linux-kernel - Re: [linux-pm] [RFC PATCH 4/5] thermal: cpu_cooling: Release the upper cooling limit checks

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Date:	Mon, 19 May 2014 14:45:28 +0530
From:	amit daniel kachhap <amit.daniel@...sung.com>
To:	Eduardo Valentin <edubezval@...il.com>
Cc:	rjw@...ysocki.net, linux-kernel@...r.kernel.org,
	linux-acpi@...r.kernel.org, linux-pm@...ts.linux-foundation.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [linux-pm] [RFC PATCH 4/5] thermal: cpu_cooling: Release the
 upper cooling limit checks

On Fri, May 16, 2014 at 12:28 AM, Eduardo Valentin <edubezval@...il.com> wrote:
> Hello Amit,
>
> On Thu, May 08, 2014 at 08:07:59PM +0530, Amit Daniel Kachhap wrote:
>> This is required as with addition of cpufreq cooling notifiers
>> mechanism the client can enable some more cooling states at a later
>> point of time. Say when minimum p state is reached then ACPI specific
>> throttling is enabled which may add some more cooling states.
>>
>> Signed-off-by: Amit Daniel Kachhap <amit.daniel@...sung.com>
>> ---
>>  drivers/thermal/step_wise.c    |    2 +-
>>  drivers/thermal/thermal_core.c |    9 +++------
>>  include/linux/thermal.h        |    1 +
>>  3 files changed, 5 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/thermal/step_wise.c b/drivers/thermal/step_wise.c
>> index f251521..7d65617 100644
>> --- a/drivers/thermal/step_wise.c
>> +++ b/drivers/thermal/step_wise.c
>> @@ -72,7 +72,7 @@ static unsigned long get_target_state(struct thermal_instance *instance,
>>               }
>>               break;
>>       case THERMAL_TREND_RAISE_FULL:
>> -             if (throttle)
>> +             if (instance->upper != THERMAL_CSTATE_MAX && throttle)
>>                       next_target = instance->upper;
>>               break;
>>       case THERMAL_TREND_DROPPING:
>> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
>> index 71b0ec0..36bb107 100644
>> --- a/drivers/thermal/thermal_core.c
>> +++ b/drivers/thermal/thermal_core.c
>> @@ -921,7 +921,6 @@ int thermal_zone_bind_cooling_device(struct thermal_zone_device *tz,
>>       struct thermal_instance *pos;
>>       struct thermal_zone_device *pos1;
>>       struct thermal_cooling_device *pos2;
>> -     unsigned long max_state;
>>       int result;
>>
>>       if (trip >= tz->trips || (trip < 0 && trip != THERMAL_TRIPS_NONE))
>> @@ -939,13 +938,11 @@ int thermal_zone_bind_cooling_device(struct thermal_zone_device *tz,
>>       if (tz != pos1 || cdev != pos2)
>>               return -EINVAL;
>>
>> -     cdev->ops->get_max_state(cdev, &max_state);
>> -
>
> I am not sure I follow why we need to release this check. Can't the user
> use the notifier infrastructure and change the max state?
>
> I think I need a better view of use cases where max state would change.
I think i missed adding more description. I will add more details in
the documentation. Actually now with notifier mechanism max state may
change on some condition and at some later time so having this check
here in early stage will not allow taking cooling action for later
dynamic higher cooling states.
>
>
>
>> -     /* lower default 0, upper default max_state */
>> +     /* lower default 0, upper default THERMAL_CSTATE_MAX */
>>       lower = lower == THERMAL_NO_LIMIT ? 0 : lower;
>> -     upper = upper == THERMAL_NO_LIMIT ? max_state : upper;
>> +     upper = upper == THERMAL_NO_LIMIT ? THERMAL_CSTATE_MAX : upper;
>>
>> -     if (lower > upper || upper > max_state)
>> +     if (lower > upper)
>>               return -EINVAL;
>>
>>       dev =
>> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
>> index f7e11c7..3748e6d 100644
>> --- a/include/linux/thermal.h
>> +++ b/include/linux/thermal.h
>> @@ -36,6 +36,7 @@
>>
>>  /* invalid cooling state */
>>  #define THERMAL_CSTATE_INVALID -1UL
>> +#define THERMAL_CSTATE_MAX 1UL
>>
>>  /* No upper/lower limit requirement */
>>  #define THERMAL_NO_LIMIT     THERMAL_CSTATE_INVALID
>> --
>> 1.7.1
>>
>> --
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