Re: LDP and comedi

On 10/25/07, Herman Bruyninckx <Herman.Bruyninckx_at_mech.kuleuven.be> wrote:
> BTW, what are, in the opinion of the Comedi users/developers, the real
> 'showstoppers' to move to "1.0"...?

It's been several months since I looked at it, but I recall that the
encoder / counter API was confusing.  Or perhaps it was fine, and it
was the documentation that was confusing...

We had been using a Quanser Q8 card to run a prototype robot at my
employer, and I thought I'd clean up and port the driver we were using
to comedi... but though it is ultimately a digital and analog I/O
device, the Q8 card has several features oriented towards motion
control that didn't seem to fit into the comedi abstraction very well.
 Since we had picked that card specifically for those features, I
ended up abandoning the comedi port.  I'd be happy to pick it up again
if it would shed some light on the dusty corners of the API.

In general, I would say that the pieces that are widely implemented
among comedi drivers (analog and digital I/O, instructions and
commands) are fine.  The parts that are listed as "experimental" in
the comedi documentation (encoders and counters, filtering options,
waveform generation, advanced trigger settings) need to be cleaned up
and documented if they're going to be frozen into a mainline kernel
API.

Though I'm not personally familiar with it, we may be able to take
some inspiration from Video for Linux 2... video capture cards are
also a class of devices that all generally do the same thing, but have
tons of device-specific configuration options that need to be taken
into account.  There's been a long series of articles explaining the
v4l2 kernel API at lwn.net:

http://lwn.net/Articles/203924/

-Tabish

Received on 2007-10-25Z09:54:18