Re: [PATCH V2 1/9] cpufreq: Auto-register with energy model if asked

From: Quentin Perret
Date: Wed Aug 11 2021 - 09:03:09 EST


On Wednesday 11 Aug 2021 at 17:28:39 (+0530), Viresh Kumar wrote:
> Many cpufreq drivers register with the energy model for each policy and
> do exactly the same thing. Follow the footsteps of thermal-cooling, to
> get it done from the cpufreq core itself.
>
> Provide a new callback, which will be called, if present, by the cpufreq
> core at the right moment (more on that in the code's comment). Also
> provide a generic implementation that uses dev_pm_opp_of_register_em().
>
> This also allows us to register with the EM at a later point of time,
> compared to ->init(), from where the EM core can access cpufreq policy
> directly using cpufreq_cpu_get() type of helpers and perform other work,
> like marking few frequencies inefficient, this will be done separately.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> ---
> drivers/cpufreq/cpufreq.c | 12 ++++++++++++
> include/linux/cpufreq.h | 14 ++++++++++++++
> 2 files changed, 26 insertions(+)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 06c526d66dd3..75974e7d6cc5 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1493,6 +1493,18 @@ static int cpufreq_online(unsigned int cpu)
> write_unlock_irqrestore(&cpufreq_driver_lock, flags);
> }
>
> + /*
> + * Register with the energy model before sched_cpufreq_governor_change()
> + * is called, which will result in rebuilding of the sched domains,
> + * which should only be done once the energy model is properly
> + * initialized for the policy first.
> + *
> + * Also, this should be called before the policy is registered with
> + * cooling framework.
> + */
> + if (cpufreq_driver->register_em)
> + cpufreq_driver->register_em(policy);

Maybe move that to the 'if (new_policy)' block above? There is currently
no need to re-register the EM on CPU hotplug.

> ret = cpufreq_init_policy(policy);
> if (ret) {
> pr_err("%s: Failed to initialize policy for cpu: %d (%d)\n",
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index 9fd719475fcd..1295621f6c28 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -9,10 +9,12 @@
> #define _LINUX_CPUFREQ_H
>
> #include <linux/clk.h>
> +#include <linux/cpu.h>
> #include <linux/cpumask.h>
> #include <linux/completion.h>
> #include <linux/kobject.h>
> #include <linux/notifier.h>
> +#include <linux/pm_opp.h>
> #include <linux/pm_qos.h>
> #include <linux/spinlock.h>
> #include <linux/sysfs.h>
> @@ -373,6 +375,12 @@ struct cpufreq_driver {
> /* platform specific boost support code */
> bool boost_enabled;
> int (*set_boost)(struct cpufreq_policy *policy, int state);
> +
> + /*
> + * Set by drivers that want the core to automatically register the
> + * policy's devices with Energy Model.
> + */
> + void (*register_em)(struct cpufreq_policy *policy);
> };
>
> /* flags */
> @@ -1046,4 +1054,10 @@ unsigned int cpufreq_generic_get(unsigned int cpu);
> void cpufreq_generic_init(struct cpufreq_policy *policy,
> struct cpufreq_frequency_table *table,
> unsigned int transition_latency);
> +
> +static inline void cpufreq_register_em_with_opp(struct cpufreq_policy *policy)
> +{
> + dev_pm_opp_of_register_em(get_cpu_device(policy->cpu),
> + policy->related_cpus);
> +}

I was thinking this could go in pm_opp.h instead, but it doesn't really
matter.

So, with the first comment above fixed:

Reviewed-by: Quentin Perret <qperret@xxxxxxxxxx>

Thanks,
Quentin