ACPI PM: Replace wakeup.prepared with reference counter

The wakeup.prepared flag is used for marking devices that have the
wake-up power already enabled, so that the wake-up power is not
enabled twice in a row for the same device.  This assumes, however,
that device wake-up power will only be enabled once, while the device
is being prepared for a system-wide sleep transition, and the second
attempt is made by acpi_enable_wakeup_device_prep().

With the upcoming PCI wake-up rework this assumption will not hold
any more for PCI bridges and the root bridge whose wake-up power
may be enabled as a result of wake-up enable propagation from other
devices (eg. add-on devices that are not associated with any GPEs).
Thus, there may be many attempts to enable wake-up power on a PCI
bridge or the root bridge during a system power state transition
and it's better to replace wakeup.prepared with a reference counter.

Reviewed-by: Matthew Garrett <mjg59@srcf.ucam.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 781435d7e369..318b1ea7a5bf 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -781,6 +781,7 @@ static int acpi_bus_get_wakeup_device_flags(struct acpi_device *device)
         kfree(buffer.pointer);
 
         device->wakeup.flags.valid = 1;
+        device->wakeup.prepare_count = 0;
         /* Call _PSW/_DSW object to disable its ability to wake the sleeping
          * system for the ACPI device with the _PRW object.
          * The _PSW object is depreciated in ACPI 3.0 and is replaced by _DSW.