linux-kernel - [PATCH v1 3/3] cpufreq: intel_pstate: Adjust frequency percentage computations

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Message-ID: <3395556.44csPzL39Z@rafael.j.wysocki>
Date: Fri, 05 Sep 2025 15:53:54 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
 LKML <linux-kernel@...r.kernel.org>, Viresh Kumar <viresh.kumar@...aro.org>,
 Zihuan Zhang <zhangzihuan@...inos.cn>,
 Jonathan Cameron <jonathan.cameron@...wei.com>
Subject:
 [PATCH v1 3/3] cpufreq: intel_pstate: Adjust frequency percentage
 computations

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Adjust frequency percentage computations in update_cpu_qos_request() to
avoid going above the exact numerical percentage in the FREQ_QOS_MAX
case.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/cpufreq/intel_pstate.c |    8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -1696,8 +1696,8 @@ unlock_driver:
 static void update_cpu_qos_request(int cpunum, enum freq_qos_req_type type)
 {
 	struct cpudata *cpu = all_cpu_data[cpunum];
+	unsigned int freq = cpu->pstate.turbo_freq;
 	struct freq_qos_request *req;
-	unsigned int freq, perf_pct;

 	struct cpufreq_policy *policy __free(put_cpufreq_policy) = cpufreq_cpu_get(cpunum);
 	if (!policy)
@@ -1711,14 +1711,12 @@ static void update_cpu_qos_request(int c
 		intel_pstate_get_hwp_cap(cpu);

 	if (type == FREQ_QOS_MIN) {
-		perf_pct = global.min_perf_pct;
+		freq = DIV_ROUND_UP(freq * global.min_perf_pct, 100);
 	} else {
 		req++;
-		perf_pct = global.max_perf_pct;
+		freq = (freq * global.max_perf_pct) / 100;
 	}

-	freq = DIV_ROUND_UP(cpu->pstate.turbo_freq * perf_pct, 100);
-
 	if (freq_qos_update_request(req, freq) < 0)
 		pr_warn("Failed to update freq constraint: CPU%d\n", cpunum);
 }