Re: [PATCH] cpufreq: Abort cpufreq_update_current_freq() for cpufreq_suspended set

[Viresh Kumar]

On 10 April 2016 at 09:38, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> Since governor operations are generally skipped if cpufreq_suspended
> is set, cpufreq_start_governor() should do nothing in that case.
>
> That function is called in the cpufreq_online() path, and may also
> be called from cpufreq_offline() in some cases, which are invoked
> by the nonboot CPUs disabing/enabling code during system suspend
> to RAM and resume.  That happens when all devices have been
> suspended, so if the cpufreq driver relies on things like I2C to
> get the current frequency, it may not be ready to do that then.
>
> To prevent problems from happening for this reason, make
> cpufreq_update_current_freq(), which is the only function invoked
> by cpufreq_start_governor() that doesn't check cpufreq_suspended
> already, return 0 upfront if cpufreq_suspended is set.
>
> Fixes: 3bbf8fe3ae08 (cpufreq: Always update current frequency before startig governor)
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
>  drivers/cpufreq/cpufreq.c |    3 +++
>  1 file changed, 3 insertions(+)
>
> Index: linux-pm/drivers/cpufreq/cpufreq.c
> ===================================================================
> --- linux-pm.orig/drivers/cpufreq/cpufreq.c
> +++ linux-pm/drivers/cpufreq/cpufreq.c
> @@ -1565,6 +1565,9 @@ static unsigned int cpufreq_update_curre
>  {
>         unsigned int new_freq;
>
> +       if (cpufreq_suspended)
> +               return 0;
> +
>         new_freq = cpufreq_driver->get(policy->cpu);
>         if (!new_freq)
>                 return 0;

Acked-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>