From f55ae08c89873e140c7cac2a7fa161d31a0d60cf Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Wed, 4 May 2022 13:51:35 +0530 Subject: cpufreq: Avoid unnecessary frequency updates due to mismatch For some platforms, the frequency returned by hardware may be slightly different from what is provided in the frequency table. For example, hardware may return 499 MHz instead of 500 MHz. In such cases it is better to avoid getting into unnecessary frequency updates, as we may end up switching policy->cur between the two and sending unnecessary pre/post update notifications, etc. This patch has chosen allows the hardware frequency and table frequency to deviate by 1 MHz for now, we may want to increase it a bit later on if someone still complains. Reported-by: Rex-BC Chen Signed-off-by: Viresh Kumar Tested-by: Jia-wei Chang Reviewed-by: Matthias Brugger Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/cpufreq.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'drivers/cpufreq/cpufreq.c') diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 0d58b0f8f3af..233e8af48848 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -28,6 +28,7 @@ #include #include #include +#include #include static LIST_HEAD(cpufreq_policy_list); @@ -1708,6 +1709,16 @@ static unsigned int cpufreq_verify_current_freq(struct cpufreq_policy *policy, b return new_freq; if (policy->cur != new_freq) { + /* + * For some platforms, the frequency returned by hardware may be + * slightly different from what is provided in the frequency + * table, for example hardware may return 499 MHz instead of 500 + * MHz. In such cases it is better to avoid getting into + * unnecessary frequency updates. + */ + if (abs(policy->cur - new_freq) < HZ_PER_MHZ) + return policy->cur; + cpufreq_out_of_sync(policy, new_freq); if (update) schedule_work(&policy->update); -- cgit v1.2.3