ACPI / PM: Split code validating need for runtime resume in ->prepare()

Move the code dealing with validation of whether runtime resuming the
device is needed during system suspend.

In this way it becomes more clear for what circumstances ACPI is prevented
from trying the direct_complete path.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/device_pm.c

@@ -966,6 +966,27 @@ int acpi_dev_suspend_late(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(acpi_dev_suspend_late);
 
+static bool acpi_dev_needs_resume(struct device *dev, struct acpi_device *adev)
+{
+	u32 sys_target = acpi_target_system_state();
+	int ret, state;
+
+	if (device_may_wakeup(dev) != !!adev->wakeup.prepare_count)
+		return true;
+
+	if (sys_target == ACPI_STATE_S0)
+		return false;
+
+	if (adev->power.flags.dsw_present)
+		return true;
+
+	ret = acpi_dev_pm_get_state(dev, adev, sys_target, NULL, &state);
+	if (ret)
+		return true;
+
+	return state != adev->power.state;
+}
+
 /**
  * acpi_subsys_prepare - Prepare device for system transition to a sleep state.
  * @dev: Device to prepare.
@@ -973,26 +994,16 @@ EXPORT_SYMBOL_GPL(acpi_dev_suspend_late);
 int acpi_subsys_prepare(struct device *dev)
 {
 	struct acpi_device *adev = ACPI_COMPANION(dev);
-	u32 sys_target;
-	int ret, state;
+	int ret;
 
 	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;
-
-	if (adev->power.flags.dsw_present)
+	if (!adev || !pm_runtime_suspended(dev))
 		return 0;
 
-	ret = acpi_dev_pm_get_state(dev, adev, sys_target, NULL, &state);
-	return !ret && state == adev->power.state;
+	return !acpi_dev_needs_resume(dev, adev);
 }
 EXPORT_SYMBOL_GPL(acpi_subsys_prepare);