linux-kernel - Re: [PATCH v3 3/3] Documentation: trace: Add documentation for Coresight Dummy Trace

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Message-ID: <82aab1d7-0157-983a-5f92-3dcd1e04fe23@quicinc.com>
Date:   Fri, 12 May 2023 15:51:34 +0800
From:   Hao Zhang <quic_hazha@...cinc.com>
To:     Bagas Sanjaya <bagasdotme@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        Leo Yan <leo.yan@...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>
CC:     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 v3 3/3] Documentation: trace: Add documentation for
 Coresight Dummy Trace

Hi Bagas,

On 5/10/2023 12:29 PM, Bagas Sanjaya wrote:
> On Sat, Apr 22, 2023 at 03:37:14PM +0800, Hao Zhang wrote:
>> +Introduction
>> +---------------------------
>> +
>> +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.
>> +
>> +Config details
>> +---------------------------
>> +
>> +There are two types of nodes, dummy sink and dummy source. The nodes
>> +should be observed at the below coresight path::
>> +
>> +    ``/sys/bus/coresight/devices``.
>> +
>> +e.g.::
>> +
>> +    / $ ls -l /sys/bus/coresight/devices | grep dummy
>> +    dummy0 -> ../../../devices/platform/soc@...oc@0:dummy_source/dummy0
>> +    dummy1 -> ../../../devices/platform/soc@...oc@0:dummy_sink/dummy1
> 
> The wording confuses me, so I have to make the improv:
> 
> ---- >8 ----
> diff --git a/Documentation/trace/coresight/coresight-dummy.rst b/Documentation/trace/coresight/coresight-dummy.rst
> index 7cb59f080c8892..f0a92669288b0c 100644
> --- a/Documentation/trace/coresight/coresight-dummy.rst
> +++ b/Documentation/trace/coresight/coresight-dummy.rst
> @@ -8,27 +8,25 @@ Coresight Dummy Trace Module
>       :Date:     May 2023
>   
>   Introduction
> ----------------------------
> +------------
>   
> -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 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. For these devices, a dummy driver is needed to register them as
> +Coresight devices. The module may also be used to define components that may
> +not have any programming interfaces (e.g, static links), so that paths can be
> +created in the driver. It provides Coresight API for operations on dummy
> +devices, such as enabling and disabling them. It also provides the Coresight
> +dummy sink/source paths for debugging.
>   
>   Config details
> ----------------------------
> +--------------
>   
> -There are two types of nodes, dummy sink and dummy source. The nodes
> -should be observed at the below coresight path::
> +There are two types of nodes, dummy sink and dummy source. These nodes
> +are available at ``/sys/bus/coresight/devices``.
>   
> -    ``/sys/bus/coresight/devices``.
> +Example output::
>   
> -e.g.::
> -
> -    / $ ls -l /sys/bus/coresight/devices | grep dummy
> +    $ ls -l /sys/bus/coresight/devices | grep dummy
>       dummy_sink0 -> ../../../devices/platform/soc@...oc@0:sink/dummy_sink0
>       dummy_source0 -> ../../../devices/platform/soc@...oc@0:source/dummy_source0
> 
> Thanks.
> 

Thanks for your review and comments, will update it in the next patch 
series.

Thanks,
Hao