Re: [Query] thermal: Who is using "cooling-{min|max}-level}" properties ?

[Daniel Lezcano <daniel.lezcano@linaro.org>]

On 12/02/2018 07:10, Viresh Kumar wrote:
> On 09-02-18, 13:14, Daniel Lezcano wrote:
>> Right. The semantic is unclear. The expected cooling-cells value is
>> always 2 (the code ignore values greater than two and yell if it is less
>> than 2). And the cooling-device binding tells there are two states.
> 
> They are fixed to 2 as we don't need to use it differently for now.
> But that's more about how Linux is using this stuff. The binding still
> needs to provide a way to have more cells than just 2.
> 
>> So the question is why do we need a cooling-cells as the information is
>> pointless here (always 2) ?
> 
> To show that the device is a "cooling-device" and I see that
> consistent with everything else in DT, for example: interrupt-cells,
> gpio-cells, clock-cells, reset-cells, dma-cells. The "*-cells"
> properties is used widely to tell what the device can behave as, i.e.
> a cooling-device in our case.

Ah, yes. That's right.

Well I don't know. If that is the way the other drivers are doing, I
suppose we should keep it as it is.

> Now we always use 2 parameters exactly is a different thing all
> together :)
> 
>> I see this field is artificially used to tell the cpufreq driver "please
>> register me as a cooling device". This is inconsistent from my pov.
> 
> But that's how its used for every other controller, what's different
> here ?
> 
>> Furthermore, the thermal-zone with the cooling device binds with the CPU
>> phandle, not the cooling-cells.
> 
> Yeah, because that's the device really.
> 
>> Putting apart the device binding changes discussion for the moment. Why
>> not register the cpufreq driver in all the cases and then drop
> 
> s/cpufreq driver/cpufreq cooling driver/ ??

yes.

>> cooling-cells ? So when the opps are present, its registers in the
>> cpufreq->ready callback.
> 
> How will someone tell if they don't need the cooling infrastructure ?
> Specially for multiplatform thing.

They don't define a cooling device in the DT ?


-- 
 <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs

Follow Linaro:  <http://www.facebook.com/pages/Linaro> Facebook |
<http://twitter.com/#!/linaroorg> Twitter |
<http://www.linaro.org/linaro-blog/> Blog