linux-kernel - Re: [PATCH v4 04/11] coresight-tpdm: Add reset node to TPDM node

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Message-ID: <597533f3-9920-1c48-423d-627812b2972d@quicinc.com>
Date:   Thu, 25 May 2023 16:36:14 +0800
From:   Tao Zhang <quic_taozha@...cinc.com>
To:     Suzuki K Poulose <suzuki.poulose@....com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Konrad Dybcio <konradybcio@...il.com>,
        Mike Leach <mike.leach@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
CC:     Jinlong Mao <quic_jinlmao@...cinc.com>,
        Leo Yan <leo.yan@...aro.org>,
        "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>,
        Yuanfang Zhang <quic_yuanfang@...cinc.com>,
        Trilok Soni <quic_tsoni@...cinc.com>,
        Hao Zhang <quic_hazha@...cinc.com>,
        <linux-arm-msm@...r.kernel.org>, <andersson@...nel.org>
Subject: Re: [PATCH v4 04/11] coresight-tpdm: Add reset node to TPDM node


On 5/23/2023 10:53 PM, Suzuki K Poulose wrote:
> On 27/04/2023 10:00, Tao Zhang wrote:
>> TPDM device need a node to reset the configurations and status of
>> it. This change provides a node to reset the configurations and
>> disable the TPDM if it has been enabled.
>>
>> Signed-off-by: Tao Zhang <quic_taozha@...cinc.com>
>> ---
>>   .../ABI/testing/sysfs-bus-coresight-devices-tpdm   | 10 ++++++++
>>   drivers/hwtracing/coresight/coresight-tpdm.c       | 27 
>> ++++++++++++++++++++++
>>   2 files changed, 37 insertions(+)
>>
>> diff --git 
>> a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm 
>> b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
>> index 4a58e64..686bdde 100644
>> --- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
>> +++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
>> @@ -11,3 +11,13 @@ Description:
>>           Accepts only one of the 2 values -  1 or 2.
>>           1 : Generate 64 bits data
>>           2 : Generate 32 bits data
>> +
>> +What:        /sys/bus/coresight/devices/<tpdm-name>/reset
>> +Date:        March 2023
>> +KernelVersion    6.3
>> +Contact:    Jinlong Mao (QUIC) <quic_jinlmao@...cinc.com>, Tao Zhang 
>> (QUIC) <quic_taozha@...cinc.com>
>> +Description:
>> +        (Write) Reset the dataset of the tpdm, and disable the tpdm.
>> +
>> +        Accepts only one value -  1.
>> +        1 : Reset the dataset of the tpdm
>> diff --git a/drivers/hwtracing/coresight/coresight-tpdm.c 
>> b/drivers/hwtracing/coresight/coresight-tpdm.c
>> index 6f8a8ab..2e64cfd 100644
>> --- a/drivers/hwtracing/coresight/coresight-tpdm.c
>> +++ b/drivers/hwtracing/coresight/coresight-tpdm.c
>> @@ -164,6 +164,32 @@ static int tpdm_datasets_setup(struct 
>> tpdm_drvdata *drvdata)
>>       return 0;
>>   }
>>   +static ssize_t reset_store(struct device *dev,
>> +                      struct device_attribute *attr,
>> +                      const char *buf,
>> +                      size_t size)
>> +{
>> +    int ret = 0;
>> +    unsigned long val;
>> +    struct tpdm_drvdata *drvdata = dev_get_drvdata(dev->parent);
>> +
>> +    ret = kstrtoul(buf, 10, &val);
>> +    if (ret || val != 1)
>> +        return -EINVAL;
>> +
>> +    spin_lock(&drvdata->spinlock);
>> +    tpdm_reset_datasets(drvdata);
>> +
>> +    spin_unlock(&drvdata->spinlock);
>> +
>> +    /* Disable tpdm if enabled */
>> +    if (drvdata->enable)
>> +        coresight_disable_source(drvdata->csdev, NULL);
>
> I am not really keen on doing this behind the back. What about the 
> path of components ? We could simply reject the request when the TPDA 
> is enabled and let the user alway follow :
>     1) Disable the TPDM manually via sysfs
>       2) Reset the TPDM.
>
> So, please remove the disable step here.

I will update this in the next patch series.

Best,

Tao

>
> Suzuki
>
>
>> +
>> +    return size;
>> +}
>> +static DEVICE_ATTR_WO(reset);
>> +
>>   /*
>>    * value 1: 64 bits test data
>>    * value 2: 32 bits test data
>> @@ -204,6 +230,7 @@ static ssize_t integration_test_store(struct 
>> device *dev,
>>   static DEVICE_ATTR_WO(integration_test);
>>     static struct attribute *tpdm_attrs[] = {
>> +    &dev_attr_reset.attr,
>>       &dev_attr_integration_test.attr,
>>       NULL,
>>   };
>