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SubjectRe: [linux-pm] [RFC PATCH 1/2] thermal: Add a new trip type to use cooling device instance number
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Hi Rob,

I got your point. The main idea of doing like this is to keep the
cooling implementation independent from thermal zone
algorithms(thermal_sys.c). But binding freq_tab index to the trip
numbers may be not be bad idea. I will give more thought into it in
the next patchset.

Regards,
Amit D

On 11 January 2012 13:42, Rob Lee <rob.lee@linaro.org> wrote:
> Hey Amit/Vincent,
>
> It appears that with this implementation the STATE_ACTIVE trip number
> used will also be the index of the cool_freq_tab used.  If that is
> true, then perhaps a common structure would be beneficial that links
> each STATE_ACTIVE trip point with its corresponding cooling data.
>
> BR,
> Rob
>
> On Tue, Dec 20, 2011 at 11:11 PM, Amit Kachhap <amit.kachhap@linaro.org> wrote:
>>  Hi Vincent,
>>
>> Thanks for the review.
>> Well actually your are correct that current temperature and last
>> temperature can be used to increase or decrease the cpu frequency. But
>> this has to be done again in cooling devices so to make the cooling
>> devices generic and to avoid the temperature comparison again this new
>> trip type passes the cooling device instance id.
>> Also about your queries that this may add dependency between trip
>> index and cooling state. This is actually needed and this dependency
>> is created when the cooling device is binded with trip points(For
>> cpufreq type cooling device just the instance of cooling device is
>> associated with trip points). More over the existing PASSIVE cooling
>> trip type does the same thing and iterates across all the cooling
>> state.
>>
>>  Thanks,
>>  Amit Daniel
>>>
>>> On 20 December 2011 18:07, Vincent Guittot <vincent.guittot@linaro.org> wrote:
>>>>
>>>> Hi Amit,
>>>>
>>>> I'm not sure that using the trip index for setting the state of a
>>>> cooling device is a generic solution because you are adding a
>>>> dependency between the trip index and the cooling device state that
>>>> might be difficult to handle. This dependency implies that a cooling
>>>> device like cpufreq_cooling_device must be registered in the 1st trips
>>>> of a thermal_zone which is not possible when we want to register 2
>>>> cpufreq_cooling_devices in the same thermal_zone.
>>>> You should only rely on the current and last temperatures to detect if
>>>> a trip_temp has been crossed and you should increase or decrease the
>>>> current state of the cooling device accordingly.
>>>>
>>>> something like below should work with cpufreq_cooling_device and will
>>>> not add any constraint on the trip index. The state of a cooling
>>>> device is increased/decreased once for each trip
>>>>
>>>> +               case THERMAL_TRIP_STATE_ACTIVE:
>>>> +                       list_for_each_entry(instance, &tz->cooling_devices,
>>>> +                                           node) {
>>>> +                               if (instance->trip != count)
>>>> +                                       continue;
>>>> +
>>>> +                               cdev = instance->cdev;
>>>> +
>>>> +                               if ((temp >= trip_temp)
>>>> +                                       && (trip_temp > tz->last_temperature)) {
>>>> +                                       cdev->ops->get_max_state(cdev,
>>>> +                                                       &max_state);
>>>> +                                       cdev->ops->get_cur_state(cdev,
>>>> +                                                       &current_state);
>>>> +                                       if (++current_state <= max_state)
>>>> +                                               cdev->ops->set_cur_state(cdev,
>>>> +                                                               current_state);
>>>> +                               }
>>>> +                               else if ((temp < trip_temp)
>>>> +                                       && (trip_temp <= tz->last_temperature)) {
>>>> +                                       cdev->ops->get_cur_state(cdev,
>>>> +                                                       &current_state);
>>>> +                                       if (current_state > 0)
>>>> +                                               cdev->ops->set_cur_state(cdev,
>>>> +                                                               --current_state);
>>>> +                       }
>>>> +                       break;
>>>>
>>>> Regards,
>>>> Vincent
>>>>
>>>> On 13 December 2011 16:13, Amit Daniel Kachhap <amit.kachhap@linaro.org> wrote:
>>>> > This patch adds a new trip type THERMAL_TRIP_STATE_ACTIVE. This
>>>> > trip behaves same as THERMAL_TRIP_ACTIVE but also passes the cooling
>>>> > device instance number. This helps the cooling device registered as
