> I'm considering writing a driver for a USB webcam.

Good timing - I was just trying to get my USB CPiA camera to
work last night with the ugen driver...
(I can get images now, but not reliably.)
Is there any particular reason to write a specific driver,
as opposed to using ugen and maybe a userland libvideo
or something to provide a common API?

> The question is what API it should present to useland software.
> Is the bktr driver API the way to go?

No.  For one thing, many of the defined constants and structures
have names that go back to when the driver was originally written for
the Matrox Meteor (ie, METEORSETGEO, struct meteor_geomet, etc.)

You might want to look at the video4linux stuff, although whether
you should consider that how to do it, or how not to do it, I
don't know... :-)

   -Jeff