[pxc] AGC on generic Bt and/or PXC200*

[Alessandro Rubini]

> How do I disable the Auto Gain Control (AGC) on my card?
> (At the moment a generic Bt 878)

Same problem here with a generic 878.
 
> I've figured out that it is bit 6 on the SCLOOP register pair, and am 
> assuming that I only have to switch it off.

Interesting. Can you please send me more detailed infromation (possibly
offlist)? I'm very busy and I know I wouldn't set up to look for it.
 
> Is there any way which I can control this from my program via ioctl calls?

Currently not, but it's easily done. If I have the information already
cleaned up I can send a patch during next week.

> My application is such that I switch between different cameras
> faster than the AGC can adapt, and I control the video
> level/saturation/brightness/contrast manually and explicitly.

One idea I had (in reply to Daniel Senie's needs) was to have a set of
configurations per-grabber and per-camera (when using the mux), so
things are properly initialized at boot and switching the mux will
also fix that stuff.

I wanted to use a smart "humanreadable-to-bitdescription" engine like
the one I've dont for evacquo (ftp://ar.linux.it/pub/evacquo) but
never got the time and sufficient motivation to do it.

Would that still be interesting? Someone willing to sponsor it?

/alessandro