On Wed, Nov 26, 2014 at 11:22:58AM +0530, Viresh Kumar wrote:
> Currently there is no callback for cpufreq drivers which is called once the
> policy is ready to be used. There are some requirements where such a callback is
> required.
> 
> One of them is registering a cooling device with the help of
> of_cpufreq_cooling_register(). This routine tries to get 'struct cpufreq_policy'
> for CPUs which isn't yet initialed at the time ->init() is called and so we face
> issues while registering the cooling device.
> 
> Because we can't register cooling device from ->init(), we need a callback that
> is called after the policy is ready to be used and hence we introduce ->usable()
> callback.
> 

Reviewed-by: Eduardo Valentin <edubezval@gmail.com>
Tested-by: Eduardo Valentin <edubezval@gmail.com>

> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
>  drivers/cpufreq/cpufreq.c | 5 +++++
>  include/linux/cpufreq.h   | 4 ++++
>  2 files changed, 9 insertions(+)
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index de2c3e1..4fb95b9 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1285,8 +1285,13 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
>  	up_write(&policy->rwsem);
>  
>  	kobject_uevent(&policy->kobj, KOBJ_ADD);
> +
>  	up_read(&cpufreq_rwsem);
>  
> +	/* Callback for handling stuff after policy is ready */
> +	if (cpufreq_driver->usable)
> +		cpufreq_driver->usable(policy);
> +
>  	pr_debug("initialization complete\n");
>  
>  	return 0;
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index db3c130..4795c0b 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -267,6 +267,10 @@ struct cpufreq_driver {
>  	void		(*stop_cpu)(struct cpufreq_policy *policy);
>  	int		(*suspend)(struct cpufreq_policy *policy);
>  	int		(*resume)(struct cpufreq_policy *policy);
> +
> +	/* Will be called after the driver is fully initialized */
> +	void		(*usable)(struct cpufreq_policy *policy);
> +
>  	struct freq_attr **attr;
>  
>  	/* platform specific boost support code */
> -- 
> 2.0.3.693.g996b0fd
>