USB-RNDIS: Send RNDIS state on disconnecting

Add waiting for receiving Ethernet gadget state on the Windows host
side before dropping pullup, but keep it for debug.

Signed-off-by: Vitaly Kuzmichev <vkuzmichev@mvista.com>

drivers/usb/gadget/ether.c

@@ -1921,10 +1921,22 @@ static void eth_start(struct eth_dev *dev, gfp_t gfp_flags)
 
 static int eth_stop(struct eth_dev *dev)
 {
+#ifdef RNDIS_COMPLETE_SIGNAL_DISCONNECT
+	unsigned long ts;
+	unsigned long timeout = CONFIG_SYS_HZ; /* 1 sec to stop RNDIS */
+#endif
+
 	if (rndis_active(dev)) {
 		rndis_set_param_medium(dev->rndis_config, NDIS_MEDIUM_802_3, 0);
 		rndis_signal_disconnect(dev->rndis_config);
 
+#ifdef RNDIS_COMPLETE_SIGNAL_DISCONNECT
+		/* Wait until host receives OID_GEN_MEDIA_CONNECT_STATUS */
+		ts = get_timer(0);
+		while (get_timer(ts) < timeout)
+			usb_gadget_handle_interrupts();
+#endif
+
 		rndis_uninit(dev->rndis_config);
 		dev->rndis = 0;
 	}
@@ -2486,6 +2498,17 @@ void usb_eth_halt(struct eth_device *netdev)
 	if (!dev->gadget)
 		return;
 
+	/*
+	 * Some USB controllers may need additional deinitialization here
+	 * before dropping pull-up (also due to hardware issues).
+	 * For example: unhandled interrupt with status stage started may
+	 * bring the controller to fully broken state (until board reset).
+	 * There are some variants to debug and fix such cases:
+	 * 1) In the case of RNDIS connection eth_stop can perform additional
+	 * interrupt handling. See RNDIS_COMPLETE_SIGNAL_DISCONNECT definition.
+	 * 2) 'pullup' callback in your UDC driver can be improved to perform
+	 * this deinitialization.
+	 */
 	eth_stop(dev);
 
 	usb_gadget_disconnect(dev->gadget);

drivers/usb/gadget/rndis.c

@@ -995,7 +995,12 @@ int rndis_signal_disconnect(int configNr)
 	rndis_per_dev_params[configNr].media_state
 			= NDIS_MEDIA_STATE_DISCONNECTED;
 
+#ifdef RNDIS_COMPLETE_SIGNAL_DISCONNECT
+	return rndis_indicate_status_msg(configNr,
+					  RNDIS_STATUS_MEDIA_DISCONNECT);
+#else
 	return 0;
+#endif
 }
 
 void rndis_uninit(int configNr)

drivers/usb/gadget/rndis.h

@@ -17,6 +17,14 @@
 
 #include "ndis.h"
 
+/*
+ * By default rndis_signal_disconnect does not send status message about
+ * RNDIS disconnection to USB host (indicated as cable disconnected).
+ * Define RNDIS_COMPLETE_SIGNAL_DISCONNECT to send it.
+ * However, this will cause 1 sec delay on Ethernet device halt.
+ * Usually you do not need to define it. Mostly usable for debugging.
+ */
+
 #define RNDIS_MAXIMUM_FRAME_SIZE	1518
 #define RNDIS_MAX_TOTAL_SIZE		1558