USB drivers

M. Warner Losh imp at
Sat Aug 7 15:01:34 PDT 2004

In message: <000001c47cb8$8ef1bb50$142a15ac at spud>
            "Darren Pilgrim" <dmp at> writes:
: > From: M. Warner Losh
: > 
: > In message: <41124C8B.2060902 at>
: >             Chris <chris at> writes:
: > : 
: > : What I am trying to determine is why my multifunction
: printer/scanner 
: > : receives only one of the two  drivers. Is it because the printer
: does 
: > : not respond properly? Is it because the printer is not defined? I
: > : have many questions here.
: > 
: > Yes.  Usb is a little complicated in this area, and there are a number
: > of details that are hard to get right.  It wouldn't surprise me if the
: > current set of drivers are less than completely optimal.
: On a bit of a side-track, I'm wondering if it could be due to how the
: multifunction device presents itself?  A bit back in this thread someone
: mentioned that a pointer must be present for a driver to attach to a
: device.  If there is only one pointer for a device, only one driver may
: attach.  Since a single USB bus can have a LOT of devices and each
: device's capabilities are determined through the presence of usage
: pages, I see two ways for a multifunction device to present itself:
: - A single device ID with more than one usage page.  All the
: functionality is there and is compatible with FreeBSD drivers, but since
: there is only one device probed on the bus, only one driver may attach.
: Perhaps a "simple" mux driver would be useful?
: - A multiple single-usage device IDs.  Same functionality as before, but
: now FreeBSD can probe unique printer and scanner devices and thus let
: both ulpt and uscanner attach simutaneously.
: Am I way off base?

No.  You are exactly on base.  That's why I pointed at you at the usb
information program.  Run it with the device plugged in, and we'll be
able to know the details.


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