1 files changed, 52 insertions, 4 deletions

diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c
index 01e366d2b6fb..a959f6a07508 100644
--- a/drivers/acpi/processor_perflib.c
+++ b/drivers/acpi/processor_perflib.c
@@ -152,15 +152,59 @@ static int acpi_processor_get_platform_limit(struct acpi_processor *pr)
 	return 0;
 }
 
-int acpi_processor_ppc_has_changed(struct acpi_processor *pr)
+#define ACPI_PROCESSOR_NOTIFY_PERFORMANCE	0x80
+/*
+ * acpi_processor_ppc_ost: Notify firmware the _PPC evaluation status
+ * @handle: ACPI processor handle
+ * @status: the status code of _PPC evaluation
+ *	0: success. OSPM is now using the performance state specificed.
+ *	1: failure. OSPM has not changed the number of P-states in use
+ */
+static void acpi_processor_ppc_ost(acpi_handle handle, int status)
+{
+	union acpi_object params[2] = {
+		{.type = ACPI_TYPE_INTEGER,},
+		{.type = ACPI_TYPE_INTEGER,},
+	};
+	struct acpi_object_list arg_list = {2, params};
+	acpi_handle temp;
+
+	params[0].integer.value = ACPI_PROCESSOR_NOTIFY_PERFORMANCE;
+	params[1].integer.value =  status;
+
+	/* when there is no _OST , skip it */
+	if (ACPI_FAILURE(acpi_get_handle(handle, "_OST", &temp)))
+		return;
+
+	acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
+	return;
+}
+
+int acpi_processor_ppc_has_changed(struct acpi_processor *pr, int event_flag)
 {
 	int ret;
 
-	if (ignore_ppc)
+	if (ignore_ppc) {
+		/*
+		 * Only when it is notification event, the _OST object
+		 * will be evaluated. Otherwise it is skipped.
+		 */
+		if (event_flag)
+			acpi_processor_ppc_ost(pr->handle, 1);
 		return 0;
+	}
 
 	ret = acpi_processor_get_platform_limit(pr);
-
+	/*
+	 * Only when it is notification event, the _OST object
+	 * will be evaluated. Otherwise it is skipped.
+	 */
+	if (event_flag) {
+		if (ret < 0)
+			acpi_processor_ppc_ost(pr->handle, 1);
+		else
+			acpi_processor_ppc_ost(pr->handle, 0);
+	}
 	if (ret < 0)
 		return (ret);
 	else
@@ -369,7 +413,11 @@ static int acpi_processor_get_performance_info(struct acpi_processor *pr)
 	if (result)
 		goto update_bios;
 
-	return 0;
+	/* We need to call _PPC once when cpufreq starts */
+	if (ignore_ppc != 1)
+		result = acpi_processor_get_platform_limit(pr);
+
+	return result;
 
 	/*
 	 * Having _PPC but missing frequencies (_PSS, _PCT) is a very good hint that