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Message-ID: <2d2e53f5-38fd-3636-9f91-a5e2de3833eb@quicinc.com>
Date:   Tue, 13 Sep 2022 15:56:45 +0800
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Subject: Re: [PATCH 1/9] dt-bindings: arm: Add support for DSB element
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To:     Rob Herring <robh@kernel.org>
CC:     Mathieu Poirier <mathieu.poirier@linaro.org>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Konrad Dybcio <konradybcio@gmail.com>,
        Mike Leach <mike.leach@linaro.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Jinlong Mao <quic_jinlmao@quicinc.com>,
        Leo Yan <leo.yan@linaro.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        <coresight@lists.linaro.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <devicetree@vger.kernel.org>,
        Tingwei Zhang <quic_tingweiz@quicinc.com>,
        Yuanfang Zhang <quic_yuanfang@quicinc.com>,
        Trilok Soni <quic_tsoni@quicinc.com>,
        Hao Zhang <quic_hazha@quicinc.com>,
        <linux-arm-msm@vger.kernel.org>, <bjorn.andersson@linaro.org>
References: <1662626705-13097-1-git-send-email-quic_taozha@quicinc.com>
 <1662626705-13097-2-git-send-email-quic_taozha@quicinc.com>
 <20220913004859.GA1948424-robh@kernel.org>
From:   Tao Zhang <quic_taozha@quicinc.com>
In-Reply-To: <20220913004859.GA1948424-robh@kernel.org>
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在 9/13/2022 8:48 AM, Rob Herring 写道:
> On Thu, Sep 08, 2022 at 04:44:57PM +0800, Tao Zhang wrote:
>> Add property "qcom,dsb-elem-size" to support DSB element for TPDA.
>> Specifies the DSB element size supported by each monitor connected
>> to the aggregator on each port. Should be specified in pairs (port,
>> dsb element size).
> What is DSB?

The full name of DSB is "Discrete Single Bit".

The DSB element size supported by different DSB subunit TPDMs is 
different, so TPDA needs to be informed through configuration in device 
tree.

>> Signed-off-by: Tao Zhang <quic_taozha@quicinc.com>
>> ---
>>   Documentation/devicetree/bindings/arm/qcom,coresight-tpda.yaml | 9 +++++++++
>>   1 file changed, 9 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/arm/qcom,coresight-tpda.yaml b/Documentation/devicetree/bindings/arm/qcom,coresight-tpda.yaml
>> index eb9bfc5..1bb3fdf 100644
>> --- a/Documentation/devicetree/bindings/arm/qcom,coresight-tpda.yaml
>> +++ b/Documentation/devicetree/bindings/arm/qcom,coresight-tpda.yaml
>> @@ -40,6 +40,13 @@ properties:
>>       minItems: 1
>>       maxItems: 2
>>   
>> +  qcom,dsb-elem-size:
>> +    description: |
>> +      Specifies the DSB element size supported by each monitor
>> +      connected to the aggregator on each port. Should be specified
>> +      in pairs (port, dsb element size).
>> +    $ref: /schemas/types.yaml#/definitions/uint32-array
> The binding (not yet upstream) says there is just 1 port (port 0). So
> why do you need more than a single uint32?
>
> Rob

TPDA(Trace, Profiling and Diagnostics Aggregator) is to provide 
packetization, funneling and timestamping of TPDM data.

Multiple monitors are connected to different input ports of TPDA.

  - - - -                 - - - -                 - - - -
| TPDM 0|      | TPDM 1 |     | TPDM 2|
  - - - -                 - - - -                 - - - -
     |                       |                       |
     |_ _ _ _ _ _     |         _ _ _ _  |
                         |   |        |
                         |   |        |
                       ------------------
                      |        TPDA      |
                       ------------------

There may be multiple DSB subunit TPDMs connected to different input 
ports of the same TPDA, so we need to use port here to define the 
distinction in device tree.


Best regards,

Tao