Re: [PATCH v3 3/4] thermal/drivers/cpuidle_cooling: Change the registration function

[Daniel Lezcano <daniel.lezcano@linaro.org>]

Hi Lukasz,

On 28/04/2020 17:20, Lukasz Luba wrote:
> Hi Daniel,
> 
> I have checked the patches and run them on Juno.
> Please find my comments below.

thanks a lot for the review and the testing.



> On 4/14/20 11:08 PM, Daniel Lezcano wrote:
>> Today, there is no user for the cpuidle cooling device. The targetted
>> platform is ARM and ARM64.
>>
>> The cpuidle and the cpufreq cooling device are based on the device tree.
>>
>> As the cpuidle cooling device can have its own configuration depending
>> on the platform and the available idle states. The DT node description
>> will give the optional properties to set the cooling device up.
>>
>> Do no longer rely on the CPU node which is prone to error and will
>> lead to a confusion in the DT because the cpufreq cooling device is
>> also using it. Let initialize the cpuidle cooling device with the DT
>> binding.
>>
>> This was tested on:
>>   - hikey960
>>   - hikey6220
>>   - rock960
>>   - db845c
>>
>> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
>> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
>> ---
>>   drivers/thermal/cpuidle_cooling.c | 58 +++++++++++++++++++++++++------
>>   include/linux/cpu_cooling.h       |  7 ----
>>   2 files changed, 47 insertions(+), 18 deletions(-)
>>
>> diff --git a/drivers/thermal/cpuidle_cooling.c
>> b/drivers/thermal/cpuidle_cooling.c
>> index 0bb843246f59..b2c81c427f05 100644
>> --- a/drivers/thermal/cpuidle_cooling.c
>> +++ b/drivers/thermal/cpuidle_cooling.c
>> @@ -10,6 +10,7 @@
>>   #include <linux/err.h>
>>   #include <linux/idle_inject.h>
>>   #include <linux/idr.h>
>> +#include <linux/of_device.h>
>>   #include <linux/slab.h>
>>   #include <linux/thermal.h>
>>   @@ -154,22 +155,25 @@ static struct thermal_cooling_device_ops
>> cpuidle_cooling_ops = {
>>   };
>>     /**
>> - * cpuidle_of_cooling_register - Idle cooling device initialization
>> function
>> + * __cpuidle_cooling_register: register the cooling device
>>    * @drv: a cpuidle driver structure pointer
>> - * @np: a node pointer to a device tree cooling device node
>> + * @np: a device node structure pointer used for the thermal binding
>>    *
>> - * This function is in charge of creating a cooling device per cpuidle
>> - * driver and register it to thermal framework.
>> + * This function is in charge of allocating the cpuidle cooling device
>> + * structure, the idle injection, initialize them and register the
>> + * cooling device to the thermal framework.
>>    *
>> - * Return: zero on success, or negative value corresponding to the
>> - * error detected in the underlying subsystems.
>> + * Return: zero on success, a negative value returned by one of the
>> + * underlying subsystem in case of error
>>    */
>> -int cpuidle_of_cooling_register(struct device_node *np,
>> -                struct cpuidle_driver *drv)
>> +static int __cpuidle_cooling_register(struct device_node *np,
>> +                      struct cpuidle_driver *drv)
>>   {
>>       struct idle_inject_device *ii_dev;
>>       struct cpuidle_cooling_device *idle_cdev;
>>       struct thermal_cooling_device *cdev;
>> +    unsigned int idle_duration_us = TICK_USEC;
>> +    unsigned int latency_us = UINT_MAX;
>>       char dev_name[THERMAL_NAME_LENGTH];
>>       int id, ret;
>>   @@ -191,7 +195,11 @@ int cpuidle_of_cooling_register(struct
>> device_node *np,
>>           goto out_id;
>>       }
>>   -    idle_inject_set_duration(ii_dev, TICK_USEC, TICK_USEC);
