Re: [PATCH v3 3/4] thermal: add more description for thermal-zones

[Eduardo Valentin <edubezval@gmail.com>]

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@nvidia.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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> >>>
> >>
>