RE: [PATCH 1/4] thermal: Add new thermal trend type to supportquick cooling

From: R, Durgadoss
Date: Fri Nov 09 2012 - 00:16:09 EST


Hi Rui/Amit,

Sorry for the late response..

> -----Original Message-----
> From: Amit Kachhap [mailto:amit.kachhap@xxxxxxxxxx]
> Sent: Thursday, November 08, 2012 11:56 AM
> To: Zhang, Rui
> Cc: linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx; linux-samsung-
> soc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; R, Durgadoss;
> lenb@xxxxxxxxxx; linux-acpi@xxxxxxxxxxxxxxx; jonghwa3.lee@xxxxxxxxxxx
> 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@xxxxxxxxx> 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.

Yes, this sounds like a feasible and not-so-complicated implementation for now.
In future, if we see a lot of drivers requiring this sudden raise/drop functionality,
at that time we can introduce an 'aggressive' governor.

Thanks,
Durga

> >
> > 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@xxxxxxxxxxx>
> >> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@xxxxxxxxxx>
> >> ---
> >> 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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