On Tue, 3 Jul 2018 at 03:44, Suzuki K Poulose [off-list ref]
wrote:

Hi Rob,

On 14/06/18 14:59, Rob Herring wrote:

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On Thu, Jun 14, 2018 at 2:53 AM, Suzuki K Poulose
[off-list ref] wrote:

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On 13/06/18 22:07, Matt Sealey wrote:

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-----Original Message-----
From: Mathieu Poirier <mathieu.poirier@linaro.org>

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So, if the suggestion is to use an existing property "unit", I am

fine

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with it, if people agree to it.

If we're going to have something sharply different than ACPI I prefer
Rob's idea.

No, the above comment is about using "unit" ( if it is a standard

property

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for specifying something specific to hardware) instead of

"coresight,hwid".

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I would prefer to stick to the DT graph bindings, because :

"unit" is not a standard property and I don't like it either.

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1) The connections are bi-directional => Well, not necessarily
bi-directional
in terms of the data flow. But the connection information is critical.

i.e,

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we need information about both the end-points of a connection, which

the DT

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graph bindings solves.

All we are missing is a way for specifying the "hardware port" number

and

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the
direction of flow. I don't see why do we need to create something new

just

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for
these two properties for something that exists today and works

reasonably

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well
for the usecase.

If you have "in-ports" and "out-ports" nodes, then that gives you
direction and you can use reg for the "hardware port".

in-ports {
   port@0 {
     reg = <0>;
     endpoint {...};
   };
   port@1 {
     reg = <1>;
     endpoint {...};
   };
};
out-ports {
   port@0 {
     reg = <0>;
     endpoint {...};
   };
};

I'll need to check, but dtc may need an update to not warn about this.

I did a quick check with the upstream dtc tool and the above form is
doesn't generate any errors.

Mathieu, Rob,

Shall I proceed with the proposal above ?

Yes - at the very least it will provide a new reference point to work form.

Thanks,
Mathieu

Suzuki