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cpufreq: intel_pstate: Enable PPC enforcement for servers 

For platforms which are controlled via remove node manager, enable _PPC by
default. These platforms are mostly categorized as enterprise server or
performance servers. These platforms needs to go through some
certifications tests, which tests control via _PPC.
The relative risk of enabling by default is  low as this is is less likely
that these systems have broken _PSS table.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Srinivas Pandruvada 2016-04-27 15:48:08 -07:00 committed by Rafael J. Wysocki
parent 3be9200d51
commit 2b3ec76505
2 changed files with 15 additions and 2 deletions
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5
Documentation/kernel-parameters.txt
View File

@ -1662,7 +1662,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
Only load intel_pstate on systems which support
hardware P state control (HWP) if available.
support_acpi_ppc
Enforce ACPI _PPC performance limits.
Enforce ACPI _PPC performance limits. If the Fixed ACPI
Description Table, specifies preferred power management
profile as "Enterprise Server" or "Performance Server",
then this feature is turned on by default.
intremap= [X86-64, Intel-IOMMU]
on enable Interrupt Remapping (default)

12
drivers/cpufreq/intel_pstate.c
View File

@ -347,6 +347,16 @@ static struct perf_limits *limits = &powersave_limits;
#endif
#ifdef CONFIG_ACPI
static bool intel_pstate_get_ppc_enable_status(void)
{
if (acpi_gbl_FADT.preferred_profile == PM_ENTERPRISE_SERVER ||
acpi_gbl_FADT.preferred_profile == PM_PERFORMANCE_SERVER)
return true;
return acpi_ppc;
}
/*
* The max target pstate ratio is a 8 bit value in both PLATFORM_INFO MSR and
* in TURBO_RATIO_LIMIT MSR, which pstate driver stores in max_pstate and
@ -370,7 +380,7 @@ static void intel_pstate_init_acpi_perf_limits(struct cpufreq_policy *policy)
int ret;
int i;
if (!acpi_ppc)
if (!intel_pstate_get_ppc_enable_status())
return;
cpu = all_cpu_data[policy->cpu];