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SubjectRe: [RFC PATCH 6/8] dts: coresight: Clean up the device tree graph bindings
On Fri, Jun 01, 2018 at 02:16:05PM +0100, Suzuki K Poulose wrote:
> The coresight drivers relied on default bindings for graph
> in DT, while reusing the "reg" field of the "ports" to indicate
> the actual hardware port number for the connections. However,
> with the rules getting stricter w.r.t to the address mismatch
> with the label, it is no longer possible to use the port address
> field for the hardware port number. Hence, we add an explicit
> property to denote the hardware port number, "coresight,hwid"
> which must be specified for each "endpoint".
>
> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> Cc: Sudeep Holla <sudeep.holla@arm.com>
> Cc: Rob Herring <robh@kernel.org>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> ---
> .../devicetree/bindings/arm/coresight.txt | 26 +++++++++---
> drivers/hwtracing/coresight/of_coresight.c | 46 ++++++++++++++++------
> 2 files changed, 54 insertions(+), 18 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/arm/coresight.txt b/Documentation/devicetree/bindings/arm/coresight.txt
> index bd36e40..385581a 100644
> --- a/Documentation/devicetree/bindings/arm/coresight.txt
> +++ b/Documentation/devicetree/bindings/arm/coresight.txt
> @@ -104,7 +104,11 @@ properties to uniquely identify the connection details.
> "slave-mode"
>
> * Hardware Port number at the component:
> - - The hardware port number is assumed to be the address of the "port" component.
> + - (Obsolete) The hardware port number is assumed to be the address of the "port" component.
> + - Each "endpoint" must define the hardware port of the local end of the
> + connection using the following property:
> + "coresight,hwid" - 32bit integer, hardware port number at the local end.

"coresight" is not a vendor and properties are in the form
[<vendor>,]<prop-name>.

> +
>
>
> Example:
> @@ -120,6 +124,7 @@ Example:
> etb_in_port: endpoint@0 {

There shouldn't be a unit address here because there is no reg property.

> slave-mode;
> remote-endpoint = <&replicator_out_port0>;
> + coresight,hwid = <0>;

It doesn't make sense for these to be in the endpoint. If you had
multiple endpoints, then you would have to duplicate it. "ports" are
a single data stream. "endpoints" are connections to that stream. So if
you have a muxed (input) or fanout/1-to-many (output) connection, then
you have multiple endpoints.

The same applied to the slave-mode property, but that ship has sailed.
No reason to continue that though.

> };
> };
> };
> @@ -134,6 +139,7 @@ Example:
> tpiu_in_port: endpoint@0 {
> slave-mode;
> remote-endpoint = <&replicator_out_port1>;
> + coresight,hwid = <0>;
> };
> };
> };
> @@ -154,6 +160,7 @@ Example:
> reg = <0>;
> replicator_out_port0: endpoint {
> remote-endpoint = <&etb_in_port>;
> + coresight,hwid = <0>;
> };
> };
>
> @@ -161,15 +168,17 @@ Example:
> reg = <1>;
> replicator_out_port1: endpoint {
> remote-endpoint = <&tpiu_in_port>;
> + coresight,hwid = <1>;
> };
> };
>
> /* replicator input port */
> port@2 {
> - reg = <0>;
> + reg = <1>;

This will still get flagged as an error. reg must be 2 here.

Rob

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