usbnet: Support devices reporting idleness

Some device types support a form of power management in which
the device suggests to the host that the device may be suspended
now. Support for that is best located in usbnet.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/usb/cdc_eem.c

@@ -244,8 +244,12 @@ static int eem_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 			 *  - suspend: peripheral ready to suspend
 			 *  - response: suggest N millisec polling
 			 *  - response complete: suggest N sec polling
+			 *
+			 * Suspend is reported and maybe heeded.
 			 */
 			case 2:		/* Suspend hint */
+				usbnet_device_suggests_idle(dev);
+				continue;
 			case 3:		/* Response hint */
 			case 4:		/* Response complete hint */
 				continue;

drivers/net/usb/usbnet.c

@@ -1588,10 +1588,27 @@ int usbnet_resume (struct usb_interface *intf)
 			tasklet_schedule (&dev->bh);
 		}
 	}
+
+	if (test_and_clear_bit(EVENT_DEVICE_REPORT_IDLE, &dev->flags))
+		usb_autopm_get_interface_no_resume(intf);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(usbnet_resume);
 
+/*
+ * Either a subdriver implements manage_power, then it is assumed to always
+ * be ready to be suspended or it reports the readiness to be suspended
+ * explicitly
+ */
+void usbnet_device_suggests_idle(struct usbnet *dev)
+{
+	if (!test_and_set_bit(EVENT_DEVICE_REPORT_IDLE, &dev->flags)) {
+		dev->intf->needs_remote_wakeup = 1;
+		usb_autopm_put_interface_async(dev->intf);
+	}
+}
+EXPORT_SYMBOL(usbnet_device_suggests_idle);
 
 /*-------------------------------------------------------------------------*/
 

include/linux/usb/usbnet.h

@@ -68,6 +68,7 @@ struct usbnet {
 #		define EVENT_RX_PAUSED	5
 #		define EVENT_DEV_ASLEEP 6
 #		define EVENT_DEV_OPEN	7
+#		define EVENT_DEVICE_REPORT_IDLE	8
 };
 
 static inline struct usb_driver *driver_of(struct usb_interface *intf)
@@ -160,6 +161,7 @@ extern int usbnet_probe(struct usb_interface *, const struct usb_device_id *);
 extern int usbnet_suspend(struct usb_interface *, pm_message_t);
 extern int usbnet_resume(struct usb_interface *);
 extern void usbnet_disconnect(struct usb_interface *);
+extern void usbnet_device_suggests_idle(struct usbnet *dev);
 
 
 /* Drivers that reuse some of the standard USB CDC infrastructure