Interfacing nvidia graphics cards and acpi brightness

Peter Newman Peter.Newman at
Thu Mar 20 00:10:33 UTC 2008

(Answering my own question)
Clues are found here:
Nvidia say that ACPI and hotkeys hasn't been implemented for all cards
yet but might be in the future for more recent ones.
A couple of XConfig options to play around with were: 
 Option "ConnectToAcpid" "boolean"
 Option "EnableACPIHotkeys" "boolean"
No luck for the Quadro FX 570M as far as I could tell
I still think that it should be possible to implement ACPI compatibility
through an some sort of abstraction layer by linking ACPI events to
nvidia-settings so that there would be no need to wait for nvidia.
Alternatively one could play with the open source Nouveau drivers


From: ubuntu-devel-discuss-bounces at
[mailto:ubuntu-devel-discuss-bounces at] On Behalf Of
Peter Newman
Sent: Tuesday, 18 March 2008 11:52 PM
To: ubuntu-devel-discuss at
Subject: Interfacing nvidia graphics cards and acpi brightness


I started out tonight with the aim of adding a bug because my compaq
8510w brightness function keys have never worked under Ubuntu Gutsy and
now not under Hardy Heron alpha 6 either.

However what I have found is that there is no bug to report :)

The gnome-power-manager works okay but doesn't change screen brightness.
I.e. hitting the function key does change the current value here:

 $ cat /proc/acpi/video/C14B/C15F/brightness

 levels:  100 51 30 37 44 51 58 65 72 79 86 93 100
 current: 65

Also adjusting the nvidia-settings brightness values actually changes
the screen brightness (and the nvidia card registers) but nothing for
the acpi video brightness value.

I've also found that I can adjust the screen brightness by using the
nvidia commandline interface:

 $ nvidia-settings --assign RedBrightness=x --assign GreenBrightness=x
--assign BlueBrightness=x

where x is a value between -1 and 1.

So where now - there is no bug?

I've looked at smartdimmer and nvclock.  These packages don't work for
all nvidia cards and seem to be risky to use.  Especially when there is
a nvidia-settings package available which can already do this.

So I think that acpi should be linked to nvidia-settings somehow (I
suppose this should be the responsibility of nvidia).  Would a
acpi-nvidia package work (where acpi and nvidia-settings are
prerequistes and also an active nvidia kernel/xserver) that matches acpi
video and xserver screens and sychronises registry settings?


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