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

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Date:	Thu, 22 Nov 2012 16:12:31 +0800
From:	Zhang Rui <rui.zhang@...el.com>
To:	Amit 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, 2012-11-22 at 10:11 +0530, Amit Kachhap wrote:
> On 22 November 2012 06:52, 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. 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;
> >>
> > what do you expect to happen if the trend is THERMAL_TREND_RAISE_FULL at
> > this time?
> >
> Hi Rui,
> 
> I suppose this is dethrotle routine and hence this will be called when
> only drop in temperature happens. Also I did not used get_target_state
> here because I thought it might cause regression in the other existing
> thermal drivers(I am not sure) But I guess calling get_target_state is
> the good way to know next target state and is fine if you agree.
> Also one suggestion, 2 functions for throttle/dethrottle can be merged
> as both look same and just get_target_state can be used in that
> function
> 
agree.
patches have been refreshed, please review.

thanks,
rui

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