1 files changed, 18 insertions, 5 deletions

diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
index e9e8bb24785b..4ab807dc8518 100644
--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c
@@ -324,14 +324,27 @@ int acpi_bus_update_power(acpi_handle handle, int *state_p)
         if (result)
                 return result;
 
-        if (state == ACPI_STATE_UNKNOWN)
+        if (state == ACPI_STATE_UNKNOWN) {
                 state = ACPI_STATE_D0;
-
-        result = acpi_device_set_power(device, state);
-        if (!result && state_p)
+                result = acpi_device_set_power(device, state);
+                if (result)
+                        return result;
+        } else {
+                if (device->power.flags.power_resources) {
+                        /*
+                         * We don't need to really switch the state, bu we need
+                         * to update the power resources' reference counters.
+                         */
+                        result = acpi_power_transition(device, state);
+                        if (result)
+                                return result;
+                }
+                device->power.state = state;
+        }
+        if (state_p)
                 *state_p = state;
 
-        return result;
+        return 0;
 }
 EXPORT_SYMBOL_GPL(acpi_bus_update_power);