David Cross wrote: > > > > > 1) cannot have two gadget peripheral controllers as modules in a given > > > > > kernel > > > > > > > True. > > > > > > Is this behavior by design or accident? > > > Design. The USB specs only allow one upstream > > port, meaning one USB peripheral controller in > > any USB-certified device. > > > So why would we bother trying to support two, if > > that's contrary to the standards we follow?? > > The USB spec allows one upstream facing port, but that does not necessarily > mean one USB peripheral controller per device. There are many mobile devices > on the marketing that have two physical controllers connected to the same > upstream port through a USB switch. These devices are USB certified, so by > definition of the certification this implementation is not contrary to the > standards we follow. > Also, as another example, you could have two physical USB peripheral controllers on an SoC, with one of them meant for inter-chip connections with a host on the same PCB, and the other meant to be exposed to the outside world as the upstream facing port. - Anand -- 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
