1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index 4edff1738579..d77c2307883c 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -212,6 +212,12 @@ acpi_bus_set_power (
                 ACPI_DEBUG_PRINT((ACPI_DB_WARN, "Device is not power manageable\n"));
                 return_VALUE(-ENODEV);
         }
+        /*
+         * Get device's current power state if it's unknown
+         * This means device power state isn't initialized or previous setting failed
+         */
+        if (device->power.state == ACPI_STATE_UNKNOWN)
+                acpi_bus_get_power(device->handle, &device->power.state);
         if (state == device->power.state) {
                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device is already at D%d\n", state));
                 return_VALUE(0);
@@ -231,7 +237,7 @@ acpi_bus_set_power (
          * On transitions to a high-powered state we first apply power (via
          * power resources) then evalute _PSx.  Conversly for transitions to
          * a lower-powered state.
-         */ 
+         */
         if (state < device->power.state) {
                 if (device->power.flags.power_resources) {
                         result = acpi_power_transition(device, state);