Date:   Wed, 24 Oct 2018 10:29:08 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Andy Tang <andy.tang@....com>,
        "rui.zhang@...el.com" <rui.zhang@...el.com>
Cc:     "edubezval@...il.com" <edubezval@...il.com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH] thermal: qoriq: add multiple sensors support

On 24/10/2018 04:48, Andy Tang wrote:
> Hi Daniel,
> 
>> -----Original Message-----
>> From: Daniel Lezcano <daniel.lezcano@...aro.org>
>> Sent: 2018年10月16日 19:21
>> To: Andy Tang <andy.tang@....com>; rui.zhang@...el.com
>> Cc: edubezval@...il.com; linux-pm@...r.kernel.org;
>> linux-kernel@...r.kernel.org; Rob Herring <robh+dt@...nel.org>
>> Subject: Re: [PATCH] thermal: qoriq: add multiple sensors support
>>
>>>>>> The current code is reading the DT in order to get the sensor id
>>>>>> and initialize it. IOW, the DT gives the sensors to use.
>>>>>>
>>>>>> IMO, it would be more self contained if the driver initializes all
>>>>>> the sensors without taking care of the DT and let the of- code to
>>>>>> do the binding when the thermal zone, no ?
>>>>> [Andy] could you please explain more about this way? I am not sure
>>>>> how
>>>> to implement it.
>>>>> But one thing is for sure: we must get the sensor IDs explicitly so
>>>>> that we can enable them by the following command:
>> tmu_write(qdata,
>>>>> sites | TMR_ME | TMR_ALPF, &qdata->regs->tmr);
>>>>
>>>> What I meant is about code separation between the driver itself and
>>>> the of-thermal code.
>>>>
>>>> The code above re-inspect the DT to find out the sensor ids in order
>>>> to enable them and somehow this is not wrong but breaks the self
>>>> encapsulation of the driver. I was suggesting if it isn't possible to
>>>> enable all the sensors without taking care of digging into the DT.
>>>
>>> [Andy] I don't want to re-parse the DT here too. But I have to.
>>> This driver will be used by all our SOCs with different sensor IDs and
>> number.
>>> For example: there are 2 sensors on ls1088a platform with ID 0 and 1.
>>> While on ls1043a there are 6 sensors with ID 0, 1, 2, 3, 4, 5.
>>> If we don't scan the DT we would not know how many sensors it is and
>>> what are the sensor's IDs, unless we hardcode it in driver.
>>
>> Yes, you are not the only one in this situation IMO and the drivers
>> supporting multiple sensors are increasing, so this will repeat again and
>> again.
>>
>> That could be hardcoded in the driver by using the compatible string but it
>> will be nicer if we can fix that in the DT.
>>
>> [Cc'ing Rob]
>>
>> What is missing is a description of the sensors id in the temperature
>> device node. We have the <thermal-sensor-cells> with 0 or 1 telling if
>> there is one or several sensors but we can't specify which sensor ids we
>> have. The only alternative is to parse the thermal zones to found out which
>> sensors are in use and use them to initialize the driver, an approach which
>> breaks the self-encapsulation: the of-thermal framework is the one in
>> charge of doing the link between the thermal zone and a sensor id.
>>
>> Is it acceptable to add the list of the sensors id in the temp device node, so
>> the driver can initialize these sensors without parsing the thermal zone in
>> the DT ?
>>
> Have you got any conclusion yet?
> When can I send the next version of this patch?


Let's give an opportunity to Rob to answer.


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