Message-ID: <6320e079-4fc8-f435-52e5-6d5ad1369d84@quicinc.com>
Date:   Fri, 17 Mar 2023 14:18:35 +0800
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Subject: Re: [PATCH] coresight: core: Add sysfs node to reset all sources and
 sinks
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From:   Jinlong Mao <quic_jinlmao@quicinc.com>
To:     Mike Leach <mike.leach@linaro.org>,
        Suzuki K Poulose <suzuki.poulose@arm.com>
CC:     Mathieu Poirier <mathieu.poirier@linaro.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        <coresight@lists.linaro.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <linux-arm-msm@vger.kernel.org>,
        Tingwei Zhang <quic_tingweiz@quicinc.com>,
        Yuanfang Zhang <quic_yuanfang@quicinc.com>,
        Tao Zhang <quic_taozha@quicinc.com>,
        Hao Zhang <quic_hazha@quicinc.com>
References: <20230208111630.20132-1-quic_jinlmao@quicinc.com>
 <CAJ9a7ViBS9K6cKsOi3btw1b5cM9VTSb-q8s6W3WUAgeW3-T2Sg@mail.gmail.com>
 <CAJ9a7ViA5BsbLjRWMsttmpmcPh1yUXK8J79k-pqYybVZkMQHXQ@mail.gmail.com>
 <bb6c9df9-af9b-873e-85bd-a29d00bb39d7@arm.com>
 <1d9b8ee8-c3f2-99bc-cd4e-8c2dd0f04b2b@quicinc.com>
 <CAJ9a7Vh08A8b7YLF=pYPudB0CZ0XjEpF=4YHrNNd7xo_JQGYaA@mail.gmail.com>
 <0308d380-bc8b-cb66-55cd-b0934d8f9676@quicinc.com>
In-Reply-To: <0308d380-bc8b-cb66-55cd-b0934d8f9676@quicinc.com>
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On 3/1/2023 11:04 PM, Jinlong Mao wrote:
> Hi Mike & Suzuki,
>
> On 2/9/2023 10:56 PM, Mike Leach wrote:
>> Hi,
>>
>> On Thu, 9 Feb 2023 at 03:02, Jinlong Mao <quic_jinlmao@quicinc.com> 
>> wrote:
>>>
>>> On 2/9/2023 12:36 AM, Suzuki K Poulose wrote:
>>>> On 08/02/2023 16:20, Mike Leach wrote:
>>>>> Quick correction - you need to look for enable_source  / enable_sink
>>>>> files and disable those that are currently '1'
>>>>>
>>>>> Mike
>>>>>
>>>>> On Wed, 8 Feb 2023 at 16:16, Mike Leach <mike.leach@linaro.org> 
>>>>> wrote:
>>>>>> Hi
>>>>>>
>>>>>> As this is a sysfs only update - would it not be easier to simply 
>>>>>> use
>>>>>> a shell script to iterate through coresight/devices/ looking for
>>>>>> disable_source / disable_sink files and setting those accordingly?
>>>>>>
>>>>>> See tools/perf/tests/shell/test_arm_coresight.sh for an example of a
>>>>>> script that does similar iteration to test coresight in perf
>>>>>>
>>>> +1
>>>>
>>>> Suzuki
>>> Hi Mike & Suzuki,
>>>
>>> Sometimes user just want to have some quick test from PC with adb 
>>> commands.
>>> It is very easy to reset all sources and sinks' status by command 
>>> below.
>>> echo 1 > /sys/bus/coresight/reset_source_sink
>>>
>> Users of coresight via sysfs will have to know how to use the
>> coresight infrastructure in order to enable the sources and sinks in
>> the first place -
>> e.g
>> echo 1 > /sys/bus/coresight/devices/tmc_etr0/enable_sink
>> echo 1 > /sys/bus/coresight/devices/etm0/enable_source
>>
>> Given that they are aware of which sources and sinks they enabled -
>> disabling them should be simple.
>>
>>
>>> Preparing the script for test is not easy for users who are not 
>>> familiar
>>> with the coresight framework.
>>>
>> If there is a genuine use case were a user has opened so many sources
>> on the command line that they need a simpler way of closing them than
>> repeating the enabled commands with an
>> echo 0 > ...
>> then any script could be shipped as part of kernel/tools/coresight or
>> kernel/samples/coresight - they would not have to write it themselves,
>> and just run it from the command line - for example :-
>> ./kernel/tools/coresight/scripts/sysfs_disable_sources_and_sinks.sh
>>
>> Realistically users will only try out a couple of devices as the
>> usefulness of the sysfs interface is really limited to testing or
>> board bring up.
>> Any complex use with sysfs - as in the coresight tests I mentioned
>> earlier is really going to be done by scripting.
>>
>>
>> Regards
>>
>> Mike
>
> There is also requirement that reset all the sources and sinks in an 
> user space daemon.
> For such requirement, I think it is better to use only once sysfs node 
> instead of iterating through coresight/device folder in an user space 
> daemon.

Hi Mike & Suzuki,

In our internal build, there is binary executable which can configure 
coresight source/sink.
Before running the case, it will disable all the sources and sinks by 
writing reset_source_sink node to
avoid any other source packet's impact.


Thanks
Jinlong Mao

>
> Thanks
> Jinlong Mao
>
>>> Thanks
>>> Jinlong Mao
>>>
>>>>
>>
>>
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