linux-kernel - Re: [PATCH 1/4] thermal: Add new thermal trend type to support quick cooling

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Date:	Thu, 8 Nov 2012 11:56:25 +0530
From:	Amit Kachhap <amit.kachhap@...aro.org>
To:	Zhang Rui <rui.zhang@...el.com>
Cc:	linux-pm@...ts.linux-foundation.org,
	linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
	durgadoss.r@...el.com, lenb@...nel.org, linux-acpi@...r.kernel.org,
	jonghwa3.lee@...sung.com
Subject: Re: [PATCH 1/4] thermal: Add new thermal trend type to support quick cooling

On 8 November 2012 11:31, Zhang Rui <rui.zhang@...el.com> wrote:
> On Thu, 2012-11-08 at 09:56 +0530, Amit Daniel Kachhap wrote:
>> This modification adds 2 new thermal trend type THERMAL_TREND_RAISE_FULL
>> and THERMAL_TREND_DROP_FULL. This thermal trend can be used to quickly
>> jump to the upper or lower cooling level instead of incremental increase
>> or decrease.
>
> IMO, what we need is a new more aggressive cooling governor which always
> uses upper limit when the temperature is raising and lower limit when
> the temperature is dropping.
Yes I agree that a new aggressive governor is the best approach but
then i thought adding a new trend type is a simple solution to achieve
this and since most of the governor logic might be same as the
step-wise governor. I have no objection in doing it through governor.
>
> I can write such a governor if you do not have time to.
ok. thanks
>
> thanks,
> rui
>>  This is needed for temperature sensors which support rising/falling
>> threshold interrupts and polling can be totally avoided.
>>
>
>
>> Signed-off-by: Amit Daniel Kachhap <amit.daniel@...sung.com>
>> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@...aro.org>
>> ---
>>  drivers/thermal/step_wise.c |   19 +++++++++++++++----
>>  include/linux/thermal.h     |    2 ++
>>  2 files changed, 17 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/thermal/step_wise.c b/drivers/thermal/step_wise.c
>> index 1242cff..0d2d8d6 100644
>> --- a/drivers/thermal/step_wise.c
>> +++ b/drivers/thermal/step_wise.c
>> @@ -35,6 +35,10 @@
>>   *       state for this trip point
>>   *    b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
>>   *       state for this trip point
>> + *    c. if the trend is THERMAL_TREND_RAISE_FULL, use highest cooling
>> + *       state for this trip point
>> + *    d. if the trend is THERMAL_TREND_DROP_FULL, use lowest cooling
>> + *       state for this trip point
>>   */
>>  static unsigned long get_target_state(struct thermal_instance *instance,
>>                                       enum thermal_trend trend)
>> @@ -50,7 +54,10 @@ static unsigned long get_target_state(struct thermal_instance *instance,
>>       } else if (trend == THERMAL_TREND_DROPPING) {
>>               cur_state = cur_state > instance->lower ?
>>                           (cur_state - 1) : instance->lower;
>> -     }
>> +     } else if (trend == THERMAL_TREND_RAISE_FULL)
>> +             cur_state = instance->upper;
>> +     else if (trend == THERMAL_TREND_DROP_FULL)
>> +             cur_state = instance->lower;
>>
>>       return cur_state;
>>  }
>> @@ -87,7 +94,8 @@ static void update_instance_for_throttle(struct thermal_zone_device *tz,
>>  }
>>
>>  static void update_instance_for_dethrottle(struct thermal_zone_device *tz,
>> -                             int trip, enum thermal_trip_type trip_type)
>> +                             int trip, enum thermal_trip_type trip_type,
>> +                             enum thermal_trend trend)
>>  {
>>       struct thermal_instance *instance;
>>       struct thermal_cooling_device *cdev;
>> @@ -101,7 +109,10 @@ static void update_instance_for_dethrottle(struct thermal_zone_device *tz,
>>               cdev = instance->cdev;
>>               cdev->ops->get_cur_state(cdev, &cur_state);
>>
>> -             instance->target = cur_state > instance->lower ?
>> +             if (trend == THERMAL_TREND_DROP_FULL)
>> +                     instance->target = instance->lower;
>> +             else
>> +                     instance->target = cur_state > instance->lower ?
>>                           (cur_state - 1) : THERMAL_NO_TARGET;
>>
>>               /* Deactivate a passive thermal instance */
>> @@ -133,7 +144,7 @@ static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
>>       if (tz->temperature >= trip_temp)
>>               update_instance_for_throttle(tz, trip, trip_type, trend);
>>       else
>> -             update_instance_for_dethrottle(tz, trip, trip_type);
>> +             update_instance_for_dethrottle(tz, trip, trip_type, trend);
>>
>>       mutex_unlock(&tz->lock);
>>  }
>> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
>> index 807f214..8bce3ec 100644
>> --- a/include/linux/thermal.h
>> +++ b/include/linux/thermal.h
>> @@ -68,6 +68,8 @@ enum thermal_trend {
>>       THERMAL_TREND_STABLE, /* temperature is stable */
>>       THERMAL_TREND_RAISING, /* temperature is raising */
>>       THERMAL_TREND_DROPPING, /* temperature is dropping */
>> +     THERMAL_TREND_RAISE_FULL, /* Apply highest cooling action*/
>> +     THERMAL_TREND_DROP_FULL, /* Apply lowest cooling action*/
>>  };
>>
>>  /* Events supported by Thermal Netlink */
>
>
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