Re: use of an intermediate device to handle USB interfaces

[David Brownlee <abs%NetBSD.org@localhost>]

On Thu, 7 Feb 2008, Matthias Drochner wrote:

> mouse%Rodents.Montreal.QC.CA@localhost said:
> > I recently did an install on a fairly vanilla server system.  I
> > counted nine PCI busses in the autoconf output - and at least one
> > bridge for each one.  The machine had only one physical PCI bus
> > (connectors &c) as far as I could tell.
>
> My laptop has six of them and not a single PCI slot...
> This is PCIexpress where everything is point-to-point.
> (This could be made use of for power management, but
> the gain of that would arguably be a small increment
> compared to eg savings in the CPU.)
>
> > I'm not clear on the
> > difference between a device and an interface
>
> A device is basically what plugs into a USB slot,
> so eg link and power management is done at this level.
> A device logically consists of (one or more) interfaces.
> Interfaces often belong to some pre-defined interface
> class which can be handled by some class driver.
> Thus drivers for common stuff (storage, keyboards, audio...)
> attach to some interface.

        So (assuming I've understood correctly), ucompound would
        map to a USB device and all NetBSD's existing usb devices
        would really be USB interfaces?

        As a (possibly somewhat insane idea), how would it work to
        merge ugen and ucompound - it could potentially allow people
        to poke at any device via the ugen interface at the cost
        of cluttering up the list of 'real' ugen devices...


--
                David/absolute       -- www.NetBSD.org: No hype required --