On Tue, 20 Apr 2010, Greg KH wrote: > On Tue, Apr 20, 2010 at 06:09:05PM +0100, Jonathan Wilson wrote: > > I've looked around the net and not found anything, although that might > > be because I'm using the wrong search words, for something similar to > > the following. > > > > What I'm looking for is, kind of, in two parts. > > > > One is some form of USB-OTG gadget driver virtual hub, so that a > > peripheral device connected to a PC would fake it's self into appearing > > as a standard physical hub. Obviously such a hub would either have to > > fake its device id's/types/sub/etc. to pretend to be an existing hub, or > > would require a new id, etc; properly registered. > > The main problem is that the majority of what a hub does needs to be in > hardware, due to the speed issues that are required here. not to > mention the complexities of properly handling the USB protocol (USB 2.0 > hubs with USB 1.1 devices plugged into them are nasty things, it took a > long time to get that hardware right...) > > So just by virtue of the electronics involved, this might be a very > impossible wish, sorry. That's right. Even at the most superficial level there's a fundamental problem: The USB-OTG device controller hardware will respond only to packets sent to its own address. But if it had virtual devices "plugged in" (in the form of gadget drivers), then it would also have to respond to packets sent to these devices' addresses. Clearly that cannot be made to work. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
