Re: [PATCH v4 20/20] cpufreq: scmi: add support for fast frequency switching

[Viresh Kumar <viresh.kumar@linaro.org>]

On 03-11-17, 14:47, Sudeep Holla wrote:
> The cpufreq core provides option for drivers to implement fast_switch
> callback which is invoked for frequency switching from interrupt context.
> 
> This patch adds support for fast_switch callback in SCMI cpufreq driver
> by making use of polling based SCMI transfer. It also sets the flag
> fast_switch_possible.
> 
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> Cc: Viresh Kumar <viresh.kumar@linaro.org>
> Cc: linux-pm@vger.kernel.org
> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
> ---
>  drivers/cpufreq/scmi-cpufreq.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
> index b1057a13e6a7..91df5013f7b2 100644
> --- a/drivers/cpufreq/scmi-cpufreq.c
> +++ b/drivers/cpufreq/scmi-cpufreq.c
> @@ -64,6 +64,19 @@ scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
>  	return perf_ops->freq_set(handle, priv->domain_id, freq, false);
>  }
>  
> +static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy,
> +					     unsigned int target_freq)
> +{
> +	struct scmi_data *priv = policy->driver_data;
> +	struct scmi_perf_ops *perf_ops = handle->perf_ops;
> +
> +	if (!perf_ops->freq_set(handle, priv->domain_id,
> +				target_freq * 1000, true))
> +		return target_freq;
> +
> +	return 0;
> +}
> +
>  static int
>  scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
>  {
> @@ -167,6 +180,7 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>  
>  	policy->cpuinfo.transition_latency = latency;
>  
> +	policy->fast_switch_possible = true;
>  	return 0;
>  
>  out_free_cpufreq_table:
> @@ -183,6 +197,7 @@ static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
>  {
>  	struct scmi_data *priv = policy->driver_data;
>  
> +	policy->fast_switch_possible = false;

You don't need this.

>  	cpufreq_cooling_unregister(priv->cdev);
>  	dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
>  	kfree(priv);
> @@ -226,6 +241,7 @@ static struct cpufreq_driver scmi_cpufreq_driver = {
>  	.verify	= cpufreq_generic_frequency_table_verify,
>  	.attr	= cpufreq_generic_attr,
>  	.target_index	= scmi_cpufreq_set_target,
> +	.fast_switch	= scmi_cpufreq_fast_switch,
>  	.get	= scmi_cpufreq_get_rate,
>  	.init	= scmi_cpufreq_init,
>  	.exit	= scmi_cpufreq_exit,

Apart from that.

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

-- 
viresh