linux-kernel - [129/205] USB: obey the sysfs power/wakeup setting

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Date:	Fri, 30 Jul 2010 10:52:26 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Alan Stern <stern@...land.harvard.edu>
Subject: [129/205] USB: obey the sysfs power/wakeup setting

2.6.34-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Alan Stern <stern@...land.harvard.edu>

commit 48826626263d4a61d06fd8c5805da31f925aefa0 upstream.

This patch (as1403) is a partial reversion of an earlier change
(commit 5f677f1d45b2bf08085bbba7394392dfa586fa8e "USB: fix remote
wakeup settings during system sleep").  After hearing from a user, I
realized that remote wakeup should be enabled during system sleep
whenever userspace allows it, and not only if a driver requests it
too.

Indeed, there could be a device with no driver, that does nothing but
generate a wakeup request when the user presses a button.  Such a
device should be allowed to do its job.

The problem fixed by the earlier patch -- device generating a wakeup
request for no reason, causing system suspend to abort -- was also
addressed by a later patch ("USB: don't enable remote wakeup by
default", accepted but not yet merged into mainline).  The device
won't be able to generate the bogus wakeup requests because it will be
disabled for remote wakeup by default.  Hence this reversion will not
re-introduce any old problems.

Signed-off-by: Alan Stern <stern@...land.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/usb/core/driver.c |   13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -1266,8 +1266,7 @@ static int usb_resume_both(struct usb_de

 static void choose_wakeup(struct usb_device *udev, pm_message_t msg)
 {
-	int			w, i;
-	struct usb_interface	*intf;
+	int	w;

 	/* Remote wakeup is needed only when we actually go to sleep.
 	 * For things like FREEZE and QUIESCE, if the device is already
@@ -1279,16 +1278,10 @@ static void choose_wakeup(struct usb_dev
 		return;
 	}

-	/* If remote wakeup is permitted, see whether any interface drivers
+	/* Enable remote wakeup if it is allowed, even if no 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;
-		}
-	}
+	w = device_may_wakeup(&udev->dev);

 	/* If the device is autosuspended with the wrong wakeup setting,
 	 * autoresume now so the setting can be changed.

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