diff options
| author | Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> | 2015-10-15 12:34:21 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-11-09 14:33:39 -0800 |
| commit | 82696471b9c72e4b996e009bb6b4ee432c175582 (patch) | |
| tree | fbdf86df598ee299b4cd377fce89bdb073793ea6 | |
| parent | 5a52c0e04133b418583244918b3fda8bd3b87d43 (diff) | |
cpufreq: intel_pstate: Fix divide by zero on Knights Landing (KNL)
commit 8e601a9f97a00bab031980de34f9a81891c1f82f upstream.
This is a workaround for KNL platform, where in some cases MPERF counter
will not have updated value before next read of MSR_IA32_MPERF. In this
case divide by zero will occur. This change ignores current sample for
busy calculation in this case.
Fixes: b34ef932d79a (intel_pstate: Knights Landing support)
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Acked-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/cpufreq/intel_pstate.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index e8d16997c5cb..1ee2ab58e37d 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -761,6 +761,11 @@ static inline void intel_pstate_sample(struct cpudata *cpu) local_irq_save(flags); rdmsrl(MSR_IA32_APERF, aperf); rdmsrl(MSR_IA32_MPERF, mperf); + if (cpu->prev_mperf == mperf) { + local_irq_restore(flags); + return; + } + local_irq_restore(flags); cpu->last_sample_time = cpu->sample.time; |