linux-kernel - [PATCH 4.20 07/57] cpufreq: scmi: Fix frequency invariance in slow path

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Date:   Tue, 15 Jan 2019 17:35:48 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Quentin Perret <quentin.perret@....com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Sudeep Holla <sudeep.holla@....com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH 4.20 07/57] cpufreq: scmi: Fix frequency invariance in slow path

4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Quentin Perret <quentin.perret@....com>

commit 0e141d1c65c1dd31c914eb2e11651adcc1a15912 upstream.

The scmi-cpufreq driver calls the arch_set_freq_scale() callback on
frequency changes to provide scale-invariant load-tracking signals to
the scheduler. However, in the slow path, it does so while specifying
the current and max frequencies in different units, hence resulting in a
broken freq_scale factor.

Fix this by passing all frequencies in KHz, as stored in the CPUFreq
frequency table.

Fixes: 99d6bdf33877 (cpufreq: add support for CPU DVFS based on SCMI message protocol)
Signed-off-by: Quentin Perret <quentin.perret@....com>
Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
Acked-by: Sudeep Holla <sudeep.holla@....com>
Cc: 4.17+ <stable@...r.kernel.org> # v4.17+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/cpufreq/scmi-cpufreq.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/cpufreq/scmi-cpufreq.c
+++ b/drivers/cpufreq/scmi-cpufreq.c
@@ -52,9 +52,9 @@ scmi_cpufreq_set_target(struct cpufreq_p
 	int ret;
 	struct scmi_data *priv = policy->driver_data;
 	struct scmi_perf_ops *perf_ops = handle->perf_ops;
-	u64 freq = policy->freq_table[index].frequency * 1000;
+	u64 freq = policy->freq_table[index].frequency;

-	ret = perf_ops->freq_set(handle, priv->domain_id, freq, false);
+	ret = perf_ops->freq_set(handle, priv->domain_id, freq * 1000, false);
 	if (!ret)
 		arch_set_freq_scale(policy->related_cpus, freq,
 				    policy->cpuinfo.max_freq);