Re: [PATCH] thermal: add interface to support tune governor in run-time

[Eduardo Valentin <eduardo.valentin-l0cyMroinI0@public.gmane.org>]

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On 08-01-2014 05:07, Wei Ni wrote:
> The governers are not static, so added a new function
> thermal_update_governor() to update a new one and throw away
> old ones in run-time. And added start/stop callback to tuning governor
> parameters at any time.

Please provide better explanation of why you need this. Providing use
cases is good start.

> 
> Signed-off-by: Wei Ni <wni-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> ---
>  drivers/thermal/thermal_core.c |  103 ++++++++++++++++++++++++++++++++++++----
>  drivers/thermal/thermal_core.h |    1 +
>  include/linux/thermal.h        |   11 +++++
>  3 files changed, 106 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index 89e0637..be93f43 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -93,10 +93,17 @@ int thermal_register_governor(struct thermal_governor *governor)
>  			name = pos->tzp->governor_name;
>  		else
>  			name = DEFAULT_THERMAL_GOVERNOR;
> -		if (!strnicmp(name, governor->name, THERMAL_NAME_LENGTH))
> +		if (!strnicmp(name, governor->name, THERMAL_NAME_LENGTH)) {
> +			if (governor->start) {
> +				err = governor->start(pos);
> +				if (err < 0)
> +					goto exit;
> +			}
>  			pos->governor = governor;
> +		}
>  	}
>  
> +exit:
>  	mutex_unlock(&thermal_list_lock);
>  	mutex_unlock(&thermal_governor_lock);
>  
> @@ -119,8 +126,11 @@ void thermal_unregister_governor(struct thermal_governor *governor)
>  
>  	list_for_each_entry(pos, &thermal_tz_list, node) {
>  		if (!strnicmp(pos->governor->name, governor->name,
> -						THERMAL_NAME_LENGTH))
> +						THERMAL_NAME_LENGTH)) {
> +			if (pos->governor->stop)
> +				pos->governor->stop(pos);
>  			pos->governor = NULL;
> +		}
>  	}
>  
>  	mutex_unlock(&thermal_list_lock);
> @@ -130,6 +140,49 @@ exit:
>  	return;
>  }
>  
> +/**
> + * thermal_update_governor() - update the thermal zone device's governor
> + * to a new one.
> + * @tzd: pointer of thermal zone device, which need to update governor.
> + * @name: thermal zone name to fetch the temperature
> + *
> + * Return: On success returns 0, an error code otherwise
> + */
> +int thermal_update_governor(struct thermal_zone_device *tzd,
> +			    const char *name)
> +{
> +	struct thermal_governor *old_gov, *new_gov;
> +	int ret = 0;
> +
> +	mutex_lock(&thermal_governor_lock);
> +
> +	new_gov = __find_governor(name);
> +	if (!new_gov) {
> +		ret = -EINVAL;
> +		goto exit;
> +	}
> +
> +	old_gov = tzd->governor;
> +
> +	if (old_gov && old_gov->stop)
> +		old_gov->stop(tzd);
> +
> +	if (new_gov->start) {
> +		ret = new_gov->start(tzd);
> +		if (ret < 0) {
> +			if (old_gov && old_gov->start)
> +				old_gov->start(tzd);
> +			goto exit;
> +		}
> +	}
> +
> +	tzd->governor = new_gov;
> +
> +exit:
> +	mutex_unlock(&thermal_governor_lock);
> +	return ret;
> +}
> +
>  static int get_idr(struct idr *idr, struct mutex *lock, int *id)
>  {
>  	int ret;
> @@ -734,22 +787,17 @@ policy_store(struct device *dev, struct device_attribute *attr,
>  {
>  	int ret = -EINVAL;
>  	struct thermal_zone_device *tz = to_thermal_zone(dev);
> -	struct thermal_governor *gov;
>  	char name[THERMAL_NAME_LENGTH];
>  
>  	snprintf(name, sizeof(name), "%s", buf);
>  
> -	mutex_lock(&thermal_governor_lock);
> -
> -	gov = __find_governor(strim(name));
> -	if (!gov)
> +	ret = thermal_update_governor(tz, strim(name));
> +	if (ret < 0)
>  		goto exit;
>  
> -	tz->governor = gov;
>  	ret = count;
>  
>  exit:
> -	mutex_unlock(&thermal_governor_lock);
>  	return ret;
>  }
>  
> @@ -761,6 +809,24 @@ policy_show(struct device *dev, struct device_attribute *devattr, char *buf)
>  	return sprintf(buf, "%s\n", tz->governor->name);
>  }
>  
> +static ssize_t
> +available_policies_show(struct device *dev, struct device_attribute *devattr,
> +			char *buf)
> +{
> +	struct thermal_governor *pos;
> +	ssize_t count = 0;
> +
> +	mutex_lock(&thermal_governor_lock);
> +
> +	list_for_each_entry(pos, &thermal_governor_list, governor_list)
> +		count += sprintf(buf + count, "%s ", pos->name);
> +	count += sprintf(buf + count, "\n");
> +
> +	mutex_unlock(&thermal_governor_lock);
> +
> +	return count;
> +}
> +

Adding an ABI requires documenting it under Documentation/

Besides, I believe this is a matter for a different patch than this one.

