[PATCH 1/1] ACPI / PM: Make acpi_pm_device_sleep_state() follow the specification

[Colin King]

From: "Rafael J. Wysocki" <rjw at sisk.pl>

BugLink: http://bugs.launchpad.net/bugs/904261

The comparison between the system sleep state being entered
and the lowest system sleep state the given device may wake up
from in acpi_pm_device_sleep_state() is reversed, because the
specification (ACPI 5.0) says that for wakeup to work:

"The sleeping state being entered must be less than or equal to the
 power state declared in element 1 of the _PRW object."

In other words, the state returned by _PRW is the deepest
(lowest-power) system sleep state the device is capable of waking up
the system from.

Moreover, acpi_pm_device_sleep_state() also should check if the
wakeup capability is supported through ACPI, because in principle it
may be done via native PCIe PME, for example, in which case _SxW
should not be evaluated.

Signed-off-by: Rafael J. Wysocki <rjw at sisk.pl>
Signed-off-by: Colin Ian King <colin.king at canonical.com>
---
 drivers/acpi/sleep.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
index ca191ff..ed6bc52 100644
--- a/drivers/acpi/sleep.c
+++ b/drivers/acpi/sleep.c
@@ -702,8 +702,8 @@ int acpi_pm_device_sleep_state(struct device *dev, int *d_min_p)
 	 * can wake the system.  _S0W may be valid, too.
 	 */
 	if (acpi_target_sleep_state == ACPI_STATE_S0 ||
-	    (device_may_wakeup(dev) &&
-	     adev->wakeup.sleep_state <= acpi_target_sleep_state)) {
+	    (device_may_wakeup(dev) && adev->wakeup.flags.valid &&
+	     adev->wakeup.sleep_state >= acpi_target_sleep_state)) {
 		acpi_status status;
 
 		acpi_method[3] = 'W';
-- 
1.7.9.5