On Thu, Apr 07, 2011 at 01:22:10PM +0300, Tanya Brokhman wrote: > > > But these gadgets won't work at USB 3.0 speeds when plugged into a > > USB > > > 3.0 host, correct? > > > > I don't know about that. Obviously the gadget would need to have > > descriptors appropriate for SuperSpeed operation, but with > > autoconfiguration this doesn't have to be too hard. > > Auto configuration isn't complicated. That's what we did in our > implementation of the "SS support to the Gadget Framework" patch series. > > > However you're asking about the gadgets' operation. Obviously the > > device controller would have to support SuperSpeed. Apart from that, > > however, I don't think much change in the gadget drivers would be > > needed. > > The only changes required for existing gadget drivers to operate in SS are: > 1. adding the SS descriptors - can be done automatically by > create_ss_descriptors() implemented in our patch series. > 2. choosing the SS descriptors when operating in SS mode. > So the changes are indeed not that serious. Ok, that's fine. I just wanted to avoid any headache on the host side when these USB 3.0 devices start showing up. Not trying to impede progress or anything. :) > > > For > > > example, how is a USB 3.0 webcam supposed to work, now that there are > > > additional isochronous transfer opportunities per frame (over USB 2.0 > > > isoc devices). We don't know yet. > > > > As a reasonable first attempt, it could work exactly the same as it > > does at high speed. Nothing says it has to make use of all the > > available isochronous transfer opportunities. True, that would work. But the USB 3.0 devices also need to be able to handle things like link power management and function power management. I know that USB 3.0 devices won't pass the USB-IF compliance tests if they don't handle link PM. Was that also in Tanya's SuperSpeed gadget patchset? If you don't care about link power management for a first pass, that's fine with me. However, I think the devices should at least be able to refuse to go into a lower power link state when they are sent the LPM commands by the USB 3.0 hub or host. Probably that will be taken care of in the device controller, but maybe there's some gadget-side software that needs to enable that? Sarah Sharp -- 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
