I had this issue, the Fn keys need to be mapped to setpci commands
(do-able in xorg.conf somewhere)
However;
"setpci -s 00:02.0 F4.B=xx" Where xx is the desired brightness in HEX
will allow you to adjust the hardware brightness factor.
Hope it helps
On Tue, 2011-04-05 at 06:20 -0400, matthammal@??? wrote:
> 
> >Dear Friends
> 
> >I installed Ubuntu Netbook 10.10 in a partition alongside the provided 
> 
> >Windoze 7 in my new-last-week Samsung N145.
> 
> >It's a lot easier to get into the system on my PC running Ubuntu 10.10.
> 
> >As a relative newcomer to Linux I've been working at learning to use 
> 
> >Terminal and thought that was coming along nicely until I came upon my 
> 
> >current problem: I can't get the display to un-dim.
> 
> >In Windoze mode the 'Fn' and 'up' or 'down' buttons control brightness 
> 
> >OK, but using these in Linux brings up an on-screen flickering slider 
> 
> >which doesn't work and necessitates an escape routine with the on-off 
> 
> >switch.
> 
> >I got into 'Power Management Preferences' and the sliders there don't 
> 
> >work - the screen stays in power-saving rather-dim mode.
> 
> >Clicked on 'Help' and there is lots of apparently useful stuff there and 
> 
> >a 'pinned post-it' :  "Some sliders or option boxes may be disabled if 
> 
> >the GConf policy keys are not writable. This allows administrators to 
> 
> >lock down the actions that a user can select."
> 
> >So I tried Terminal but can't find a way into   GConf    or    
> 
> >/app/gnome-power-manager/backlight/idle_brightness
> 
> >When I first installed Linux on the machine, I am sure the brightness 
> 
> >was fine but I don't know what I did that changed it.
> 
> >
> 
> >Any ideas on how I could control the display backlight please?
> 
> >
> 
> >Tony Wood
> 
> 
> 
> Try the following (from French Ubuntu forum):
>         sudo add-apt-repository ppa:voria/ppa
>         sudo apt-get update && sudo apt-get upgrade
>         sudo apt-get install samsung-tools samsung-backlight
>         sudo reboot
> It appears on some systems the function keys begin working but the
> brightness does not change. In this case, try appending
> “acpi_backlight=vendor” to the GRUB_CMDLINE_LINUX line in Suspend /
> Resume below.
>         GRUB_CMDLINE_LINUX=”acpi_sleep=nonvs acpi_backlight=vendor”
> 
> 
> --
> Please post to: Hampshire@???
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