linux-kernel - [PATCH] cpufreq: apple-soc: Switch to the lowest frequency on suspend

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Date:   Wed,  4 Jan 2023 19:21:49 +0900
From:   Hector Martin <marcan@...can.st>
To:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Hector Martin <marcan@...can.st>, Sven Peter <sven@...npeter.dev>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Marc Zyngier <maz@...nel.org>, asahi@...ts.linux.dev,
        linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] cpufreq: apple-soc: Switch to the lowest frequency on suspend

Without this, the CPUs are left in a random pstate. Since we don't
support deep idle yet (which powers down the CPUs), this results in
significantly increased idle power consumption in suspend.

Fixes: 6286bbb40576 ("cpufreq: apple-soc: Add new driver to control Apple SoC CPU P-states")
Signed-off-by: Hector Martin <marcan@...can.st>
---
 drivers/cpufreq/apple-soc-cpufreq.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/cpufreq/apple-soc-cpufreq.c b/drivers/cpufreq/apple-soc-cpufreq.c
index d1801281cdd9..1b4e6c701860 100644
--- a/drivers/cpufreq/apple-soc-cpufreq.c
+++ b/drivers/cpufreq/apple-soc-cpufreq.c
@@ -280,6 +280,7 @@ static int apple_soc_cpufreq_init(struct cpufreq_policy *policy)
 	policy->cpuinfo.transition_latency = transition_latency;
 	policy->dvfs_possible_from_any_cpu = true;
 	policy->fast_switch_possible = true;
+	policy->suspend_freq = freq_table[0].frequency;
 
 	if (policy_has_boost_freq(policy)) {
 		ret = cpufreq_enable_boost_support();
@@ -329,6 +330,7 @@ static struct cpufreq_driver apple_soc_cpufreq_driver = {
 	.fast_switch	= apple_soc_cpufreq_fast_switch,
 	.register_em	= cpufreq_register_em_with_opp,
 	.attr		= apple_soc_cpufreq_hw_attr,
+	.suspend	= cpufreq_generic_suspend,
 };
 
 static int __init apple_soc_cpufreq_module_init(void)
-- 
2.35.1