>> +    of_property_read_u32(np, "duration", &idle_duration_us);
> 
> This probably is 'duration-us' according to DT bindings.
> 
>> +    of_property_read_u32(np, "latency", &latency_us);
> 
> the same here s/latency/exit-latency-us/
> 
>> +
>> +    idle_inject_set_duration(ii_dev, TICK_USEC, idle_duration_us);
>> +    idle_inject_set_latency(ii_dev, latency_us);
>>         idle_cdev->ii_dev = ii_dev;
>>   @@ -204,6 +212,9 @@ int cpuidle_of_cooling_register(struct
>> device_node *np,
>>           goto out_unregister;
>>       }
>>   +    pr_info("%s: Idle injection set with idle duration=%u,
>> latency=%u\n",
>> +        dev_name, idle_duration_us, latency_us);
> 
> 1. It is more like a 'debug' rather than 'info', I would change it.
> 2. This is going to be printed for every CPU which has the
> 'thermal-idle' feature in DT. For platforms with many CPUs, it's a lot
> of log entries
> 
>> +
>>       return 0;
>>     out_unregister:
>> @@ -221,12 +232,37 @@ int cpuidle_of_cooling_register(struct
>> device_node *np,
>>    * @drv: a cpuidle driver structure pointer
>>    *
>>    * This function is in charge of creating a cooling device per cpuidle
>> - * driver and register it to thermal framework.
>> + * driver and register it to the thermal framework.
>>    *
>>    * Return: zero on success, or negative value corresponding to the
>>    * error detected in the underlying subsystems.
>>    */
>>   int cpuidle_cooling_register(struct cpuidle_driver *drv)
>>   {
>> -    return cpuidle_of_cooling_register(NULL, drv);
>> +    struct device_node *cooling_node;
>> +    struct device_node *cpu_node;
>> +    int cpu, ret;
>> +
>> +    for_each_cpu(cpu, drv->cpumask) {
>> +
>> +        cpu_node = of_cpu_device_node_get(cpu);
>> +
>> +        cooling_node = of_get_child_by_name(cpu_node, "idle-thermal");
> 
> In DT binding this is 'thermal-idle'.
> 
>> +
>> +        of_node_put(cpu_node);
>> +
>> +        if (!cooling_node)
>> +            continue;
> 
> This 'continue' is suspicious because it won't tell if there was no
> node "idle-thermal" but still the function will return 0. This was
> my case when I tried to enable it on Juno.
> 
> Maybe a debug print that the node hasn't been found would be a
> good idea. Or somehow return different value than 0 taking into
> account that every CPU was skipped.
> 
>> +
>> +        ret = __cpuidle_cooling_register(cooling_node, drv);
>> +
>> +        of_node_put(cooling_node);
>> +
>> +        if (ret)
>> +            return ret;
>> +
>> +        cooling_node = NULL;
>> +    }
>> +
>> +    return 0;
>>   }
>> diff --git a/include/linux/cpu_cooling.h b/include/linux/cpu_cooling.h
>> index 65501d8f9778..4d7b4a303327 100644
>> --- a/include/linux/cpu_cooling.h
>> +++ b/include/linux/cpu_cooling.h
>> @@ -64,18 +64,11 @@ struct cpuidle_driver;
>>     #ifdef CONFIG_CPU_IDLE_THERMAL
>>   int cpuidle_cooling_register(struct cpuidle_driver *drv);
>> -int cpuidle_of_cooling_register(struct device_node *np,
>> -                struct cpuidle_driver *drv);
>>   #else /* CONFIG_CPU_IDLE_THERMAL */
>>   static inline int cpuidle_cooling_register(struct cpuidle_driver *drv)
>>   {
>>       return 0;
>>   }
>> -static inline int cpuidle_of_cooling_register(struct device_node *np,
>> -                          struct cpuidle_driver *drv)
>> -{
>> -    return 0;
>> -}
>>   #endif /* CONFIG_CPU_IDLE_THERMAL */
>>     #endif /* __CPU_COOLING_H__ */
>>
> 
> Apart from that, looks good to me.
> 
> Regards,
> Lukasz


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