@@ -845,7 +845,7 @@ static struct freq_attr *hwp_cpufreq_attrs[] = {
static void intel_pstate_hwp_set(struct cpufreq_policy *policy)
{
- int min, hw_min, max, hw_max, cpu, range, adj_range;
+ int min, hw_min, max, hw_max, cpu;
struct perf_limits *perf_limits = limits;
u64 value, cap;
@@ -863,20 +863,17 @@ static void intel_pstate_hwp_set(struct cpufreq_policy *policy)
hw_max = HWP_GUARANTEED_PERF(cap);
else
hw_max = HWP_HIGHEST_PERF(cap);
- range = hw_max - hw_min;
max_perf_pct = perf_limits->max_perf_pct;
min_perf_pct = perf_limits->min_perf_pct;
+ min = hw_max * min_perf_pct / 100;
rdmsrl_on_cpu(cpu, MSR_HWP_REQUEST, &value);
- adj_range = min_perf_pct * range / 100;
- min = hw_min + adj_range;
+
value &= ~HWP_MIN_PERF(~0L);
value |= HWP_MIN_PERF(min);
- adj_range = max_perf_pct * range / 100;
- max = hw_min + adj_range;
-
+ max = hw_max * max_perf_pct / 100;
value &= ~HWP_MAX_PERF(~0L);
value |= HWP_MAX_PERF(max);
In the functions intel_pstate_hwp_set(), min/max range from HWP capability MSR along with max_perf_pct and min_perf_pct, is used to set the HWP request MSR. In some cases this doesn't result in the correct HWP max/min in HWP request. For example: In the following case: HWP capabilities from MSR 0x771 0x70a1220 Here cpufreq min/max frequencies from above MSR dump are 700MHz and 3.2GHz respectively. This will result in hwp_min = 0x07 hwp_max = 0x20 To limit max frequency to 2GHz: perf_limits->max_perf_pct = 63 (2GHz as a percent of 3.2GHz rounded up) With the current calculation: adj_range = max_perf_pct * range / 100; adj_range = 63 * (32 - 7) / 100 adj_range = 15 max = hw_min + adj_range; max = 7 + 15 = 22 This will result in HWP request of 0x160f, which will result in a frequency cap of 2.2GHz not 2GHz. The problem with the above calculation is that hwp_min of 7 is treated as 0% in the range. But max_perf_pct is calculated with respect to minimum as 0 and max as 3.2GHz or hwp_max, so adding hwp_min to it will result in more than the desired. Since the min_perf_pct and max_perf_pct is already a percent of max frequency or hwp_max, this min/max HWP request value can be calculated directly applying these percentage to hwp_max. Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> --- drivers/cpufreq/intel_pstate.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-)