ACPI: processor: call _PDC early

We discovered that at least one machine (HP Envy), methods in the DSDT
attempt to call external methods defined in a dynamically loaded SSDT.

Unfortunately, the DSDT methods we are trying to call are part of the
EC initialization, which happens very early, and the the dynamic SSDT
is only loaded when a processor _PDC method runs much later.

This results in namespace lookup errors for the (as of yet) undefined
methods.

Since Windows doesn't have any issues with this machine, we take it
as a hint that they must be evaluating _PDC much earlier than we are.

Thus, the proper thing for Linux to do should be to match the Windows
implementation more closely.

Provide a mechanism to call _PDC before we enable the EC. Doing so loads
the dynamic tables, and allows the EC to be enabled correctly.

The ACPI processor driver will still evaluate _PDC in its .add() method
to cover the hotplug case.

Resolves: http://bugzilla.kernel.org/show_bug.cgi?id=14824

Cc: ming.m.lin@intel.com
Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/acpi/processor.h b/include/acpi/processor.h
index 29245c6b5c0e..a1b748a7a766 100644
--- a/include/acpi/processor.h
+++ b/include/acpi/processor.h
@@ -325,6 +325,9 @@ static inline int acpi_processor_get_bios_limit(int cpu, unsigned int *limit)
 
 #endif                          /* CONFIG_CPU_FREQ */
 
+/* in processor_pdc.c */
+void acpi_processor_set_pdc(struct acpi_processor *pr);
+
 /* in processor_throttling.c */
 int acpi_processor_tstate_has_changed(struct acpi_processor *pr);
 int acpi_processor_get_throttling_info(struct acpi_processor *pr);