>>>> > different instances to perform appropriate cooling action decision in
>>>> > the set_cur_state call back function.
>>>> >
>>>> > Also since the trip temperature's are in ascending order so some logic
>>>> > is put in place to skip the un-necessary checks.
>>>> >
>>>> > Signed-off-by: Amit Daniel Kachhap <amit.kachhap@linaro.org>
>>>> > ---
>>>> >  Documentation/thermal/sysfs-api.txt |    4 ++--
>>>> >  drivers/thermal/thermal_sys.c       |   27 ++++++++++++++++++++++++++-
>>>> >  include/linux/thermal.h             |    1 +
>>>> >  3 files changed, 29 insertions(+), 3 deletions(-)
>>>> >
>>>> > diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt
>>>> > index b61e46f..5c1d44e 100644
>>>> > --- a/Documentation/thermal/sysfs-api.txt
>>>> > +++ b/Documentation/thermal/sysfs-api.txt
>>>> > @@ -184,8 +184,8 @@ trip_point_[0-*]_temp
>>>> >
>>>> >  trip_point_[0-*]_type
>>>> >        Strings which indicate the type of the trip point.
>>>> > -       E.g. it can be one of critical, hot, passive, active[0-*] for ACPI
>>>> > -       thermal zone.
>>>> > +       E.g. it can be one of critical, hot, passive, active[0-1],
>>>> > +       state-active[0-*] for ACPI thermal zone.
>>>> >        RO, Optional
>>>> >
>>>> >  cdev[0-*]
>>>> > diff --git a/drivers/thermal/thermal_sys.c b/drivers/thermal/thermal_sys.c
>>>> > index dd9a574..72b1ab3 100644
>>>> > --- a/drivers/thermal/thermal_sys.c
>>>> > +++ b/drivers/thermal/thermal_sys.c
>>>> > @@ -192,6 +192,8 @@ trip_point_type_show(struct device *dev, struct device_attribute *attr,
>>>> >                return sprintf(buf, "passive\n");
>>>> >        case THERMAL_TRIP_ACTIVE:
>>>> >                return sprintf(buf, "active\n");
>>>> > +       case THERMAL_TRIP_STATE_ACTIVE:
>>>> > +               return sprintf(buf, "state-active\n");
>>>> >        default:
>>>> >                return sprintf(buf, "unknown\n");
>>>> >        }
>>>> > @@ -1035,7 +1037,7 @@ EXPORT_SYMBOL(thermal_cooling_device_unregister);
>>>> >  void thermal_zone_device_update(struct thermal_zone_device *tz)
>>>> >  {
>>>> >        int count, ret = 0;
>>>> > -       long temp, trip_temp;
>>>> > +       long temp, trip_temp, max_state, last_trip_change = 0;
>>>> >        enum thermal_trip_type trip_type;
>>>> >        struct thermal_cooling_device_instance *instance;
>>>> >        struct thermal_cooling_device *cdev;
>>>> > @@ -1086,6 +1088,29 @@ void thermal_zone_device_update(struct thermal_zone_device *tz)
>>>> >                                        cdev->ops->set_cur_state(cdev, 0);
>>>> >                        }
>>>> >                        break;
>>>> > +               case THERMAL_TRIP_STATE_ACTIVE:
>>>> > +                       list_for_each_entry(instance, &tz->cooling_devices,
>>>> > +                                           node) {
>>>> > +                               if (instance->trip != count)
>>>> > +                                       continue;
>>>> > +
>>>> > +                               if (temp <= last_trip_change)
>>>> > +                                       continue;
>>>> > +
>>>> > +                               cdev = instance->cdev;
>>>> > +                               cdev->ops->get_max_state(cdev, &max_state);
>>>> > +
>>>> > +                               if ((temp >= trip_temp) &&
>>>> > +                                               ((count + 1) <= max_state))
>>>> > +                                       cdev->ops->set_cur_state(cdev,
>>>> > +                                                               count + 1);
>>>> > +                               else if ((temp < trip_temp) &&
>>>> > +                                                       (count <= max_state))
>>>> > +                                       cdev->ops->set_cur_state(cdev, count);
>>>> > +
>>>> > +                               last_trip_change = trip_temp;
>>>> > +                       }
>>>> > +                       break;
>>>> >                case THERMAL_TRIP_PASSIVE:
>>>> >                        if (temp >= trip_temp || tz->passive)
>>>> >                                thermal_zone_device_passive(tz, temp,
>>>> > diff --git a/include/linux/thermal.h b/include/linux/thermal.h
>>>> > index 47b4a27..d7d0a27 100644
>>>> > --- a/include/linux/thermal.h
>>>> > +++ b/include/linux/thermal.h
>>>> > @@ -42,6 +42,7 @@ enum thermal_trip_type {
>>>> >        THERMAL_TRIP_PASSIVE,
>>>> >        THERMAL_TRIP_HOT,
>>>> >        THERMAL_TRIP_CRITICAL,
>>>> > +       THERMAL_TRIP_STATE_ACTIVE,
>>>> >  };
>>>> >
>>>> >  struct thermal_zone_device_ops {
>>>> > --
>>>> > 1.7.1
>>>> >
>>>> > _______________________________________________
>>>> > linux-pm mailing list
>>>> > linux-pm@lists.linux-foundation.org
>>>> > https://lists.linuxfoundation.org/mailman/listinfo/linux-pm
>>>
>>>
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