PM: Update the policy on default wakeup settings

This patch (as1485) documents a change to the kernel's default wakeup
policy.  Devices that forward wakeup requests between buses should be
enabled for wakeup by default.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
index 84f7c7d..14ee07e 100644
--- a/drivers/base/power/wakeup.c
+++ b/drivers/base/power/wakeup.c
@@ -276,7 +276,9 @@
  *
  * By default, most devices should leave wakeup disabled.  The exceptions are
  * devices that everyone expects to be wakeup sources: keyboards, power buttons,
- * possibly network interfaces, etc.
+ * possibly network interfaces, etc.  Also, devices that don't generate their
+ * own wakeup requests but merely forward requests from one bus to another
+ * (like PCI bridges) should have wakeup enabled by default.
  */
 int device_init_wakeup(struct device *dev, bool enable)
 {