USB: more autosuspend timer stuff

This patch (as879) ties up some loose ends from an earlier patch.
These are things I didn't think to include at the time but which
clearly belonged there.

If an autosuspend fails because driver activity races with
the autosuspend call, restart the autosuspend timer.

When a device is resumed by an external request, it counts
as device activity and should update the last_busy time so
that the next autoresume won't occur immediately.

Signed-off-by: Alan Stern <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/core/driver.c

···
 
 #else
 
-#define autosuspend_check(udev)		0
+static inline int autosuspend_check(struct usb_device *udev)
+{
+	return 0;
+}
 
 #endif	/* CONFIG_USB_SUSPEND */
 
···
 		if (status < 0)
 			goto done;
 	}
-	cancel_delayed_work(&udev->autosuspend);
 
 	/* Suspend all the interfaces and then udev itself */
 	if (udev->actconfig) {
···
 			usb_resume_interface(intf);
 		}
 
+		/* Try another autosuspend when the interfaces aren't busy */
+		if (udev->auto_pm)
+			autosuspend_check(udev);
+
 	/* If the suspend succeeded, propagate it up the tree */
-	} else if (parent)
-		usb_autosuspend_device(parent);
+	} else {
+		cancel_delayed_work(&udev->autosuspend);
+		if (parent)
+			usb_autosuspend_device(parent);
+	}
 
  done:
 	// dev_dbg(&udev->dev, "%s: status %d\n", __FUNCTION__, status);
···
 	usb_pm_lock(udev);
 	udev->auto_pm = 0;
 	status = usb_resume_both(udev);
+	udev->last_busy = jiffies;
 	usb_pm_unlock(udev);
 
 	/* Now that the device is awake, we can start trying to autosuspend