linux-kernel - Re: [PATCH v2 01/14] thermal/core: Change thermal_zone_ops to thermal_sensor

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Date:   Tue, 17 May 2022 09:50:54 -0700
From:   srinivas pandruvada <srinivas.pandruvada@...ux.intel.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...exp.org>
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Subject: Re: [PATCH v2 01/14] thermal/core: Change thermal_zone_ops to
 thermal_sensor_ops

On Tue, 2022-05-17 at 17:42 +0200, Rafael J. Wysocki wrote:
> On Sat, May 7, 2022 at 2:55 PM Daniel Lezcano
> <daniel.lezcano@...exp.org> wrote:
> > 
> > A thermal zone is software abstraction of a sensor associated with
> > properties and cooling devices if any.
> > 
> > The fact that we have thermal_zone and thermal_zone_ops mixed is
> > confusing and does not clearly identify the different components
> > entering in the thermal management process. A thermal zone appears
> > to
> > be a sensor while it is not.
> 
> Well, the majority of the operations in thermal_zone_ops don't apply
> to thermal sensors.  For example, ->set_trips(), ->get_trip_type(),
> ->get_trip_temp().
> 
In past we discussed adding thermal sensor sysfs with threshold to
notify temperature.

So sensor can have set/get_threshold() functions instead of the
set/get_trip for zones.

Like we have /sys/class/thermal_zone* we can have
/sys/class/thermal_sensor*.

Thermal sensor(s) are bound to  thermal zones. This can also include
multiple sensors in a zone and can create a virtual sensor also.

Thanks,
Srinivas

> > In order to set the scene for multiple thermal sensors aggregated
> > into
> > a single thermal zone. Rename the thermal_zone_ops to
> > thermal_sensor_ops, that will appear clearyl the thermal zone is
> > not a
> > sensor but an abstraction of one [or multiple] sensor(s).
> 
> So I'm not convinced that the renaming mentioned above is
> particularly
> clean either.
> 
> IMV the way to go would be to split the thermal sensor operations,
> like ->get_temp(), out of thermal_zone_ops.
> 
> But then it is not clear what a thermal zone with multiple sensors in
> it really means.  I guess it would require an aggregation function to
> combine the thermal sensors in it that would produce an effective
> temperature to check against the trip points.
> 
> Honestly, I don't think that setting a separate set of trips for each
> sensor in a thermal zone would make a lot of sense.