USB device implementation

Warner Losh imp at bsdimp.com
Tue Jan 17 11:30:33 PST 2006


> On Tuesday 17 January 2006 06:03, Alexander Leidinger wrote:
> > "Michael S. Eubanks" <mse_software at charter.net> wrote:
> > > Okay.  I will look into it some more.  I need to get better idea
> > > of how the USB driver code works.  It looks like there are only
> > > minor differences between my current driver code and the NetBSD
> > > code.  With respect to any questions and changes I make, should I
> > > contact mux@ directly using the email address listed on the
> > > contributors page?
> >
> > Every FreeBSD committer should expect to get a mail with some
> > questions, so mailing to mux at FreeBSD.org is not forbidden. :-)
> >
> > But he's not "the USB guy in the block". He just tries to port the
> > uhidev code (maybe because he needs it). So don't expect an answer
> > to every question.
> >
> > Unfortunately we don't have an active USB guru around, except
> > Hans-Petter Selasky (not a FreeBSD committer), but he develops a
> > rewritten-from-scratch USB stack. So don't expect him to be able to
> > answer questions reagarding the USB stack in -current.
> From my personal experience and just looking at the commiter that has 
> been touching the usb files I'd add Ian Dowse <iedowse at freebsd.org> 
> to that short guru list.  He has been pretty busy recently, but if 
> you're willing to do your homework I'm sure he'd be happy to answer 
> any questions.

I've also been doing a bunch inside the usb stack, although not having
enough time either.

> > So far HPS wasn't able to convince a committer to import his work.
> > Partly because we think that a USB stack which is shared between
> > the BSD's may be better, partly because the existing stack seems to
> > work good enough for those committers which may be willing to
> > import the new one or be able to mentor HPS.
> As Warner said it takes time to work through such a large change.  
> Hans-Petter Selasky stack is trying to be free of the GIANT lock and 
> that's a bit tricky with USB, but ultimately the direction we are 
> heading for 7.0.

Yes.  There's also some concerns over the safety of the novel locking
scheme that has been proposed for usb that take a lot of time and
energy to work out.  Eg, are they any better than the stock tools,
does it work?  Does it fill a void in our stock tools? etc

Warner


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