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Date: Fri, 5 Sep 2014 17:41:12 +0800
From: Wei Ni <wni@...dia.com>
To: Eduardo Valentin <edubezval@...il.com>
CC: Jean Delvare <jdelvare@...e.de>,
Guenter Roeck <linux@...ck-us.net>,
Stephen Warren <swarren@...dotorg.org>,
<lm-sensors@...sensors.org>,
"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 3/4] thermal: add more description for thermal-zones
Hi, Eduardo
On 09/01/2014 06:26 PM, Wei Ni wrote:
> On 08/29/2014 07:32 PM, edubezval@...il.com wrote:
>> Hello Wei,
>>
>> On Thu, Aug 28, 2014 at 11:03 PM, Wei Ni <wni@...dia.com> wrote:
>>> On 08/28/2014 09:21 PM, Eduardo Valentin wrote:
>>>> 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>;
>>>
>>>
>>> Yes, we have considered it, but in current kernel, it only supports 1
>>> sensor per zone. and according to the example (c), it's supposed to only
>>> support simple algorithm, such as:
>>> /* hotspot = 100 * bandgap - 120 * adc + 484 */
>>> coefficients = <100 -120 484>;
>>>
>>> but in our skin-temp driver, we will recored 20 history temperatures for
>>> every sensors, and set different coefficients for every history
>>> temperatures, our HW team have private mathematical mode to calculate
>>> these coeffs for different boards. And I think other users may use
>>> different algorithm to calculate thermal zone temperature based on
>>> several sensors.
>>>
>>> So I think it's better to register sensors to thermal zones, not set
>>> trips and binding cooling devices, then user's thermal driver can use
>>> them freely.
>>>
>>
>> In your system, the used governor is userspace, then?
>
> No, we developed a new governor named as "pid governor", it manages
> thermals based on output values of PID controller.
>
> Indeed, our thermal management includes skin-temp, soc-thermal,
> cpu-throttle driver and pid governor. This pach set is prepared for the
> skin-temp driver.
> As you know the tegra soc-therm is in upstreaming, and we will post
> other drivers step by step.
Will you take this patch, if so i will post skin-temp driver later.
Looking forward your comments :)
Thanks.
Wei.
>
> Thanks.
> Wei.
>
>>
>>> Thanks.
>>> Wei.
>>>
>>>>
>>>>
>>>>>
>>>>> 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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>>>>>>>>
>>>>>>>
>>>>>
>>>
>>
>>
>>
>
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