By the way, if I try to do a control out transfer to the g_zero gadget I get 'Pipe error' (using libusb-1.0). Is this expected? On Thu, Nov 9, 2017 at 4:24 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Thu, 9 Nov 2017, Felipe Balbi wrote: > >> >> Hi, >> >> Hinko Kocevar <hinkocevar@xxxxxxxxx> writes: >> >> The way dummy was written, it can only instantiate one gadget. You >> >> either need a real USB peripheral controller, or you need to patch dummy >> >> to instantiate more than one gadget. >> >> >> >> -- >> >> balbi >> > >> > By dummy - are you referring to g_zero of dummy_hcd? >> >> Okay, we need a little more explanation. In order to have a gadget >> driver like g_zero loaded, you need a USB peripheral controller (in your >> case, that's handled by dummy). >> >> Now, when you want that g_zero to be useful, you need to plug it to a >> USB host controller (in your case, that's also handled by dummy). >> >> What I'm saying, though, is that this dummy (dummy_hcd.c) can only >> handle ONE gadget (a fake USB peripheral controller) at a time. It does >> NOT instantiate more than one of those. > > In fact, this isn't correct. See the "num" module parameter in > dummy_hcd.c (added by commit c7a1db457bfc "usb: gadget: dummy_hcd: add > setup / cleanup of multiple HW intances"). > > Alan Stern > >> Because of that, there's no way >> to get g_zero to probe for a second time. >> >> In fact, even if you were to patch dummy_hcd.c to instantiate N gadgets, >> you wouldn't be able to use g_zero.ko, and would be required to rely on >> our configfs interface for dynamically generating and binding different >> gadget drivers to each of your gadget instances, but that's another >> story altogether. > > > -- .. the more I see the less I believe.., AE AoR -- 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
