Re: [PATCH v6 2/2] arm64: dts: sdm845: Add gpu and gmu device nodes

[Rajendra Nayak <rnayak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>]

On 12/21/2018 2:59 AM, Stephen Boyd wrote:
> Quoting Rob Herring (2018-12-19 15:47:25)
>> On Wed, Dec 19, 2018 at 4:40 PM Doug Anderson <dianders@chromium.org> wrote:
>>> On Wed, Dec 19, 2018 at 12:40 PM Doug Anderson <dianders@chromium.org> wrote:
>>>> On Wed, Dec 19, 2018 at 12:09 PM Rob Herring <robh@kernel.org> wrote:
>>>> ...but it does have a frequency, doesn't it?
>>>>
>>>> +   compatible = "operating-points-v2-qcom-level";
>>>> +
>>>> +   opp-710000000 {
>>>> +     opp-hz = /bits/ 64 <710000000>;
>>>> +     qcom,level = <RPMH_REGULATOR_LEVEL_TURBO_L1>;
>>>> +   };
>>>
>>> Ah, I perhaps see the confusion.  So Rajendra's usage of
>>> "operating-points-v2-qcom-level" [1] doesn't have a frequency but
>>> Jordan's do.  So I guess it makes sense that Jordan's have the
>>> fallback compatible but Rajendra's don't?
>>
>> Is having it useful to s/w that doesn't understand
>> "operating-points-v2-qcom-level"? If so, then add
>> "operating-points-v2". If not, then don't.
> 
> The only benefit I see in having "operating-points-v2" is that we don't
> need to update the of_skipped_node_table[] in drivers/platform/of.c to
> have all the variants of operating-points-v2-* when they decide to not
> use anything from the "base" binding.
> 
> If that fails to work because opp-hz is required for the
> "operating-points-v2" binding but sometimes
> operating-points-v2-qcom-level doesn't require it I guess we need to
> update the skip table or make some generic property like
> 'this-is-not-a-device' that these various data tables in DT can be
> marked with so we don't make platform devices for them.
> 
> Regardless of the above, we should update the binding for
> operating-points-v2-qcom-level to say that opp-hz isn't always required
> when the qcom-level compatible is present. It looks like it just says
> that it builds on top of the opp binding so that's not obvious.

Sure, I can respin with those details added in.
So I am guessing the conclusion is to use a fallback "operating-points-v2"
compatible *only* when we do have opp-hz along with qcom,level (as in the
case with gpu) and not have a fallback compatible in cases when we don't
have opp-hz (as in the case of rpm power domains)?
That seems a little inconsistent, and given Rob said either way is fine,
just do one way or the other and not both, I am inclined to think we should
just have a "operating-points-v2-qcom-level" and no fallback compatible.
Does that make sense?

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