USB: fix remote wakeup settings during system sleep

This patch (as1363) changes the way USB remote wakeup is handled
during system sleeps.  It won't be enabled unless an interface driver
specifically needs it.  Also, it won't be enabled during the FREEZE or
QUIESCE phases of hibernation, when the system doesn't respond to
wakeup events anyway.  Finally, if the device is already
runtime-suspended with remote wakeup enabled, but wakeup is supposed
to be disabled for the system sleep, the device gets woken up so that
it can be suspended again with the proper wakeup setting.

This will fix problems people have reported with certain USB webcams
that generate wakeup requests when they shouldn't, and as a result
cause system suspends to fail.  See

	https://bugs.launchpad.net/ubuntu/+source/linux/+bug/515109

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Erik Andrén <erik.andren@gmail.com>
CC: <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/driver.c

@@ -1263,13 +1263,47 @@ static int usb_resume_both(struct usb_device *udev, pm_message_t msg)
 	return status;
 }
 
+static void choose_wakeup(struct usb_device *udev, pm_message_t msg)
+{
+	int			w, i;
+	struct usb_interface	*intf;
+
+	/* Remote wakeup is needed only when we actually go to sleep.
+	 * For things like FREEZE and QUIESCE, if the device is already
+	 * autosuspended then its current wakeup setting is okay.
+	 */
+	if (msg.event == PM_EVENT_FREEZE || msg.event == PM_EVENT_QUIESCE) {
+		if (udev->state != USB_STATE_SUSPENDED)
+			udev->do_remote_wakeup = 0;
+		return;
+	}
+
+	/* If remote wakeup is permitted, see whether any interface drivers
+	 * actually want it.
+	 */
+	w = 0;
+	if (device_may_wakeup(&udev->dev) && udev->actconfig) {
+		for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {
+			intf = udev->actconfig->interface[i];
+			w |= intf->needs_remote_wakeup;
+		}
+	}
+
+	/* If the device is autosuspended with the wrong wakeup setting,
+	 * autoresume now so the setting can be changed.
+	 */
+	if (udev->state == USB_STATE_SUSPENDED && w != udev->do_remote_wakeup)
+		pm_runtime_resume(&udev->dev);
+	udev->do_remote_wakeup = w;
+}
+
 /* The device lock is held by the PM core */
 int usb_suspend(struct device *dev, pm_message_t msg)
 {
 	struct usb_device	*udev = to_usb_device(dev);
 
 	do_unbind_rebind(udev, DO_UNBIND);
-	udev->do_remote_wakeup = device_may_wakeup(&udev->dev);
+	choose_wakeup(udev, msg);
 	return usb_suspend_both(udev, msg);
 }