On Wed, Nov 26, 2014 at 11:22:59AM +0530, Viresh Kumar wrote:
> Currently we are calling of_cpufreq_cooling_register() from ->init() callback.
> At this point of time cpufreq driver's policy isn't completely ready to be used
> as few of its fields/structure/pointers aren't yet initialized.
> 
> Because of_cpufreq_cooling_register() tries to access policy with help of
> cpufreq_cpu_get() and then tries to get freq-table as well, these calls fail.
> 
> To fix this, register the cooling device after the policy is ready to be used.
> And the right callback for it is the newly added ->usable() one.
> 
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

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

> ---
>  drivers/cpufreq/cpufreq-dt.c | 51 +++++++++++++++++++++++++++-----------------
>  1 file changed, 32 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c
> index 7374fc4..f7af5c8 100644
> --- a/drivers/cpufreq/cpufreq-dt.c
> +++ b/drivers/cpufreq/cpufreq-dt.c
> @@ -186,7 +186,6 @@ static int cpufreq_init(struct cpufreq_policy *policy)
>  {
>  	struct cpufreq_dt_platform_data *pd;
>  	struct cpufreq_frequency_table *freq_table;
> -	struct thermal_cooling_device *cdev;
>  	struct device_node *np;
>  	struct private_data *priv;
>  	struct device *cpu_dev;
> @@ -269,20 +268,6 @@ static int cpufreq_init(struct cpufreq_policy *policy)
>  		goto out_free_priv;
>  	}
>  
> -	/*
> -	 * For now, just loading the cooling device;
> -	 * thermal DT code takes care of matching them.
> -	 */
> -	if (of_find_property(np, "#cooling-cells", NULL)) {
> -		cdev = of_cpufreq_cooling_register(np, policy->related_cpus);
> -		if (IS_ERR(cdev))
> -			dev_err(cpu_dev,
> -				"running cpufreq without cooling device: %ld\n",
> -				PTR_ERR(cdev));
> -		else
> -			priv->cdev = cdev;
> -	}
> -
>  	priv->cpu_dev = cpu_dev;
>  	priv->cpu_reg = cpu_reg;
>  	policy->driver_data = priv;
> @@ -292,7 +277,7 @@ static int cpufreq_init(struct cpufreq_policy *policy)
>  	if (ret) {
>  		dev_err(cpu_dev, "%s: invalid frequency table: %d\n", __func__,
>  			ret);
> -		goto out_cooling_unregister;
> +		goto out_free_cpufreq_table;
>  	}
>  
>  	policy->cpuinfo.transition_latency = transition_latency;
> @@ -305,8 +290,7 @@ static int cpufreq_init(struct cpufreq_policy *policy)
>  
>  	return 0;
>  
> -out_cooling_unregister:
> -	cpufreq_cooling_unregister(priv->cdev);
> +out_free_cpufreq_table:
>  	dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
>  out_free_priv:
>  	kfree(priv);
> @@ -324,7 +308,8 @@ static int cpufreq_exit(struct cpufreq_policy *policy)
>  {
>  	struct private_data *priv = policy->driver_data;
>  
> -	cpufreq_cooling_unregister(priv->cdev);
> +	if (priv->cdev)
> +		cpufreq_cooling_unregister(priv->cdev);
>  	dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
>  	clk_put(policy->clk);
>  	if (!IS_ERR(priv->cpu_reg))
> @@ -334,6 +319,33 @@ static int cpufreq_exit(struct cpufreq_policy *policy)
>  	return 0;
>  }
>  
> +static void cpufreq_usable(struct cpufreq_policy *policy)
> +{
> +	struct private_data *priv = policy->driver_data;
> +	struct device_node *np = of_node_get(priv->cpu_dev->of_node);
> +
> +	if (WARN_ON(!np))
> +		return;
> +
> +	/*
> +	 * For now, just loading the cooling device;
> +	 * thermal DT code takes care of matching them.
> +	 */
> +	if (of_find_property(np, "#cooling-cells", NULL)) {
> +		priv->cdev = of_cpufreq_cooling_register(np,
> +							 policy->related_cpus);
> +		if (IS_ERR(priv->cdev)) {
> +			dev_err(priv->cpu_dev,
> +				"running cpufreq without cooling device: %ld\n",
> +				PTR_ERR(priv->cdev));
> +
> +			priv->cdev = NULL;
> +		}
> +	}
> +
> +	of_node_put(np);
> +}
> +
>  static struct cpufreq_driver dt_cpufreq_driver = {
>  	.flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
>  	.verify = cpufreq_generic_frequency_table_verify,
> @@ -341,6 +353,7 @@ static struct cpufreq_driver dt_cpufreq_driver = {
>  	.get = cpufreq_generic_get,
>  	.init = cpufreq_init,
>  	.exit = cpufreq_exit,
> +	.usable = cpufreq_usable,
>  	.name = "cpufreq-dt",
>  	.attr = cpufreq_generic_attr,
>  };
> -- 
> 2.0.3.693.g996b0fd
>