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| author | Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> | 2017-07-11 01:23:52 +0200 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2017-07-12 14:39:10 +0200 |
| commit | d4436c0dba8d4d780588179a2e192a867d266a10 (patch) | |
| tree | f2f996abdbf89665ee83d86ad66b1455c5910b4a /drivers/cpufreq | |
| parent | cpufreq: Update scaling_cur_freq documentation (diff) | |
| download | linux-d4436c0dba8d4d780588179a2e192a867d266a10.tar.xz linux-d4436c0dba8d4d780588179a2e192a867d266a10.zip | |
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 <artem.bityutskiy@linux.intel.com>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq')
| -rw-r--r-- | drivers/cpufreq/intel_pstate.c | 2 |
1 files changed, 1 insertions, 1 deletions
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) |