linux-kernel - Re: [PATCH v4 2/3] dt-bindings: arm: Add Coresight Dummy Trace

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Date:   Fri, 5 May 2023 20:05:29 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Suzuki K Poulose <suzuki.poulose@....com>
Cc:     Hao Zhang <quic_hazha@...cinc.com>,
        Mike Leach <mike.leach@...aro.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Konrad Dybcio <konradybcio@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Jonathan Corbet <corbet@....net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        Tingwei Zhang <quic_tingweiz@...cinc.com>,
        Jinlong Mao <quic_jinlmao@...cinc.com>,
        Yuanfang Zhang <quic_yuanfang@...cinc.com>,
        Tao Zhang <quic_taozha@...cinc.com>,
        Trilok Soni <quic_tsoni@...cinc.com>,
        linux-arm-msm@...r.kernel.org,
        Bjorn Andersson <andersson@...nel.org>,
        linux-doc@...r.kernel.org
Subject: Re: [PATCH v4 2/3] dt-bindings: arm: Add Coresight Dummy Trace

On Fri, May 05, 2023 at 11:54:03AM +0100, Suzuki Kuruppassery Poulose wrote:

[...]

> > +title: ARM Coresight Dummy component
> > +
> > +description: |
> > +  Coresight Dummy Trace Module is for the specific devices that kernel
> > +  don't have permission to access or configure, e.g., CoreSight TPDMs
> > +  on Qualcomm platforms. So there need driver to register dummy devices
> > +  as Coresight devices. It may also be used to define components that
> > +  may not have any programming interfaces (e.g, static links), so that
> > +  paths can be established in the driver. Provide Coresight API for
> > +  dummy device operations, such as enabling and disabling dummy devices.
> > +  Build the Coresight path for dummy sink or dummy source for debugging. > +
> > +  The primary use case of the coresight dummy is to build path in kernel
> > +  side for dummy sink and dummy source.
> > +
> > +maintainers:
> > +  - Mao Jinlong <quic_jinlmao@...cinc.com>
> > +  - Tao Zhang <quic_taozha@...cinc.com>
> > +  - Hao Zhang <quic_hazha@...cinc.com>
> > +  - Yuanfang Zhang <quic_yuanfang@...cinc.com>
> 
> Given this is a generic "CoreSight" component, I would prefer to have the
> CoreSight subsystem maintainers listed here (too). I don't mind
> the entries above, but would like to make sure that the subsystem
> people are aware of the changes happening here. Please use:
> 
> Mike Leach <mike.leach@...aro.org>
> Suzuki K Poulose <suzuki.poulose@....com>
> Leo Yan <leo.yan@...aro.org>

Given I am spending little time on CoreSight reviewing, I'd like to
use James Clark's email address to replace my own; I believe this
would benefit long term maintenance.

  James Clark <james.clark@....com>

Thanks!

> With the above:
> 
> Acked-by: Suzuki K Poulose <suzuki.poulose@....com>
> 
> > +
> > +properties:
> > +  compatible:
> > +    items:
> > +      - enum:
> > +          - arm,coresight-dummy-sink
> > +          - arm,coresight-dummy-source
> > +
> > +  out-ports:
> > +    $ref: /schemas/graph.yaml#/properties/ports
> > +
> > +    properties:
> > +      port:
> > +        description: Output connection from the source to Coresight
> > +          Trace bus.
> > +        $ref: /schemas/graph.yaml#/properties/port
> > +
> > +  in-ports:
> > +    $ref: /schemas/graph.yaml#/properties/ports
> > +
> > +    properties:
> > +      port:
> > +        description: Input connection from the Coresight Trace bus to
> > +          dummy sink, such as Embedded USB debugger(EUD).
> > +        $ref: /schemas/graph.yaml#/properties/port
> > +
> > +required:
> > +  - compatible
> > +
> > +if:
> > +  # If the compatible contains the below value
> > +  properties:
> > +    compatible:
> > +      contains:
> > +        const: arm,coresight-dummy-sink
> > +
> > +then:
> > +  required:
> > +    - in-ports
> > +
> > +else:
> > +  required:
> > +    - out-ports
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  # Minimum dummy sink definition. Dummy sink connect to coresight replicator.
> > +  - |
> > +    sink {
> > +      compatible = "arm,coresight-dummy-sink";
> > +
> > +      in-ports {
> > +        port {
> > +          eud_in_replicator_swao: endpoint {
> > +            remote-endpoint = <&replicator_swao_out_eud>;
> > +          };
> > +        };
> > +      };
> > +    };
> > +
> > +  # Minimum dummy source definition. Dummy source connect to coresight funnel.
> > +  - |
> > +    source {
> > +      compatible = "arm,coresight-dummy-source";
> > +
> > +      out-ports {
> > +        port {
> > +          dummy_riscv_out_funnel_swao: endpoint {
> > +            remote-endpoint = <&funnel_swao_in_dummy_riscv>;
> > +          };
> > +        };
> > +      };
> > +    };
> > +
> > +...
>