On Friday 25 May 2007, Alan Stern wrote: > On Thu, 24 May 2007, David Brownell wrote: > > On Thursday 24 May 2007, Alan Stern wrote: > > > > After all, an OTG device is required to have no > > > more than one USB connection, so the port number would always be equal > > > to udev->portnum and to 1. > > > > Not true. It's perfectly legit for a host to have multiple host > > ports, with only one of them being OTG-capable. > > Really? What about section 3.2 in the OTG spec, where it says that an > On-The-Go device must include: > > one, and only one connection: a Micro-AB receptacle.
You omitted the "(except as noted in Section 3.8)", which says that a second connector is allowed iff it's a Mini-A connector. That's a trivial counter-example... But in any case, section 3 is only talking about connectors, not links that may be used internally on a mainboard and which would not be externally visible. The example I gave was for an on-mainboard device. (I've seen similar products using SDIO to access modem chips. Again, nothing visible to the end users; just boards leveraging volume pricing for parts using a wire-efficient I/O bus.) > Has this been superseded? Or do people simply ignore it? Rev 1.2 changed from 1.0a here; ISTR that 1.0a allowed more than one such connector, and allowed standard-A too. But also keep in mind that the constraint is on externally visible connectors, to reduce end-user confusion. And that as the section 3 intro says, the text there doesn't address technical details ... just the highlights. - Dave > > Not uncommon either; > > it's a simple implementation strategy (combining existing silicon IP > > with an OTG engine), and board designers find serial busses like USB > > are handy as a way to integrate various devices ... simple to route > > on the boards, only two pins, and so forth. It's not just a way to > > connect external devices. > > Alan Stern > ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
