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 <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>
Acked-by: Srinivas Pandruvada <[email protected]>
This commit is contained in:
Rafael J. Wysocki 2016-11-17 22:47:47 +01:00
commit d0ea59e188
3 changed files with 42 additions and 17 deletions

View file

@ -249,6 +249,7 @@ extern int acpi_processor_register_performance(struct acpi_processor_performance
*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);