linux-kernel - Re: [PATCH v2 09/10] coresight: Cleanup coresight DT bindings

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Message-ID: <20180725160939.GA24323@rob-hp-laptop>
Date:   Wed, 25 Jul 2018 10:09:39 -0600
From:   Rob Herring <robh@...nel.org>
To:     Suzuki K Poulose <suzuki.poulose@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        mathieu.poirier@...aro.org, sudeep.holla@....com,
        frowand.list@...il.com, devicetree@...r.kernel.org,
        mark.rutland@....com, matt.sealey@....com,
        charles.garcia-tobin@....com, coresight@...ts.linaro.org,
        john.horley@....com, mike.leach@...aro.org
Subject: Re: [PATCH v2 09/10] coresight: Cleanup coresight DT bindings

On Thu, Jul 19, 2018 at 11:55:13AM +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. This can
> cause duplicate ports with same addresses, but different
> direction. 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.
> 
> This patch introduces new DT binding rules for coresight
> components, based on the same generic DT graph bindings, but
> avoiding the address duplication.
> 
> - All output ports must be specified under a child node with
>   name "out-ports".
> - All input ports must be specified under a childe node with
>   name "in-ports".
> - Port address should match the hardware port number.
> 
> The support for legacy bindings is retained, with a warning.
> 
> Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
> Cc: Sudeep Holla <sudeep.holla@....com>
> Cc: Rob Herring <robh@...nel.org>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
> ---
>  .../devicetree/bindings/arm/coresight.txt          | 91 ++++++++++----------
>  drivers/hwtracing/coresight/of_coresight.c         | 97 +++++++++++++++++++---
>  2 files changed, 129 insertions(+), 59 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/arm/coresight.txt b/Documentation/devicetree/bindings/arm/coresight.txt
> index 8e21512..f39d2c6 100644
> --- a/Documentation/devicetree/bindings/arm/coresight.txt
> +++ b/Documentation/devicetree/bindings/arm/coresight.txt
> @@ -104,19 +104,9 @@ 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.
> -

Why do you add this in the previous patch and then remove it here?

> + * All output ports must be listed inside a child node named "out-ports"
> + * All input ports must be listed inside a child node named "in-ports".
> + * Port address must match the hardware port number.