ACPI: scan: Obtain device's desired enumeration power state

Store a device's desired enumeration power state in struct
acpi_device_power during acpi_device object's initialisation.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/scan.c

@@ -1017,6 +1017,7 @@ static void acpi_bus_init_power_state(struct acpi_device *device, int state)
 
 static void acpi_bus_get_power_flags(struct acpi_device *device)
 {
+	unsigned long long dsc = ACPI_STATE_D0;
 	u32 i;
 
 	/* Presence of _PS0|_PR0 indicates 'power manageable' */
@@ -1038,6 +1039,9 @@ static void acpi_bus_get_power_flags(struct acpi_device *device)
 	if (acpi_has_method(device->handle, "_DSW"))
 		device->power.flags.dsw_present = 1;
 
+	acpi_evaluate_integer(device->handle, "_DSC", NULL, &dsc);
+	device->power.state_for_enumeration = dsc;
+
 	/*
 	 * Enumerate supported power management states
 	 */

include/acpi/acpi_bus.h

@@ -278,6 +278,7 @@ struct acpi_device_power {
 	int state;		/* Current state */
 	struct acpi_device_power_flags flags;
 	struct acpi_device_power_state states[ACPI_D_STATE_COUNT];	/* Power states (D0-D3Cold) */
+	u8 state_for_enumeration; /* Deepest power state for enumeration */
 };
 
 struct acpi_dep_data {