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    Subject[PATCH 07/20] coresight: dts: Document usage of graph bindings
    Date
    Before we update the bindings, document the current graph bindings
    and usage of additional properties.

    Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
    Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
    ---
    .../devicetree/bindings/arm/coresight.txt | 31 +++++++++++++++++++---
    1 file changed, 27 insertions(+), 4 deletions(-)

    diff --git a/Documentation/devicetree/bindings/arm/coresight.txt b/Documentation/devicetree/bindings/arm/coresight.txt
    index 9aa30a1..ed6b555 100644
    --- a/Documentation/devicetree/bindings/arm/coresight.txt
    +++ b/Documentation/devicetree/bindings/arm/coresight.txt
    @@ -52,9 +52,7 @@ its hardware characteristcs.
    clocks the core of that coresight component. The latter clock
    is optional.

    - * port or ports: The representation of the component's port
    - layout using the generic DT graph presentation found in
    - "bindings/graph.txt".
    + * port or ports: see "Graph bindings for Coresight" below.

    * Additional required properties for System Trace Macrocells (STM):
    * reg: along with the physical base address and length of the register
    @@ -71,7 +69,7 @@ its hardware characteristcs.
    AMBA markee):
    - "arm,coresight-replicator"

    - * port or ports: same as above.
    + * port or ports: see "Graph bindings for Coresight" below.

    * Optional properties for ETM/PTMs:

    @@ -90,6 +88,31 @@ its hardware characteristcs.
    * arm,scatter-gather: boolean. Indicates that the TMC-ETR can safely
    use the SG mode on this system.

    +Graph bindings for Coresight
    +-------------------------------
    +
    +Coresight components are interconnected to create a data path for the flow of
    +trace data generated from the "sources" to their collection points "sink".
    +Each coresight component must describe the "input" and "output" connections.
    +The connections must be described via generic DT graph bindings as described
    +by the "bindings/graph.txt", where each "port" along with an "endpoint"
    +component represents a hardware port and the connection.
    +
    +Since it is possible to have multiple connections for any coresight component
    +with a specific direction of data flow, each connection must define the
    +following properties to uniquely identify the connection details.
    +
    + * Direction of the data flow w.r.t the component :
    + Each input port must have the following property defined at the "endpoint"
    + for the port.
    + "slave-mode"
    +
    + * Hardware Port number at the component:
    + - The hardware port number is assumed to be the address of the "port"
    + component.
    +
    +
    +
    Example:

    1. Sinks
    --
    2.7.4
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