Re: [ddccontrol-devel] non root i2c communication

[William O. <gun...@on...>]

Hello,

Le 01/12/2009 14:28, Kai-Uwe Behrmann a écrit :
> I have monitor here, which supports reading and writing of internal LUTs 
> over a small monitor framework[1]. It accesses the montor over i2c 
> device nodes. That would be nice to integrate in my graphic card LUT 
> viewer[2].
>
> Unfortunedly i2c requires root access on my system. And my understanding 
> is that i2c is a security issue to open for normal users.
I wasn't aware of that. Where did you get this information from?
> How can my 
> application nevertheless get the curves. As well there is interesst 
> to do more with this monitor communication channel.
>
> Can this be achieved over DDC/CI as well? What would be needed to make it 
> non root read and writeable.
>   
What ddccontrol allows you to do is read and write values that are
stored in the monitor's internal chip, so that you can control
parameters like Brightness, Contrast, color temp, etc. from you
computer, just as you would with the buttons and OSD of your monitor.

ddccontrol can use different low-level protocols to do that : for
example, I can use i2c, or use my Nvidia graphics card driver's
capabilities to communicate with my monitor.

DDC/CI is a protocol that works on top of i2c, so as far as I can tell,
you will still need to run ddccontrol as root to be able to communicate
with your monitor.

A while ago, I tried to make ddccontrol work at a user level, but I
didn't manage. I'm the current maintainer of the project, but I'm quite
busy right now. Maybe we could figure something out together, when we
both have time.

I hope this answers your question.

Regards,

William