linux-kernel - [PATCH v1 3/6] cpufreq: intel_pstate: Rearrange show_no_turbo() and store_no

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Message-ID: <2276522.iZASKD2KPV@kreacher>
Date: Mon, 25 Mar 2024 18:03:25 +0100
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
 Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Subject:
 [PATCH v1 3/6] cpufreq: intel_pstate: Rearrange show_no_turbo() and
 store_no_turbo()

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

Now that global.turbo_disabled can only change at the cpufreq driver
registration time, initialize global.no_turbo at that time too so they
are in sync to start with (if the former is set, the latter cannot be
updated later anyway).

That allows show_no_turbo() to be simlified because it does not need
to check global.turbo_disabled and store_no_turbo() can be rearranged
to avoid doing anything if the new value of global.no_turbo is equal
to the current one and only return an error on attempts to clear
global.no_turbo when global.turbo_disabled.

While at it, eliminate the redundant ret variable from store_no_turbo().

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/cpufreq/intel_pstate.c |   34 ++++++++++++++++++----------------
 1 file changed, 18 insertions(+), 16 deletions(-)

Index: linux-pm/drivers/cpufreq/intel_pstate.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/intel_pstate.c
+++ linux-pm/drivers/cpufreq/intel_pstate.c
@@ -1262,10 +1262,7 @@ static ssize_t show_no_turbo(struct kobj
 		return -EAGAIN;
 	}

-	if (global.turbo_disabled)
-		ret = sprintf(buf, "%u\n", global.turbo_disabled);
-	else
-		ret = sprintf(buf, "%u\n", global.no_turbo);
+	ret = sprintf(buf, "%u\n", global.no_turbo);

 	mutex_unlock(&intel_pstate_driver_lock);

@@ -1276,31 +1273,34 @@ static ssize_t store_no_turbo(struct kob
 			      const char *buf, size_t count)
 {
 	unsigned int input;
-	int ret;
+	bool no_turbo;

-	ret = sscanf(buf, "%u", &input);
-	if (ret != 1)
+	if (sscanf(buf, "%u", &input) != 1)
 		return -EINVAL;

 	mutex_lock(&intel_pstate_driver_lock);

 	if (!intel_pstate_driver) {
-		mutex_unlock(&intel_pstate_driver_lock);
-		return -EAGAIN;
+		count = -EAGAIN;
+		goto unlock_driver;
 	}

-	mutex_lock(&intel_pstate_limits_lock);
+	no_turbo = !!clamp_t(int, input, 0, 1);
+
+	if (no_turbo == global.no_turbo)
+		goto unlock_driver;

 	if (global.turbo_disabled) {
 		pr_notice_once("Turbo disabled by BIOS or unavailable on processor\n");
-		mutex_unlock(&intel_pstate_limits_lock);
-		mutex_unlock(&intel_pstate_driver_lock);
-		return -EPERM;
+		count = -EPERM;
+		goto unlock_driver;
 	}

-	global.no_turbo = clamp_t(int, input, 0, 1);
+	global.no_turbo = no_turbo;
+
+	mutex_lock(&intel_pstate_limits_lock);

-	if (global.no_turbo) {
+	if (no_turbo) {
 		struct cpudata *cpu = all_cpu_data[0];
 		int pct = cpu->pstate.max_pstate * 100 / cpu->pstate.turbo_pstate;

@@ -1312,8 +1312,9 @@ static ssize_t store_no_turbo(struct kob
 	mutex_unlock(&intel_pstate_limits_lock);

 	intel_pstate_update_policies();
-	arch_set_max_freq_ratio(global.no_turbo);
+	arch_set_max_freq_ratio(no_turbo);

+unlock_driver:
 	mutex_unlock(&intel_pstate_driver_lock);

 	return count;
@@ -3094,6 +3095,7 @@ static int intel_pstate_register_driver(
 	memset(&global, 0, sizeof(global));
 	global.max_perf_pct = 100;
 	global.turbo_disabled = turbo_is_disabled();
+	global.no_turbo = global.turbo_disabled;

 	arch_set_max_freq_ratio(global.turbo_disabled);