linux-kernel - Re: [PATCH 1/2] thermal: core: Move thermal_cdev

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Message-ID: <0c9796c5-95fe-0349-d128-393da9b344d6@linaro.org>
Date:   Fri, 10 Apr 2020 13:26:25 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Zhang Rui <rui.zhang@...el.com>
Cc:     linux-kernel@...r.kernel.org, amit.kucheria@...durent.com,
        "open list:THERMAL" <linux-pm@...r.kernel.org>
Subject: Re: [PATCH 1/2] thermal: core: Move thermal_cdev_update next to
 updated=false

On 10/04/2020 12:14, Zhang Rui wrote:
> Hi, Daniel,
> 
> On Thu, 2020-04-09 at 17:15 +0200, Daniel Lezcano wrote:
>> The call to the thermal_cdev_update() function is done after browsing
>> the thermal instances which sets the updated flag by browsing them
>> again.
>>
>> Instead of doing this, let's move the call right after setting the
>> cooling device 'updated' flag as it is done in the other governors.
> 
> The reason we do this in two steps is that we want to avoid redundant
> cooling device state changes.
> 
> Further more, I think it is better to move the thermal_cdev_update out
> of .throllte() callback, to thermal_zone_device_update(). So that we do
> not need to update the cooling device for each trip point.
> 
> is there any specific reason we need to do thermal_cdev_update() for
> every potential change?

I agree we can go further and move the cooling device update in the
thermal_zone_device_update() by letting the throttle callback let us
know an update is needed with the return value.

Makes sense to provide more changes on top of those two patches ?

>> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
>> ---
>>  drivers/thermal/gov_bang_bang.c | 10 +---------
>>  drivers/thermal/step_wise.c     | 10 +---------
>>  2 files changed, 2 insertions(+), 18 deletions(-)
>>
>> diff --git a/drivers/thermal/gov_bang_bang.c
>> b/drivers/thermal/gov_bang_bang.c
>> index 991a1c54296d..c292a69845bb 100644
>> --- a/drivers/thermal/gov_bang_bang.c
>> +++ b/drivers/thermal/gov_bang_bang.c
>> @@ -64,6 +64,7 @@ static void thermal_zone_trip_update(struct
>> thermal_zone_device *tz, int trip)
>>  		mutex_lock(&instance->cdev->lock);
>>  		instance->cdev->updated = false; /* cdev needs update
>> */
>>  		mutex_unlock(&instance->cdev->lock);
>> +		thermal_cdev_update(instance->cdev);
>>  	}
>>  
>>  	mutex_unlock(&tz->lock);
>> @@ -98,17 +99,8 @@ static void thermal_zone_trip_update(struct
>> thermal_zone_device *tz, int trip)
>>   */
>>  static int bang_bang_control(struct thermal_zone_device *tz, int
>> trip)
>>  {
>> -	struct thermal_instance *instance;
>> -
>>  	thermal_zone_trip_update(tz, trip);
>>  
>> -	mutex_lock(&tz->lock);
>> -
>> -	list_for_each_entry(instance, &tz->thermal_instances, tz_node)
>> -		thermal_cdev_update(instance->cdev);
>> -
>> -	mutex_unlock(&tz->lock);
>> -
>>  	return 0;
>>  }
>>  
>> diff --git a/drivers/thermal/step_wise.c
>> b/drivers/thermal/step_wise.c
>> index 2ae7198d3067..298eedac0293 100644
>> --- a/drivers/thermal/step_wise.c
>> +++ b/drivers/thermal/step_wise.c
>> @@ -167,6 +167,7 @@ static void thermal_zone_trip_update(struct
>> thermal_zone_device *tz, int trip)
>>  		mutex_lock(&instance->cdev->lock);
>>  		instance->cdev->updated = false; /* cdev needs update
>> */
>>  		mutex_unlock(&instance->cdev->lock);
>> +		thermal_cdev_update(instance->cdev);
>>  	}
>>  
>>  	mutex_unlock(&tz->lock);
>> @@ -185,20 +186,11 @@ static void thermal_zone_trip_update(struct
>> thermal_zone_device *tz, int trip)
>>   */
>>  static int step_wise_throttle(struct thermal_zone_device *tz, int
>> trip)
>>  {
>> -	struct thermal_instance *instance;
>> -
>>  	thermal_zone_trip_update(tz, trip);
>>  
>>  	if (tz->forced_passive)
>>  		thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);
>>  
>> -	mutex_lock(&tz->lock);
>> -
>> -	list_for_each_entry(instance, &tz->thermal_instances, tz_node)
>> -		thermal_cdev_update(instance->cdev);
>> -
>> -	mutex_unlock(&tz->lock);
>> -
>>  	return 0;
>>  }
>>  
> 


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