Find the ACPI power resource object and put it into OFF state before
scanning ACPI device tree

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
---
 drivers/acpi/scan.c |   37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

Index: linux-2.6/drivers/acpi/scan.c
===================================================================
--- linux-2.6.orig/drivers/acpi/scan.c	2009-04-20 09:13:37.000000000 +0800
+++ linux-2.6/drivers/acpi/scan.c	2009-05-04 09:40:56.000000000 +0800
@@ -1575,6 +1575,37 @@
 
 	return result;
 }
+/*
+ * Find the power resource and turn off the power resource by calling the
+ * _OFF object
+ */
+static acpi_status
+find_and_power_off(acpi_handle handle, u32 level, void *context,
+		   void **return_value)
+{
+	char bus_id[5];
+	acpi_handle dummy_handle;
+	struct acpi_buffer buffer = {sizeof(bus_id), bus_id};
+
+	acpi_get_name(handle, ACPI_SINGLE_NAME, &buffer);
+
+	/*
+	 * check whether there exists the _ON/_OFF object for the power
+	 * resource. If it doesn't exists, it will be regarded as a bogus
+	 * power resource object.
+	 */
+	if (ACPI_FAILURE(acpi_get_handle(handle, "_ON", &dummy_handle)) ||
+	    ACPI_FAILURE(acpi_get_handle(handle, "_OFF", &dummy_handle))) {
+		printk(KERN_INFO " bogus power resource[%s] is found\n",
+				bus_id);
+		return AE_OK;
+	}
+	/* Power off the power resource object by evaluating the _OFF */
+	acpi_evaluate_object(handle, "_OFF", NULL, NULL);
+	ACPI_DEBUG_PRINT((ACPI_DB_INFO, " power resource [%s] is off",
+				bus_id));
+	return AE_OK;
+}
 
 int __init acpi_scan_init(void)
 {
@@ -1585,6 +1616,12 @@
 	ops.acpi_op_add = 1;
 	ops.acpi_op_start = 1;
 
+	/*
+	 * Find the power resource object and put it into OFF state.
+	 */
+	acpi_walk_namespace(ACPI_TYPE_POWER, ACPI_ROOT_OBJECT, ACPI_UINT32_MAX,
+			    find_and_power_off, NULL, NULL);
+
 	result = bus_register(&acpi_bus_type);
 	if (result) {
 		/* We don't want to quit even if we failed to add suspend/resume */