[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>
diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c
index 4217925..66bbda7 100644
--- a/drivers/acpi/processor_core.c
+++ b/drivers/acpi/processor_core.c
@@ -253,31 +253,21 @@
* _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;
+ if (!pdc_in)
+ return_VALUE(status);
- pdc = (pdc_in) ? pdc_in : &no_object;
+ status = acpi_evaluate_object(pr->handle, "_PDC", pdc_in, NULL);
- status = acpi_evaluate_object(pr->handle, "_PDC", pdc, 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 @@
"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) {