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

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Message-ID: <53FD484F.7030504@nvidia.com>
Date:	Wed, 27 Aug 2014 10:54:07 +0800
From:	Wei Ni <wni@...dia.com>
To:	Eduardo Valentin <edubezval@...il.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

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.

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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