usb: gadget: udc-core: stop UDC on device-initiated disconnect

commit 6d258a4c upstream.

When we want to do device-initiated disconnect,
let's make sure we stop the UDC in order to
e.g. allow lower power states to be achieved by
turning off unnecessary clocks and/or stoping
PHYs.

When reconnecting, call ->udc_start() again to
make sure UDC is reinitialized.
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/usb/gadget/udc-core.c

@@ -359,8 +359,12 @@ static ssize_t usb_udc_softconn_store(struct device *dev,
 	struct usb_udc		*udc = container_of(dev, struct usb_udc, dev);
 
 	if (sysfs_streq(buf, "connect")) {
+		if (udc_is_newstyle(udc))
+			usb_gadget_udc_start(udc->gadget, udc->driver);
 		usb_gadget_connect(udc->gadget);
 	} else if (sysfs_streq(buf, "disconnect")) {
+		if (udc_is_newstyle(udc))
+			usb_gadget_udc_stop(udc->gadget, udc->driver);
 		usb_gadget_disconnect(udc->gadget);
 	} else {
 		dev_err(dev, "unsupported command '%s'\n", buf);