered: 2011-09-04
Posts: 1,096

Re: Screen brightness adjustment broken

I realized that there is a very similar thread in the Laptops forum: https://bbs.archlinux.org/viewtopic.php?id=134132

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