Re: [PATCHv9 02/20] thermal: introduce device tree parser

Eduardo Valentin
2014-01-06T14:55:55Z

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On 06-01-2014 09:51, Mark Rutland wrote:
> On Thu, Jan 02, 2014 at 05:50:06PM +0000, Matthew Longnecker wrote:
>>
>>> I think the platform driver may set governor for the thermal zone,
>>> so how about to add a property named as "governor",
>>> and parse it to tzp->governor_name,
>>> something like:
>>> ret = of_property_read_string(child, "governor", &str);
>>> if (ret == 0)
>>> if (strlen(str) < THERMAL_NAME_LENGTH)
>>> strcpy(tzp->governor_name, str);
>>>
>>> Thanks.
>>> Wei.
>>
>> DT is supposed to describe the hardware, right? The governor isn't
>> hardware -- it's a software control policy. On the other hand, that
>> control policy must be tuned according to the behaviors of the platform
>> hardware otherwise the system will be unstable.
>>
>> Is it appropriate to be naming the governor in DT? If so, is it equally
>> appropriate to describe any governor-specific parameters in DT (even
>> though they are pure software constructs)?
>
> The dt should be relatively static -- if the hardware doesn't change the
> dt shouldn't have to.
>
> The governers are not static. We can introduce new ones and throw away
> old ones at any time. Tuning parameters can also change at any time.
>
> I'd prefer to not have governer details described in the dt, and the
> choice of governer and configuration of its tuning parameters should be
> made at runtime somehow.

Agreed.

>
> Thanks,
> Mark.
>
>

--
You have got to be excited about what you are doing. (L. Lamport)

Eduardo Valentin

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