On Thu, Jun 14, 2018 at 2:53 AM, Suzuki K Poulose Suzuki.Poulose@arm.com wrote:
On 13/06/18 22:07, Matt Sealey wrote:
-----Original Message----- From: Mathieu Poirier mathieu.poirier@linaro.org
So, if the suggestion is to use an existing property "unit", I am fine 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 for specifying something specific to hardware) instead of "coresight,hwid". I would prefer to stick to the DT graph bindings, because :
"unit" is not a standard property and I don't like it either.
- The connections are bi-directional => Well, not necessarily
bi-directional in terms of the data flow. But the connection information is critical. i.e, we need information about both the end-points of a connection, which the DT graph bindings solves.
All we are missing is a way for specifying the "hardware port" number and the direction of flow. I don't see why do we need to create something new just for these two properties for something that exists today and works reasonably 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.
What are you trying to say about being sharply different than ACPI?
The proposed Coresight ACPI draft bindings are based on the ACPI Graph bindings (just like the DT graph bindings and is compatible with it, in terms of the APIs. i.e, fwnode_graph_* operations work for both ACPI and DT alike).
So, what Mathieu, in turn means is, if we depart from the DT Graph bindings, which I personally don't see any benefit in.
If DT bindings can be reused for ACPI, that's fine, but don't expect any DT bindings to be accepted simply because they match ACPI bindings.
Rob