Re: [PATCH 07/16] Thermal: Introduce .get_trend() callback.

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Friday, July 20, 2012, Jacob Pan wrote:
> On Thu, 19 Jul 2012 14:31:11 +0800
> Zhang Rui <rui.zhang@intel.com> wrote:
> 
> > tc1 and tc2 are used by OSPM to anticipate the temperature trends.
> > But they are ACPI platform specific concepts.
> > 
> > Introduce .get_trend() as a more general solution.
> > 
> > Signed-off-by: Zhang Rui <rui.zhang@intel.com>
> > ---
> >  drivers/acpi/thermal.c        |   30 ++++++++++++++++++++++++++++++
> >  drivers/thermal/thermal_sys.c |   19 +++++++++++++++++--
> >  include/linux/thermal.h       |    9 +++++++++
> >  3 files changed, 56 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/acpi/thermal.c b/drivers/acpi/thermal.c
> > index a7c97f5..b345646 100644
> > --- a/drivers/acpi/thermal.c
> > +++ b/drivers/acpi/thermal.c
> > @@ -704,6 +704,35 @@ static int thermal_get_crit_temp(struct
> > thermal_zone_device *thermal, return -EINVAL;
> >  }
> >  
> > +static int thermal_get_trend(struct thermal_zone_device *thermal,
> > +				int trip, enum thermal_trend *trend)
> > +{
> > +	struct acpi_thermal *tz = thermal->devdata;
> > +	enum thermal_trip_type type;
> > +	unsigned long trip_temp;
> > +	int i;
> > +
> > +	if (thermal_get_trip_type(thermal, trip, &type))
> > +		return -EINVAL;
> > +
> > +	/* Only PASSIVE trip points need TREND */
> > +	if (type != THERMAL_TRIP_PASSIVE)
> > +		return -EINVAL;
> > +
> > +	/*
> > +	 * tz->temperature has already been updated by generic
> > thermal layer,
> > +	 * before this callback being invoked
> > +	 */
> > +	i = (tz->trips.passive.tc1 * (tz->temperature -
> > tz->last_temperature))
> > +		+ (tz->trips.passive.tc2
> > +		* (tz->temperature - tz->trips.passive.temperature));
> > +
> > +	*trend = i > 0 ? THERMAL_TREND_RAISING :
> > +		(i < 0 ? THERMAL_TREND_DROPPING :
> > THERMAL_TREND_STABLE);
> > +	return 0;
> > +}
> > +
> > +
> >  static int thermal_notify(struct thermal_zone_device *thermal, int
> > trip, enum thermal_trip_type trip_type)
> >  {
> > @@ -832,6 +861,7 @@ static const struct thermal_zone_device_ops
> > acpi_thermal_zone_ops = { .get_trip_type = thermal_get_trip_type,
> >  	.get_trip_temp = thermal_get_trip_temp,
> >  	.get_crit_temp = thermal_get_crit_temp,
> > +	.get_trend = thermal_get_trend,
> >  	.notify = thermal_notify,
> >  };
> >  
> > diff --git a/drivers/thermal/thermal_sys.c
> > b/drivers/thermal/thermal_sys.c index db35300..29b6dba 100644
> > --- a/drivers/thermal/thermal_sys.c
> > +++ b/drivers/thermal/thermal_sys.c
> > @@ -698,6 +698,18 @@ thermal_remove_hwmon_sysfs(struct
> > thermal_zone_device *tz) }
> >  #endif
> >  
> > +static void thermal_get_trend(struct thermal_zone_device *tz,
> > +		int trip, enum thermal_trend *trend)
> > +{
> > +	if (tz->ops->get_trend)
> > +		if (!tz->ops->get_trend(tz, trip, trend))
> > +			return;
> > +
> > +	*trend = tz->temperature >= tz->last_temperature ?
> > +		 THERMAL_TREND_RAISING : THERMAL_TREND_DROPPING;
> I think you are mixing things a little here. ACPI passive cooling
> formula generates a performance trend to guide thermal management,
> which is not a simple temperature trend.
> 
> In case of no .get_trend() present, caller can easily figure out
> temperature trend explicitly instead of getting uninformed information.

thermal_zone_device_passive() (below) is the caller and I don't think it
can really do that.

That said, since thermal_zone_device_passive() seems to me the only caller of
thermal_get_trend(), it might be better to move the code to that function
directly.

Thanks,
Rafael


> > +	return;
> > +}
> > +
> >  static void thermal_zone_device_set_polling(struct
> > thermal_zone_device *tz, int delay)
> >  {
> > @@ -732,6 +744,8 @@ static void thermal_zone_device_passive(struct
> > thermal_zone_device *tz, if (temp >= trip_temp) {
> >  		tz->passive = true;
> >  
> > +		thermal_get_trend(tz, trip, (enum thermal_trend
> > *)&trend); +
> >  		trend = (tz->tc1 * (temp - tz->last_temperature)) +
> >  			(tz->tc2 * (temp - trip_temp));
> >  
> > @@ -1090,6 +1104,9 @@ void thermal_zone_device_update(struct
> > thermal_zone_device *tz) goto leave;
> >  	}
> >  
> > +	tz->last_temperature = tz->temperature;
> > +	tz->temperature = temp;
> > +
> >  	for (count = 0; count < tz->trips; count++) {
> >  		tz->ops->get_trip_type(tz, count, &trip_type);
> >  		tz->ops->get_trip_temp(tz, count, &trip_temp);
> > @@ -1149,8 +1166,6 @@ void thermal_zone_device_update(struct
> > thermal_zone_device *tz) thermal_zone_device_passive(tz, temp,
> > tz->forced_passive, THERMAL_TRIPS_NONE);
> >  
> > -	tz->last_temperature = temp;
> > -
> >  leave:
> >  	if (tz->passive)
> >  		thermal_zone_device_set_polling(tz,
> > tz->passive_delay); diff --git a/include/linux/thermal.h
> > b/include/linux/thermal.h index b355c62..ab656d6 100644
> > --- a/include/linux/thermal.h
> > +++ b/include/linux/thermal.h
> > @@ -44,6 +44,12 @@ enum thermal_trip_type {
> >  	THERMAL_TRIP_CRITICAL,
> >  };
> >  
> > +enum thermal_trend {
> > +	THERMAL_TREND_STABLE, /* temperature is stable */
> > +	THERMAL_TREND_RAISING, /* temperature is raising */
> > +	THERMAL_TREND_DROPPING, /* temperature is dropping */
> > +};
> > +
> >  struct thermal_zone_device_ops {
> >  	int (*bind) (struct thermal_zone_device *,
> >  		     struct thermal_cooling_device *);
> > @@ -65,6 +71,8 @@ struct thermal_zone_device_ops {
> >  	int (*set_trip_hyst) (struct thermal_zone_device *, int,
> >  			      unsigned long);
> >  	int (*get_crit_temp) (struct thermal_zone_device *, unsigned
> > long *);
> > +	int (*get_trend) (struct thermal_zone_device *, int,
> > +			  enum thermal_trend *);
> >  	int (*notify) (struct thermal_zone_device *, int,
> >  		       enum thermal_trip_type);
> >  };
> > @@ -109,6 +117,7 @@ struct thermal_zone_device {
> >  	int tc2;
> >  	int passive_delay;
> >  	int polling_delay;
> > +	int temperature;
> >  	int last_temperature;
> >  	bool passive;
> >  	unsigned int forced_passive;
> 
> 
> 
>