On Mon, Aug 3, 2020 at 3:26 PM Ionela Voinescu [off-list ref] wrote:

Hi guys,

On Thursday 30 Jul 2020 at 09:11:28 (+0530), Viresh Kumar wrote:

quoted

On 27-07-20, 15:48, Rafael J. Wysocki wrote:

quoted

On Wed, Jul 22, 2020 at 11:38 AM Ionela Voinescu
[off-list ref] wrote:

quoted

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 036f4cc42ede..bac4101546db 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c

@@ -2058,9 +2058,16 @@ EXPORT_SYMBOL(cpufreq_unregister_notifier);
 unsigned int cpufreq_driver_fast_switch(struct cpufreq_policy *policy,
                                        unsigned int target_freq)
 {
+       unsigned int freq;
+
        target_freq = clamp_val(target_freq, policy->min, policy->max);
+       freq = cpufreq_driver->fast_switch(policy, target_freq);
+
+       if (freq)
+               arch_set_freq_scale(policy->related_cpus, freq,
+                                   policy->cpuinfo.max_freq);

Why can't arch_set_freq_scale() handle freq == 0?

Sorry, I seem to have missed this question the first time around.

arch_set_freq_scale() could handle freq == 0, but given that freq == 0
is signaling an error here, I do believe this check is well placed, to
prevent a useless call to arch_set_freq_scale(). Also [1]:

So let me rephrase:

Doesn't this check add overhead in the empty arch_set_freq_scale() case?