On 12/02/2018 07:10, Viresh Kumar wrote:

On 09-02-18, 13:14, Daniel Lezcano wrote:

quoted

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.

quoted

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 :)

quoted

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 ?

quoted

Furthermore, the thermal-zone with the cooling device binds with the CPU
phandle, not the cooling-cells.

Yeah, because that's the device really.

quoted

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.

quoted

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 ?


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