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Message-ID: <a56a460e-7d50-fcf0-95a5-cf08eeb73f43@quicinc.com>
Date:   Mon, 27 Mar 2023 14:05:08 +0800
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Subject: Re: [PATCH v2 3/3] Documentation: trace: Add documentation for
 Coresight Dummy Trace
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To:     Suzuki K Poulose <suzuki.poulose@arm.com>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Konrad Dybcio <konradybcio@gmail.com>,
        Mike Leach <mike.leach@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Andy Gross <agross@kernel.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Jonathan Corbet <corbet@lwn.net>
CC:     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>,
        Jinlong Mao <quic_jinlmao@quicinc.com>,
        Yuanfang Zhang <quic_yuanfang@quicinc.com>,
        Tao Zhang <quic_taozha@quicinc.com>,
        Trilok Soni <quic_tsoni@quicinc.com>,
        <linux-arm-msm@vger.kernel.org>,
        Bjorn Andersson <andersson@kernel.org>,
        <linux-doc@vger.kernel.org>
References: <20230324061608.33609-1-quic_hazha@quicinc.com>
 <20230324061608.33609-4-quic_hazha@quicinc.com>
 <e383c17d-12b8-b134-acc5-82f515714562@arm.com>
From:   Hao Zhang <quic_hazha@quicinc.com>
In-Reply-To: <e383c17d-12b8-b134-acc5-82f515714562@arm.com>
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Hi Suzuki,

On 3/24/2023 7:00 PM, Suzuki K Poulose wrote:
> On 24/03/2023 06:16, Hao Zhang wrote:
>> Add documentation for Coresight Dummy Trace under trace/coresight.
>>
>> Signed-off-by: Hao Zhang <quic_hazha@quicinc.com>
>> ---
>>   .../trace/coresight/coresight-dummy.rst       | 58 +++++++++++++++++++
>>   1 file changed, 58 insertions(+)
>>   create mode 100644 Documentation/trace/coresight/coresight-dummy.rst
>>
>> diff --git a/Documentation/trace/coresight/coresight-dummy.rst 
>> b/Documentation/trace/coresight/coresight-dummy.rst
>> new file mode 100644
>> index 000000000000..819cabab8623
>> --- /dev/null
>> +++ b/Documentation/trace/coresight/coresight-dummy.rst
>> @@ -0,0 +1,58 @@
>> +.. SPDX-License-Identifier: GPL-2.0
>> +
>> +=============================
>> +Coresight Dummy Trace Module
>> +=============================
>> +
>> +    :Author:   Hao Zhang <quic_hazha@quicinc.com>
>> +    :Date:     March 2023
>> +
>> +Introduction
>> +---------------------------
>> +
>> +Coresight Dummy Trace Module is for the specific devices that HLOS don't
> 
> Please do not use cryptic abbreviations, please use "kernel"
> 
Sure, I will change it to "kernel".
> 
>> +have permission to access or configure. 
> 
> Such as Coresight sink EUD, some
>> +TPDMs etc. 
> Say "e.g., CoreSight TPDMs on Qualcomm platforms.:
> 
> So there need driver to register dummy devices as Coresight
>> +devices.
> 
> Add:
> 
> "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.
> 
I will take your advice in the next version of patch.
> 
> I think the following content may not be needed as they are part
> of the standard source/sink type devices, nothing specific to
> dummy devices.
> 
> --- vvvvv ---
>> +
>> +Sysfs files and directories
>> +---------------------------
>> +
>> +Root: ``/sys/bus/coresight/devices/dummy<N>``
>> +
>> +----
>> +
>> +:File:            ``enable_source`` (RW)
>> +:Notes:
>> +    - > 0 : enable the datasets of dummy source.
>> +
>> +    - = 0 : disable the datasets of dummy source.
>> +
>> +:Syntax:
>> +    ``echo 1 > enable_source``
>> +
>> +----
>> +
>> +:File:            ``enable_sink`` (RW)
>> +:Notes:
>> +    - > 0 : enable the datasets of dummy sink.
>> +
>> +    - = 0 : disable the datasets of dummy sink.
>> +
>> +:Syntax:
>> +    ``echo 1 > enable_sink``
>> +
>> +----
>> +
> 
> --- You may remove the above ^^^ ----
>
I will remove the above notes in the next version of patch.

Thanks,
Hao

>> +Config details
>> +---------------------------
>> +
>> +There are two types of nodes, dummy sink and dummy source. The nodes
>> +should be observed at the coresight path
>> +"/sys/bus/coresight/devices".
>> +e.g.
>> +/sys/bus/coresight/devices # ls -l | grep dummy
>> +dummy0 -> ../../../devices/platform/soc@0/soc@0:dummy_source/dummy0
>> +dummy1 -> ../../../devices/platform/soc@0/soc@0:dummy_sink/dummy1
> 
> Suzuki
>