linux-kernel - Re: [PATCH v4 1/3] dt-bindings: Document the hi3660 thermal sensor bindings

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Date:   Mon, 4 Sep 2017 12:36:25 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     "Wangtao (Kevin, Kirin)" <kevin.wangtao@...ilicon.com>,
        rui.zhang@...el.com, edubezval@...il.com, robh+dt@...nel.org,
        mark.rutland@....com, xuwei5@...ilicon.com,
        catalin.marinas@....com, will.deacon@....com
Cc:     leo.yan@...aro.org, kevin.wangtao@...aro.org,
        linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        sunzhaosheng@...ilicon.com, gengyanping@...ilicon.com
Subject: Re: [PATCH v4 1/3] dt-bindings: Document the hi3660 thermal sensor
 bindings

On 04/09/2017 08:39, Wangtao (Kevin, Kirin) wrote:
> 
> 
> 在 2017/9/1 2:24, Daniel Lezcano 写道:
>> On 29/08/2017 10:17, Tao Wang wrote:
>>> From: Tao Wang <kevin.wangtao@...aro.org>
>>>
>>> This adds documentation of device tree bindings for the
>>> thermal sensor controller of hi3660 SoC.
>>>
>>> Signed-off-by: Tao Wang <kevin.wangtao@...aro.org>
>>> ---
>>>   .../devicetree/bindings/thermal/hisi-tsensor.txt   | 37
>>> ++++++++++++++++++++++
>>>   1 file changed, 37 insertions(+)
>>>   create mode 100644
>>> Documentation/devicetree/bindings/thermal/hisi-tsensor.txt
>>>
>>> diff --git
>>> a/Documentation/devicetree/bindings/thermal/hisi-tsensor.txt
>>> b/Documentation/devicetree/bindings/thermal/hisi-tsensor.txt
>>> new file mode 100644
>>> index 0000000..4643dbe
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/thermal/hisi-tsensor.txt
>>> @@ -0,0 +1,37 @@
>>> +* Temperature Sensor on hisilicon SoC
>>> +
>>> +Hisilicon SoC supplies temperature sensor feature, each CPU cluster
>>> and G3D
>>> +area contains a temperture sensor. The temperture sensor produces an
>>> output
>>> +value which has a linear relationship with the temperture of the area.
>>> +
>>
>> s/temperture/temperature/
> THX
>>
>>> +for Hi3660,
>>> +sensor0 monitors the temperture of A53;
>>> +sensor1 monitors the temperture of A72;
>>> +sensor2 monitors the temperture of GPU;
>>> +sensor3 is a virtual sensor, which produces the maximum value of all
>>> sensors;
>>> +sensor4 is a virtual sensor, which produces the average value of all
>>> sensors.
>>
>> I don't think we need to escribe the virtual sensors in the DT bindings.
> I just want to let user know the sensor id of virtual sensor, I also
> define it in header file, so the header file is enough?

The virtual sensor (or something else) should be a separate, generic
thing to be used for anyone.

>>> +** Required properties :
>>> +- compatible: "hisilicon,thermal-tsensor".
>>> +- reg: physical reg address of thermal sensor and length of memory
>>> mapped
>>> +  region.
>>> +- hisi,tsensors: number of hardware tsensors
>>> +- hisi,coef:    An array of integers (one signed cell) containing
>>> +        coefficients to turn adc value to temperture.
>>> +- hisi,adc-range: adc value range, minimum value is followed by
>>> maximum value.
>>> +- #thermal-sensor-cells: Should be 1. See ./thermal.txt for a
>>> description.
>>> +
>>> +Example :
>>> +Hi3660:
>>> +tsensor: tsensor@...30000 {
>>> +    compatible = "hisilicon,hi3660-tsensor";
>>> +    #address-cells = <2>;
>>> +    #size-cells = <2>;
>>> +    reg = <0x0 0xfff3001c 0x0 0x4>,
>>> +        <0x0 0xfff3005c 0x0 0x4>,
>>> +        <0x0 0xfff3009c 0x0 0x4>;
>>> +    hisi,tsensors = <HISI_MAX_TSENSORS>;
>>> +    hisi,coef = <165000 (-40000)>;
>>> +    hisi,adc-range = <0x74 0x39A>;
>>
>> Do we really need max sensors, coef and adc range to be specified in
>> the DT?
>>
>> Can't we assume the hi3660-tsensor has 3 sensors, and hard-code the
>> coef, adc, in the driver itself?
> My purpose is to make the driver be compitable with our future platform.

I don't see the point. The compatibility could be handled in the driver
itself, no?


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