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

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Message-ID: <1352354503.2190.7.camel@rzhang1-mobl4>
Date:	Thu, 08 Nov 2012 14:01:43 +0800
From:	Zhang Rui <rui.zhang@...el.com>
To:	Amit Daniel Kachhap <amit.kachhap@...aro.org>
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 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.

I can write such a governor if you do not have time to.

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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