linux-kernel - [PATCH] cpufreq: freq_table: Initialize cpuinfo.max

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Date:   Mon, 15 Nov 2021 14:50:11 -0500
From:   Thara Gopinath <thara.gopinath@...aro.org>
To:     rafael@...nel.org, viresh.kumar@...aro.org,
        bjorn.andersson@...aro.org
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org
Subject: [PATCH] cpufreq: freq_table: Initialize cpuinfo.max_freq to correct max frequency.

cpuinfo.max_freq reflects the maximum supported frequency of cpus in a
cpufreq policy. When cpus support boost frequency and if boost is disabled
during boot up (which is the default), cpuinfo.max_freq does not reflect
boost frequency as the maximum supported frequency till boost is explicitly
enabled via sysfs interface later. This also means that policy reports two
different cpuinfo.max_freq before and after turning on boost.  Fix this by
separating out setting of policy->max and cpuinfo.max_freq in
cpufreq_frequency_table_cpuinfo.

e.g. of the problem. Qualcomm sdm845 supports boost frequency for gold
cluster (cpus 4-7). After boot up (boost disabled),

1.  cat /sys/devices/system/cpu/cpufreq/policy4/cpuinfo_max_freq 2649600
<- This is wrong because boost frequency is

2.  echo 1 > /sys/devices/system/cpu/cpufreq/boost  <- Enable boost cat
/sys/devices/system/cpu/cpufreq/policy4/cpuinfo_max_freq 2803200	<-
max freq reflects boost freq.

3.  echo 0 > /sys/devices/system/cpu/cpufreq/boost <- Disable boost cat
/sys/devices/system/cpu/cpufreq/policy4/cpuinfo_max_freq 2803200	<-
Discrepancy with step 1 as in both cases boost is disabled.

Note that the other way to fix this is to set cpuinfo.max_freq in Soc
cpufreq driver during initialization. Fixing it in
cpufreq_frequency_table_cpuinfo seems more generic solution

Signed-off-by: Thara Gopinath <thara.gopinath@...aro.org>
---
 drivers/cpufreq/freq_table.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/freq_table.c b/drivers/cpufreq/freq_table.c
index 67e56cf638ef..6784f94124df 100644
--- a/drivers/cpufreq/freq_table.c
+++ b/drivers/cpufreq/freq_table.c
@@ -35,11 +35,15 @@ int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy,
 	struct cpufreq_frequency_table *pos;
 	unsigned int min_freq = ~0;
 	unsigned int max_freq = 0;
+	unsigned int cpuinfo_max_freq = 0;
 	unsigned int freq;

 	cpufreq_for_each_valid_entry(pos, table) {
 		freq = pos->frequency;

+		if (freq > cpuinfo_max_freq)
+			cpuinfo_max_freq = freq;
+
 		if (!cpufreq_boost_enabled()
 		    && (pos->flags & CPUFREQ_BOOST_FREQ))
 			continue;
@@ -57,8 +61,8 @@ int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy,
 	 * If the driver has set its own cpuinfo.max_freq above max_freq, leave
 	 * it as is.
 	 */
-	if (policy->cpuinfo.max_freq < max_freq)
-		policy->max = policy->cpuinfo.max_freq = max_freq;
+	if (policy->cpuinfo.max_freq < cpuinfo_max_freq)
+		policy->cpuinfo.max_freq = cpuinfo_max_freq;

 	if (policy->min == ~0)
 		return -EINVAL;
-- 
2.25.1