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-rw-r--r--Documentation/kernel-parameters.txt3
-rw-r--r--drivers/cpufreq/intel_pstate.c6
2 files changed, 9 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 4df73da11adc..07e6701a1439 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1469,6 +1469,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
no_hwp
Do not enable hardware P state control (HWP)
if available.
+ hwp_only
+ Only load intel_pstate on systems which support
+ hardware P state control (HWP) if available.
intremap= [X86-64, Intel-IOMMU]
on enable Interrupt Remapping (default)
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index e7e808d9a8af..872c5772c5d3 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -1019,6 +1019,7 @@ static struct cpufreq_driver intel_pstate_driver = {
static int __initdata no_load;
static int __initdata no_hwp;
+static int __initdata hwp_only;
static unsigned int force_load;
static int intel_pstate_msrs_not_valid(void)
@@ -1216,6 +1217,9 @@ static int __init intel_pstate_init(void)
if (cpu_has(c,X86_FEATURE_HWP) && !no_hwp)
intel_pstate_hwp_enable();
+ if (!hwp_active && hwp_only)
+ goto out;
+
rc = cpufreq_register_driver(&intel_pstate_driver);
if (rc)
goto out;
@@ -1250,6 +1254,8 @@ static int __init intel_pstate_setup(char *str)
no_hwp = 1;
if (!strcmp(str, "force"))
force_load = 1;
+ if (!strcmp(str, "hwp_only"))
+ hwp_only = 1;
return 0;
}
early_param("intel_pstate", intel_pstate_setup);