3 files changed, 42 insertions, 8 deletions

diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
index d047739f3380..9e5fd9c440b7 100644
--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c
@@ -900,18 +900,46 @@ EXPORT_SYMBOL_GPL(acpi_dev_resume_early);
  */
 int acpi_subsys_prepare(struct device *dev)
 {
-        /*
-         * Devices having power.ignore_children set may still be necessary for
-         * suspending their children in the next phase of device suspend.
-         */
-        if (dev->power.ignore_children)
-                pm_runtime_resume(dev);
+        struct acpi_device *adev = ACPI_COMPANION(dev);
+        u32 sys_target;
+        int ret, state;
+
+        ret = pm_generic_prepare(dev);
+        if (ret < 0)
+                return ret;
+
+        if (!adev || !pm_runtime_suspended(dev)
+            || device_may_wakeup(dev) != !!adev->wakeup.prepare_count)
+                return 0;
+
+        sys_target = acpi_target_system_state();
+        if (sys_target == ACPI_STATE_S0)
+                return 1;
 
-        return pm_generic_prepare(dev);
+        if (adev->power.flags.dsw_present)
+                return 0;
+
+        ret = acpi_dev_pm_get_state(dev, adev, sys_target, NULL, &state);
+        return !ret && state == adev->power.state;
 }
 EXPORT_SYMBOL_GPL(acpi_subsys_prepare);
 
 /**
+ * acpi_subsys_complete - Finalize device's resume during system resume.
+ * @dev: Device to handle.
+ */
+static void acpi_subsys_complete(struct device *dev)
+{
+        /*
+         * If the device had been runtime-suspended before the system went into
+         * the sleep state it is going out of and it has never been resumed till
+         * now, resume it in case the firmware powered it up.
+         */
+        if (dev->power.direct_complete)
+                pm_request_resume(dev);
+}
+
+/**
  * acpi_subsys_suspend - Run the device driver's suspend callback.
  * @dev: Device to handle.
  *
@@ -979,6 +1007,7 @@ static struct dev_pm_domain acpi_general_pm_domain = {
 #endif
 #ifdef CONFIG_PM_SLEEP
                 .prepare = acpi_subsys_prepare,
+                .complete = acpi_subsys_complete,
                 .suspend = acpi_subsys_suspend,
                 .suspend_late = acpi_subsys_suspend_late,
                 .resume_early = acpi_subsys_resume_early,
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 7efe546a8c42..df6e4c924b35 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -1551,9 +1551,13 @@ static void acpi_bus_get_power_flags(struct acpi_device *device)
          */
         if (acpi_has_method(device->handle, "_PSC"))
                 device->power.flags.explicit_get = 1;
+
         if (acpi_has_method(device->handle, "_IRC"))
                 device->power.flags.inrush_current = 1;
 
+        if (acpi_has_method(device->handle, "_DSW"))
+                device->power.flags.dsw_present = 1;
+
         /*
          * Enumerate supported power management states
          */
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 84a2e29a2314..7417a16c8d86 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -261,7 +261,8 @@ struct acpi_device_power_flags {
         u32 inrush_current:1;   /* Serialize Dx->D0 */
         u32 power_removed:1;    /* Optimize Dx->D0 */
         u32 ignore_parent:1;    /* Power is independent of parent power state */
-        u32 reserved:27;
+        u32 dsw_present:1;      /* _DSW present? */
+        u32 reserved:26;
 };
 
 struct acpi_device_power_state {