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>

Documentation/power/devices.txt

@@ -152,7 +152,9 @@ try to use its wakeup mechanism.  device_set_wakeup_enable() affects this flag;
 for the most part drivers should not change its value.  The initial value of
 should_wakeup is supposed to be false for the majority of devices; the major
 exceptions are power buttons, keyboards, and Ethernet adapters whose WoL
-(wake-on-LAN) feature has been set up with ethtool.
+(wake-on-LAN) feature has been set up with ethtool.  It should also default
+to true for devices that don't generate wakeup requests on their own but merely
+forward wakeup requests from one bus to another (like PCI bridges).
 
 Whether or not a device is capable of issuing wakeup events is a hardware
 matter, and the kernel is responsible for keeping track of it.  By contrast,

drivers/base/power/wakeup.c

@@ -276,7 +276,9 @@ EXPORT_SYMBOL_GPL(device_set_wakeup_capable);
  *
  * 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)
 {