cpufreq: intel_pstate: round up min_perf limits

In some use cases, user wants to enforce a minimum performance limit on
CPUs. But because of simple division the resultant performance is 100 MHz
less than the desired in some cases.

For example when the maximum frequency is 3.50 GHz, setting
scaling_min_frequency to 1.6 GHz always results in 1.5 GHz minimum. With
simple round up, the frequency can be set to 1.6 GHz to minimum in this
case. This round up is already done to max_policy_pct and max_perf, so do
the same for min_policy_pct and min_perf.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 0d82bf320838c5188fd67d99b97bb462f9f721a1..e5ef51d7be4ea7338ccbb3d111cc1b7fc7559740 100644 (file)
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -1583,8 +1583,8 @@ static void intel_pstate_update_perf_limits(struct cpufreq_policy *policy,
        if (policy->max == policy->min) {
                limits->min_policy_pct = limits->max_policy_pct;
        } else {
-               limits->min_policy_pct = (policy->min * 100) /
-                                               policy->cpuinfo.max_freq;
+               limits->min_policy_pct = DIV_ROUND_UP(policy->min * 100,
+                                                     policy->cpuinfo.max_freq);
                limits->min_policy_pct = clamp_t(int, limits->min_policy_pct,
                                                 0, 100);
        }
@@ -1605,6 +1605,7 @@ static void intel_pstate_update_perf_limits(struct cpufreq_policy *policy,
        limits->min_perf = div_fp(limits->min_perf_pct, 100);
        limits->max_perf = div_fp(limits->max_perf_pct, 100);
        limits->max_perf = round_up(limits->max_perf, FRAC_BITS);
+       limits->min_perf = round_up(limits->min_perf, FRAC_BITS);
 
        mutex_unlock(&intel_pstate_limits_lock);