ACPI processor: introduce module parameter processor.ignore_tpc

Introduce module parameter processor.ignore_tpc.

Some laptops are shipped with buggy _TPC,
this module parameter is used to to disable the buggy support.

http://bugzilla.kernel.org/show_bug.cgi?id=13259

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Tested-by: James Ettle <theholyettlz@googlemail.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/drivers/acpi/processor_throttling.c b/drivers/acpi/processor_throttling.c
index d0d1f4d50434..5f09fb8c0e05 100644
--- a/drivers/acpi/processor_throttling.c
+++ b/drivers/acpi/processor_throttling.c
@@ -45,6 +45,14 @@
 #define _COMPONENT              ACPI_PROCESSOR_COMPONENT
 ACPI_MODULE_NAME("processor_throttling");
 
+/* ignore_tpc:
+ *  0 -> acpi processor driver doesn't ignore _TPC values
+ *  1 -> acpi processor driver ignores _TPC values
+ */
+static int ignore_tpc;
+module_param(ignore_tpc, int, 0644);
+MODULE_PARM_DESC(ignore_tpc, "Disable broken BIOS _TPC throttling support");
+
 struct throttling_tstate {
         unsigned int cpu;               /* cpu nr */
         int target_state;               /* target T-state */
@@ -283,6 +291,10 @@ static int acpi_processor_get_platform_limit(struct acpi_processor *pr)
 
         if (!pr)
                 return -EINVAL;
+
+        if (ignore_tpc)
+                goto end;
+
         status = acpi_evaluate_integer(pr->handle, "_TPC", NULL, &tpc);
         if (ACPI_FAILURE(status)) {
                 if (status != AE_NOT_FOUND) {
@@ -290,6 +302,8 @@ static int acpi_processor_get_platform_limit(struct acpi_processor *pr)
                 }
                 return -ENODEV;
         }
+
+end:
         pr->throttling_platform_limit = (int)tpc;
         return 0;
 }
@@ -302,6 +316,9 @@ int acpi_processor_tstate_has_changed(struct acpi_processor *pr)
         struct acpi_processor_limit *limit;
         int target_state;
 
+        if (ignore_tpc)
+                return 0;
+
         result = acpi_processor_get_platform_limit(pr);
         if (result) {
                 /* Throttling Limit is unsupported */