[media] dvb_usb_v2: do not release USB interface when device reconnects

USB core will call disconnect and remove driver for us as device
will disconnect itself. After that it is loaded again as a new
device but it is warm and no firmware loading needed.
Reported-by: NMalcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: NAntti Palosaari <crope@iki.fi>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/dvb/dvb-usb/dvb_usb_init.c

@@ -431,11 +431,24 @@ static void dvb_usbv2_init_work(struct work_struct *work)
 				KBUILD_MODNAME, d->name);
 		ret = dvb_usbv2_download_firmware(d);
 		if (ret == 0) {
+			/* device is warm, continue initialization */
 			;
 		} else if (ret == RECONNECTS_USB) {
-			ret = 0;
-			goto exit_usb_driver_release_interface;
+			/*
+			 * USB core will call disconnect() and then probe()
+			 * as device reconnects itself from the USB bus.
+			 * disconnect() will release all driver resources
+			 * and probe() is called for 'new' device. As 'new'
+			 * device is warm we should never go here again.
+			 */
+			return;
 		} else {
+			/* Unexpected fatal error. We must unregister driver
+			 * manually from the device, because device is already
+			 * register by returning from probe() with success.
+			 * usb_driver_release_interface() finally calls
+			 * disconnect() in order to free resources.
+			 */
 			goto err_usb_driver_release_interface;
 		}
 	}
@@ -453,8 +466,7 @@ static void dvb_usbv2_init_work(struct work_struct *work)
 err_usb_driver_release_interface:
 	pr_info("%s: '%s' error while loading driver (%d)\n", KBUILD_MODNAME,
 			d->name, ret);
-exit_usb_driver_release_interface:
-	/* it finally calls .disconnect() which frees mem */
+	/* it finally calls disconnect() which frees mem */
 	usb_driver_release_interface(to_usb_driver(d->intf->dev.driver),
 			d->intf);
 	pr_debug("%s: failed=%d\n", __func__, ret);