On Sun, 8 Jul 2012, Kevin Cernekee wrote: > On Sun, Jul 8, 2012 at 5:33 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > On Sun, 8 Jul 2012, Kevin Cernekee wrote: > > > >> usb_gadget_remove_driver() runs through a four-step sequence to shut down > >> the gadget driver. For the case of a composite gadget + at91 UDC, this > >> would look like: > >> > >> udc->driver->disconnect(udc->gadget); // composite_disconnect() > >> usb_gadget_disconnect(udc->gadget); // at91_pullup(gadget, 0) > >> udc->driver->unbind(udc->gadget); // composite_unbind() > >> usb_gadget_udc_stop(udc->gadget, udc->driver); // at91_stop() > >> > >> composite_disconnect() says: > >> > >> if (cdev->config) > >> reset_config(cdev); > >> > >> reset_config() sets cdev->config to NULL. composite_unbind() later tests > >> for this: > >> > >> WARN_ON(cdev->config); > >> > >> But SETUP packets may be sent to the composite driver up until the point > >> when usb_gadget_disconnect() returns. > > > > That doesn't sound right. A host can't send SETUP packets to a > > disconnected port. The packets should stop arriving when > > udc->driver->disconnect returns -- assuming the UDC driver implements > > a disconnect method. > > udc->driver->disconnect points to composite_disconnect(). What is > composite_disconnect() doing to tell the UDC driver to disconnect the > port from the host? Oops -- you're right and I was wrong. It's the usb_gadget_disconnect() call which turns off the pullup. Sorry about the confusion. > What I see is that usb_gadget_disconnect() does tell the UDC driver to > stop activity on the port, but that only happens after > composite_disconnect() was called. Can you confirm that the order of > the calls in usb_gadget_remove_driver() is correct? They might need to be changed. It does seems like a bad idea to tell the gadget driver that a disconnect occurred before the host knows about it. If you change the order of those two calls, does that make your posted patch unnecessary? 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
