On Wed, 3 Sep 2014, Peter Chen wrote: > > Okay. Let's start by adding the reset field to struct > > usb_gadget_driver. The initial implementation in the four gadget > > drivers can be very simple: It calls the disconnect handler. (At some > > later time we can add a ->reset callback to struct > > usb_composite_driver; then the reset handler in composite.c can invoke > > that callback for all function drivers that define it.) > > > > Next, add routines to udc-core to handle Vbus changes, function > > activation changes, and resets. The Vbus routine will invoke the > > gadget driver's ->disconnect callback when Vbus goes off and then call > > usb_gadget_disconnect. The activation routine will call > > usb_gadget_disconnect if any functions are deactivated, and > > usb_gadget_connect if all the functions are activated (basically, do > > whatever composite.c would do). And the reset routine will invoke the > > gadget driver's ->reset callback. I suppose we'll also have to add > > fields to struct usb_gadget, to store the current Vbus and activation > > statuses. > > If the usb_gadget_disconnect will be not called at gadget driver's > ->disconnect, it has no much meaning we still have gadget driver's > ->reset, since the content of its ->disconnect and ->reset are the > same if we don't consider to add function's reset handler. No, they aren't always the same. For example, g_mass_storage ought to flush its dirty buffers when a disconnect occurs, but it doesn't have to flush them when a reset occurs. > > Then modify all the UDC drivers; make them invoke the new udc-core > > routines whenever there's a change in Vbus status or a reset, instead > > of invoking the gadget driver's callbacks directly. At the same time > > we can remove the code that turns off the pullup when Vbus > > goes down, because now the udc-core routine will take care of it. > > Why we need to record the reset at udc-core? We don't really need to. But it seems like a good idea to have events that affect the entire device (including connect, disconnect, reset, and probably also bus suspend and bus resume) all pass through udc-core. 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
