linux-kernel - [PATCH] cpufreq: Fix initialization of min and max frequency QoS requests

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Date:   Thu, 16 Dec 2021 20:32:15 +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>,
        Viresh Kumar <viresh.kumar@...aro.org>
Subject: [PATCH] cpufreq: Fix initialization of min and max frequency QoS requests

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

The min and max frequency QoS requests in the cpufreq core are
initialized to whatever the current min and max frequency values are
at the init time, but if any of these values change later (for
example, cpuinfo.max_freq is updated by the driver), these initial
request values will be limiting the CPU frequency unnecessarily
unless they are changed by user space via sysfs.

To address this, initialize min_freq_req and max_freq_req to
FREQ_QOS_MIN_DEFAULT_VALUE and FREQ_QOS_MAX_DEFAULT_VALUE,
respectively, so they don't really limit anything until user
space updates them.

Reported-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Tested-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/cpufreq/cpufreq.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux-pm/drivers/cpufreq/cpufreq.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/cpufreq.c
+++ linux-pm/drivers/cpufreq/cpufreq.c
@@ -1403,7 +1403,7 @@ static int cpufreq_online(unsigned int c
 
 		ret = freq_qos_add_request(&policy->constraints,
 					   policy->min_freq_req, FREQ_QOS_MIN,
-					   policy->min);
+					   FREQ_QOS_MIN_DEFAULT_VALUE);
 		if (ret < 0) {
 			/*
 			 * So we don't call freq_qos_remove_request() for an
@@ -1423,7 +1423,7 @@ static int cpufreq_online(unsigned int c
 
 		ret = freq_qos_add_request(&policy->constraints,
 					   policy->max_freq_req, FREQ_QOS_MAX,
-					   policy->max);
+					   FREQ_QOS_MAX_DEFAULT_VALUE);
 		if (ret < 0) {
 			policy->max_freq_req = NULL;
 			goto out_destroy_policy;