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[PATCH] USB: obey the sysfs power/wakeup setting

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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@xxxxxxxxxxxxxxxxxxx>
CC: stable@xxxxxxxxxx

---

Greg:

The problem this fixes is not a huge bug.  In fact, it may not affect
anybody at all.  Consequently this doesn't really need to get into
2.6.35; getting into 2.6.35.1 would be good enough.

It probably should go into 2.6.34.stable also.  However, this would
require that the earlier as1364 patch ("USB: don't enable remote wakeup
by default") go into 2.6.34.stable at the same time.  Is that okay?  
Should I resubmit that patch to stable@xxxxxxxxxx?

For 2.6.33.stable and earlier, the patch won't apply in this form; it
would need to be back-ported.  I think we don't need to worry about
those kernels.

Alan Stern



Index: usb-2.6/drivers/usb/core/driver.c
===================================================================
--- usb-2.6.orig/drivers/usb/core/driver.c
+++ usb-2.6/drivers/usb/core/driver.c
@@ -1272,8 +1272,7 @@ 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
@@ -1285,16 +1284,10 @@ 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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B and H Foto and Electronics Corp.

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