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Colin King 07-11-2012 03:24 PM

ACPI / PM: Make acpi_pm_device_sleep_state() follow the specification
From: "Rafael J. Wysocki" <>


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 <>
Signed-off-by: Colin Ian King <>
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';

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