>  #ifdef CONFIG_THERMAL_EMULATION
>  static ssize_t
>  emul_temp_store(struct device *dev, struct device_attribute *attr,
> @@ -794,6 +860,7 @@ static DEVICE_ATTR(temp, 0444, temp_show, NULL);
>  static DEVICE_ATTR(mode, 0644, mode_show, mode_store);
>  static DEVICE_ATTR(passive, S_IRUGO | S_IWUSR, passive_show, passive_store);
>  static DEVICE_ATTR(policy, S_IRUGO | S_IWUSR, policy_show, policy_store);
> +static DEVICE_ATTR(available_policies, S_IRUGO, available_policies_show, NULL);
>  
>  /* sys I/F for cooling device */
>  #define to_cooling_device(_dev)	\
> @@ -1527,6 +1594,11 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
>  	if (result)
>  		goto unregister;
>  
> +	/* Create available_policies attribute */
> +	result = device_create_file(&tz->device, &dev_attr_available_policies);
> +	if (result)
> +		goto unregister;
> +
>  	/* Update 'this' zone's governor information */
>  	mutex_lock(&thermal_governor_lock);
>  
> @@ -1535,6 +1607,12 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
>  	else
>  		tz->governor = __find_governor(DEFAULT_THERMAL_GOVERNOR);
>  
> +	if (tz->governor->start) {
> +		result = tz->governor->start(tz);
> +		if (result < 0)
> +			tz->governor = NULL;
> +	}
> +
>  	mutex_unlock(&thermal_governor_lock);
>  
>  	if (!tz->tzp || !tz->tzp->no_hwmon) {
> @@ -1561,6 +1639,9 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
>  		return tz;
>  
>  unregister:
> +	if (tz->governor && tz->governor->stop)
> +		tz->governor->stop(tz);
> +	tz->governor = NULL;
>  	release_idr(&thermal_tz_idr, &thermal_idr_lock, tz->id);
>  	device_unregister(&tz->device);
>  	return ERR_PTR(result);
> @@ -1622,7 +1703,11 @@ void thermal_zone_device_unregister(struct thermal_zone_device *tz)
>  	if (tz->ops->get_mode)
>  		device_remove_file(&tz->device, &dev_attr_mode);
>  	device_remove_file(&tz->device, &dev_attr_policy);
> +	device_remove_file(&tz->device, &dev_attr_available_policies);
>  	remove_trip_attrs(tz);
> +
> +	if (tz->governor && tz->governor->stop)
> +		tz->governor->stop(tz);
>  	tz->governor = NULL;
>  
>  	thermal_remove_hwmon_sysfs(tz);
> diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_core.h
> index 3db339f..89bcfe7 100644
> --- a/drivers/thermal/thermal_core.h
> +++ b/drivers/thermal/thermal_core.h
> @@ -52,6 +52,7 @@ struct thermal_instance {
>  
>  int thermal_register_governor(struct thermal_governor *);
>  void thermal_unregister_governor(struct thermal_governor *);
> +int thermal_update_governor(struct thermal_zone_device *, const char *);
>  
>  #ifdef CONFIG_THERMAL_GOV_STEP_WISE
>  int thermal_gov_step_wise_register(void);
> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> index 37e4e03..ad9ab14 100644
> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -178,6 +178,7 @@ struct thermal_zone_device {
>  	struct thermal_zone_device_ops *ops;
>  	const struct thermal_zone_params *tzp;
>  	struct thermal_governor *governor;
> +	void *governor_data;
>  	struct list_head thermal_instances;
>  	struct idr idr;
>  	struct mutex lock; /* protect thermal_instances list */
> @@ -188,6 +189,15 @@ struct thermal_zone_device {
>  /* Structure that holds thermal governor information */
>  struct thermal_governor {
>  	char name[THERMAL_NAME_LENGTH];
> +
> +	/*
> +	 * The start and stop operations will be called when thermal zone is
> +	 * registered and when change governor via sysfs or driver in running
> +	 * time.
> +	 */
> +	int (*start)(struct thermal_zone_device *tz);
> +	void (*stop)(struct thermal_zone_device *tz);
> +

But no explanation why a governor would need it is provided..


>  	int (*throttle)(struct thermal_zone_device *tz, int trip);
>  	struct list_head	governor_list;
>  };
> @@ -235,6 +245,7 @@ struct thermal_zone_params {
>  	 */
>  	bool no_hwmon;
>  
> +	void *governor_params;
>  	int num_tbps;	/* Number of tbp entries */
>  	struct thermal_bind_params *tbp;
>  };
> 


-- 
You have got to be excited about what you are doing. (L. Lamport)

Eduardo Valentin


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