linux-kernel - [PATCH v4 4/4] cpufreq: Use arch specific feedback for cpuinfo_cur

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Message-Id: <20240405133319.859813-5-beata.michalska@arm.com>
Date: Fri,  5 Apr 2024 14:33:19 +0100
From: Beata Michalska <beata.michalska@....com>
To: linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	ionela.voinescu@....com,
	vanshikonda@...amperecomputing.com
Cc: sudeep.holla@....com,
	will@...nel.org,
	catalin.marinas@....com,
	vincent.guittot@...aro.org,
	sumitg@...dia.com,
	yang@...amperecomputing.com,
	lihuisong@...wei.com
Subject: [PATCH v4 4/4] cpufreq: Use arch specific feedback for cpuinfo_cur_freq

Some architectures provide a way to determine an average frequency over
a certain period of time based on available performance monitors (AMU on
ARM or APERF/MPERf on x86). With those at hand, enroll arch_freq_get_on_cpu
into cpuinfo_cur_freq policy sysfs attribute handler, which is expected to
represent the current frequency of a given CPU, as obtained by the hardware.
This is the type of feedback that counters do provide.

Signed-off-by: Beata Michalska <beata.michalska@....com>
---
 drivers/cpufreq/cpufreq.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 66e10a19d76a..603533b2608f 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -795,8 +795,10 @@ store_one(scaling_max_freq, max);
 static ssize_t show_cpuinfo_cur_freq(struct cpufreq_policy *policy,
 					char *buf)
 {
-	unsigned int cur_freq = __cpufreq_get(policy);
+	unsigned int cur_freq = arch_freq_get_on_cpu(policy->cpu);
 
+	if (!cur_freq)
+		cur_freq = __cpufreq_get(policy);
 	if (cur_freq)
 		return sprintf(buf, "%u\n", cur_freq);
 
-- 
2.25.1