[ACPI] Avoid BIOS inflicted crashes by evaluating _PDC only once

Linux invokes the AML _PDC method (Processor Driver Capabilities)
to tell the BIOS what features it can handle.  While the ACPI
spec says nothing about the OS invoking _PDC multiple times,
doing so with changing bits seems to hopelessly confuse the BIOS
on multiple platforms up to and including crashing the system.

Factor out the _PDC invocation so Linux invokes it only once.

http://bugzilla.kernel.org/show_bug.cgi?id=5483

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

3 files changed, 11 insertions, 21 deletions

diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c
index 421792562642..66bbda78507a 100644
--- a/drivers/acpi/processor_core.c
+++ b/drivers/acpi/processor_core.c
@@ -253,31 +253,21 @@ static int acpi_processor_errata(struct acpi_processor *pr)
  * _PDC is required for a BIOS-OS handshake for most of the newer
  * ACPI processor features.
  */
-
-int acpi_processor_set_pdc(struct acpi_processor *pr,
-			   struct acpi_object_list *pdc_in)
+static int acpi_processor_set_pdc(struct acpi_processor *pr)
 {
+	struct acpi_object_list *pdc_in = pr->pdc;
 	acpi_status status = AE_OK;
-	u32 arg0_buf[3];
-	union acpi_object arg0 = { ACPI_TYPE_BUFFER };
-	struct acpi_object_list no_object = { 1, &arg0 };
-	struct acpi_object_list *pdc;
 
 	ACPI_FUNCTION_TRACE("acpi_processor_set_pdc");
 
-	arg0.buffer.length = 12;
-	arg0.buffer.pointer = (u8 *) arg0_buf;
-	arg0_buf[0] = ACPI_PDC_REVISION_ID;
-	arg0_buf[1] = 0;
-	arg0_buf[2] = 0;
-
-	pdc = (pdc_in) ? pdc_in : &no_object;
+	if (!pdc_in)
+		return_VALUE(status);
 
-	status = acpi_evaluate_object(pr->handle, "_PDC", pdc, NULL);
+	status = acpi_evaluate_object(pr->handle, "_PDC", pdc_in, NULL);
 
-	if ((ACPI_FAILURE(status)) && (pdc_in))
+	if (ACPI_FAILURE(status))
 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
-				  "Error evaluating _PDC, using legacy perf. control...\n"));
+		    "Could not evaluate _PDC, using legacy perf. control...\n"));
 
 	return_VALUE(status);
 }
@@ -574,6 +564,10 @@ static int acpi_processor_start(struct acpi_device *device)
 				  "Error installing device notify handler\n"));
 	}
 
+	/* _PDC call should be done before doing anything else (if reqd.). */
+	arch_acpi_processor_init_pdc(pr);
+	acpi_processor_set_pdc(pr);
+
 	acpi_processor_power_init(pr, device);
 
 	if (pr->flags.throttling) {
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 70d8a6ec0920..1915c377bfc6 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -1014,8 +1014,6 @@ int acpi_processor_power_init(struct acpi_processor *pr,
 		}
 	}
 
-	acpi_processor_power_init_pdc(&(pr->power), pr->id);
-	acpi_processor_set_pdc(pr, pr->power.pdc);
 	acpi_processor_get_power_info(pr);
 
 	/*
diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c
index 22c7bb66c200..532370734c68 100644
--- a/drivers/acpi/processor_perflib.c
+++ b/drivers/acpi/processor_perflib.c
@@ -315,8 +315,6 @@ static int acpi_processor_get_performance_info(struct acpi_processor *pr)
 	if (!pr || !pr->performance || !pr->handle)
 		return_VALUE(-EINVAL);
 
-	acpi_processor_set_pdc(pr, pr->performance->pdc);
-
 	status = acpi_get_handle(pr->handle, "_PCT", &handle);
 	if (ACPI_FAILURE(status)) {
 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,