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Date: Thu, 28 Aug 2014 09:21:37 -0400
From: Eduardo Valentin <edubezval@...il.com>
To: Wei Ni <wni@...dia.com>
Cc: khali@...ux-fr.org, linux@...ck-us.net, swarren@...dotorg.org,
lm-sensors@...sensors.org, linux-tegra@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/4] thermal: add more description for thermal-zones
Hello Wei,
On Thu, Aug 28, 2014 at 09:50:01AM +0800, Wei Ni wrote:
> On 08/27/2014 09:32 PM, Eduardo Valentin wrote:
> > Hello Wei,
> >
> > On Wed, Aug 27, 2014 at 10:54:07AM +0800, Wei Ni wrote:
> >> On 08/26/2014 08:12 PM, Eduardo Valentin wrote:
> >>> On Tue, Aug 26, 2014 at 10:17:29AM +0800, Wei Ni wrote:
> >>>> On 08/25/2014 07:07 PM, Eduardo Valentin wrote:
> >>>>> Hello Wei Ni,
> >>>>>
> >>>>> On Mon, Aug 25, 2014 at 02:29:47PM +0800, Wei Ni wrote:
> >>>>>> Add more description for the "polling-delay" property.
> >>>>>> Set "trips" and "cooling maps" as optional property, because
> >>>>>> if missing these two sub-nodes, the thermal zone device still
> >>>>>> work properly.
> >>>>>>
> >>>>>> Signed-off-by: Wei Ni <wni@...dia.com>
> >>>>>> ---
> >>>>>> Documentation/devicetree/bindings/thermal/thermal.txt | 10 ++++++----
> >>>>>> 1 file changed, 6 insertions(+), 4 deletions(-)
> >>>>>>
> >>>>>> diff --git a/Documentation/devicetree/bindings/thermal/thermal.txt b/Documentation/devicetree/bindings/thermal/thermal.txt
> >>>>>> index f5db6b7..e3d3ed9 100644
> >>>>>> --- a/Documentation/devicetree/bindings/thermal/thermal.txt
> >>>>>> +++ b/Documentation/devicetree/bindings/thermal/thermal.txt
> >>>>>> @@ -136,8 +136,8 @@ containing trip nodes and one sub-node containing all the zone cooling maps.
> >>>>>>
> >>>>>> Required properties:
> >>>>>> - polling-delay: The maximum number of milliseconds to wait between polls
> >>>>>> - Type: unsigned when checking this thermal zone.
> >>>>>> - Size: one cell
> >>>>>> + Type: unsigned when checking this thermal zone. If this value is 0, the
> >>>>>> + Size: one cell driver will not run polling queue, but just cancel it.
> >>>>>>
> >>>>>
> >>>>> The description above is specific to Linux kernel implementation
> >>>>> nomenclature. DT description needs to be OS agnostic.
> >>>>>
> >>>>>> - polling-delay-passive: The maximum number of milliseconds to wait
> >>>>>> Type: unsigned between polls when performing passive cooling.
> >>>>>> @@ -148,14 +148,16 @@ Required properties:
> >>>>>> phandles + sensor
> >>>>>> specifier
> >>>>>>
> >>>>>> +Optional property:
> >>>>>> - trips: A sub-node which is a container of only trip point nodes
> >>>>>> Type: sub-node required to describe the thermal zone.
> >>>>>>
> >>>>>> - cooling-maps: A sub-node which is a container of only cooling device
> >>>>>> Type: sub-node map nodes, used to describe the relation between trips
> >>>>>> - and cooling devices.
> >>>>>> + and cooling devices. If missing the "trips" property,
> >>>>>> + This sub-node will not be parsed, because no trips can
> >>>>>> + be bound to cooling devices.
> >>>>>
> >>>>> Do you mean if the thermal zone misses the "trips" property? Actually,
> >>>>> the binding describes both, cooling-maps and trips, as required
> >>>>> properties. Thus, both needs to be in place to consider the thermal zone
> >>>>> as a proper described zone.
> >>>>
> >>>> I moved the "trips" and "cooling-maps" to optional property, because if
> >>>> missing these two properties, the thermal zone devices still can be
> >>>> registered, and the driver can work properly, it has the basic function,
> >>>> can read temperature from thermal sysfs, although it doesn't have trips
> >>>> and bind with cooling devices.
> >>>
> >>>
> >>> If a thermal zone is used only for monitoring, then I believe it lost
> >>> its purpose. As Maybe a different framework shall be used, such as hwmon,
> >>> for instance?
> >>
> >> Yes, if we only use it for monitoring, we can use hwmon. But we have
> >> more functions base on these two thermal zone devices. We have a
> >> skin-temperature driver, which used nct1008's remote and local
> >> temperatures to estimator the skin temperature. As you know the thermal
> >> framework is more powerful, the remote/local sensors can be register as
> >> thermal zone, then the skin-temp driver can use thermal_zone_get_temp()
> >> to read their temperatures and then estimator skin's temp. We also will
> >> set trips and cooling devices for this skin-temp.
> >
> > In this case, don't you think it would make sense to create a thermal
> > zone for the skin temperature and add the required sensors (including
> > the nct1008) in it?
>
> Hi, Eduardo
> Yes, we will create a thermal zone for the skin-temp driver and add the
> required sensors in it, but in here we want to register these required
> sensors as thermal zone devices, then the thermal framework can export
> functions to read these sensors temperature. If use hwmon framework, it
> can't export nct1008's internal sensors, such as remote/local sensors,
> and no exported functions to read these temperatures. If we doesn't use
> the thermal/of-thermal framework, we have to develop a new framework to
> parse those sensor nodes, and I think this new one may only have slight
> difference with current thermal framework.
> If we set those two properties as optional property, then we can use it
> in this case simply.
>
> The skin-temp nodes will something like this:
>
> skin_temp: therm-est {
> compatible = "nvidia,tegra124-therm-est";
>
> #thermal-sensor-cells = <0>;
>
> sub-devs {
> dev@0 {
> /* we need to register nct1008_remote as thermal zone devices, so that
> it's easy to handle it by using thermal framework's exported functions. */
> dev = <&nct1008_remote>;
> };
> dev@1 {
> dev = <&nct1008_local>;
> };
> };
> };
>
> thermal-zones {
> skin-therm {
> polling-delay-passive = <15000>
> polling-delay = <0>;
>
> thermal-sensors = <&skin_temp>;
The binding allows you to add several sensors in one thermal zone.
Please have a look on the example (c) of the thermal.txt binding
description. It might be that what you want to do is actually:
thermal-sensors = <&ntc1008_local>,
<&ntc1008_remote>;
>
> trips {
> };
> cooling-maps {
> };
> };
> };
>
> Wei.
> >
> >>
> >> Wei.
> >>
> >>>
> >>> The purpose of a thermal zone is to describe thermal behavior of a
> >>> hardware. As it is mentioned in the thermal.txt file.
> >>>
> >>>
> >>>>
> >>>> Thanks.
> >>>> Wei.
> >>>>
> >>>>>
> >>>>>>
> >>>>>> -Optional property:
> >>>>>> - coefficients: An array of integers (one signed cell) containing
> >>>>>> Type: array coefficients to compose a linear relation between
> >>>>>> Elem size: one cell the sensors listed in the thermal-sensors property.
> >>>>>> --
> >>>>>> 1.8.1.5
> >>>>>>
> >>>>
> >>> --
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> >>> More majordomo info at http://vger.kernel.org/majordomo-info.html
> >>>
> >>
>
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