From d4436c0dba8d4d780588179a2e192a867d266a10 Mon Sep 17 00:00:00 2001 From: Srinivas Pandruvada Date: Mon, 10 Jul 2017 16:23:52 -0700 Subject: [PATCH] cpufreq: intel_pstate: Fix ratio setting for min_perf_pct When the minimum performance limit percentage is set to the power-up default, it is possible that minimum performance ratio is off by one. In the set_policy() callback the minimum ratio is calculated by applying global.min_perf_pct to turbo_ratio and rounding up, but the power-up default global.min_perf_pct is already rounded up to the next percent in min_perf_pct_min(). That results in two round up operations, so for the default min_perf_pct one of them is not required. It is better to remove rounding up in min_perf_pct_min() as this matches the displayed min_perf_pct prior to commit c5a2ee7dde89 (cpufreq: intel_pstate: Active mode P-state limits rework) in 4.12. For example on a platform with max turbo ratio of 37 and minimum ratio of 10, the min_perf_pct resulted in 28 with the above commit. Before this commit it was 27 and it will be the same after this change. Fixes: 1a4fe38add8b (cpufreq: intel_pstate: Remove max/min fractions to limit performance) Reported-by: Artem Bityutskiy Signed-off-by: Srinivas Pandruvada Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/intel_pstate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index 756483251832..2386d7036e90 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -572,7 +572,7 @@ static int min_perf_pct_min(void) int turbo_pstate = cpu->pstate.turbo_pstate; return turbo_pstate ? - DIV_ROUND_UP(cpu->pstate.min_pstate * 100, turbo_pstate) : 0; + (cpu->pstate.min_pstate * 100 / turbo_pstate) : 0; } static s16 intel_pstate_get_epb(struct cpudata *cpu_data) -- 2.20.1