On Mon, 18 Dec 2006, Pete Zaitcev wrote:

> On Mon, 18 Dec 2006 23:02:36 +0100, Paolo Abeni <[EMAIL PROTECTED]> wrote:
> 
> > The code for interfacing with the new binary API has not been merged yet
> > into libpcap. If this really matters, I suppose it can be changed...
> 
> Thanks. I wrote everything (ok, just 3 lines of patch twice, plus docs),
> but now I really do not want to do it because it confuses the attribute
> of a transfer with an attribute of an endpoint. Maybe Alan's phylosophy
> is different. Does an endpoint exist if you do not transfer to it,
> like a sound which nobody can hear? On the other hand, the endpoint
> type must be matching the transfer type as well.

The general trend in USB is to treat the direction as part of the
endpoint's identification.  For instance, we say that a device can have up
to 32 endpoints (16 IN and 16 OUT).  And ep1-out (0x01) is definitely
_not_ the same endpoint as ep1-in (0x81) -- it's even legal to have them
belong to two different interfaces.

(On the other hand we always refer to endpoint 0 the same way, regardless 
of the direction of a transfer.  But of course ep0 is special.)

Anyway, everybody who's used to USB will expect the direction to go with
the number rather than the type because that's the way it is in the
descriptor.

Alan Stern

P.S.: Yes, endpoints do exist even when nobody transfers data to them.  
Proof: "lsusb -v" will list them.


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