cpufreq: intel_pstate: Request P-states control from SMM if needed
Currently, intel_pstate is unable to control P-states on my
IvyBridge-based Acer Aspire S5, because they are controlled by SMM
on that machine by default and it is necessary to request OS control
of P-states from it via the SMI Command register exposed in the ACPI
FADT. intel_pstate doesn't do that now, but acpi-cpufreq and other
cpufreq drivers for x86 platforms do.
Address this problem by making intel_pstate use the ACPI-defined
mechanism as well. However, intel_pstate is not modular and it
doesn't need the module refcount tricks played by
acpi_processor_notify_smm(), so export the core of this function
to it as acpi_processor_pstate_control() and make it call that.
[The changes in processor_perflib.c related to this should not
make any functional difference for the acpi_processor_notify_smm()
users].
To be safe, only call acpi_processor_notify_smm() from intel_pstate
if ACPI _PPC support is enabled in it.
Suggested-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
diff --git a/include/acpi/processor.h b/include/acpi/processor.h
index f3db11c..dd0cb04 100644
--- a/include/acpi/processor.h
+++ b/include/acpi/processor.h
@@ -249,6 +249,7 @@
*performance, unsigned int cpu);
extern void acpi_processor_unregister_performance(unsigned int cpu);
+int acpi_processor_pstate_control(void);
/* note: this locks both the calling module and the processor module
if a _PPC object exists, rmmod is disallowed then */
int acpi_processor_notify_smm(struct module *calling_module);