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Message-ID: <CAK44p22hHVcL21B1iy1OnECMd5RCRF8DVh-cNj=6Bmvr5n0yyQ@mail.gmail.com>
Date: Fri, 9 Nov 2012 11:51:33 +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 9 November 2012 09:21, Zhang Rui <rui.zhang@...el.com> wrote:
> On Thu, 2012-11-08 at 11:56 +0530, Amit Kachhap wrote:
>> 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.
>> >
> hmmm,
> I think a more proper way is to set the cooling state to upper limit
> when it overheats and reduce the cooling state step by step when the
> temperature drops.
No actually I was thinking of having a simple governor with a feature
like it only sets to upper level and lower level. Also since the
temperature sensor is capable of interrupting for both increase in
threshold(say 100C) and fall in threshold (say 90C), so polling or
step increments is not needed at all.
Currently stepwise governor governor does that so we might change the
macro name as,
THERMAL_TREND_RAISE_STEP,
THERMAL_TREND_DROP_STEP,
THERMAL_TREND_RAISE_MAX,
THERMAL_TREND_DROP_MAX,
and file step_wise.c can be named as state_wise.c or trend_wise.c.
I am not sure if it is the best way . How do you feel ?
> what do you think?
>
> thanks,
> rui
>
>> > 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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