linux-kernel - Re: [PATCH v2 4/9] coresight-tpdm: Add reset node to TPDM node

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Message-ID: <75b61bc3-fb68-cd6e-8849-055e785ceb72@quicinc.com>
Date:   Wed, 1 Mar 2023 14:35:49 +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>, <bjorn.andersson@...aro.org>,
        Tao Zhang <taozha@....qualcomm.com>
Subject: Re: [PATCH v2 4/9] coresight-tpdm: Add reset node to TPDM node


在 2/28/2023 7:22 PM, Suzuki K Poulose 写道:
> On 19/01/2023 07:41, Tao Zhang wrote:
>> TPDM device need a node to reset the configurations and status of
>> it. So as to avoid the previous configurations affecting the
>> current use, the configurations need to be reset first. And in
>> some scenarios, it may be necessary to reset the TPDM
>> configurations to complete the verification of certain function.
>> 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>
>> Signed-off-by: Tao Zhang <taozha@....qualcomm.com>
>> ---
>>   drivers/hwtracing/coresight/coresight-tpdm.c | 32 
>> ++++++++++++++++++++++++++++
>>   1 file changed, 32 insertions(+)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-tpdm.c 
>> b/drivers/hwtracing/coresight/coresight-tpdm.c
>> index 6befc87..c29d667d 100644
>> --- a/drivers/hwtracing/coresight/coresight-tpdm.c
>> +++ b/drivers/hwtracing/coresight/coresight-tpdm.c
>> @@ -161,6 +161,37 @@ static void tpdm_init_default_data(struct 
>> tpdm_drvdata *drvdata)
>>       }
>>   }
>>   +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, 0, &val);
>> +    if (ret || (val != 1))
>> +        return -EINVAL;
>> +
>> +    spin_lock(&drvdata->spinlock);
>> +    /* Reset all datasets to ZERO */
>> +    if (drvdata->dsb != NULL)
>> +        memset(drvdata->dsb, 0, sizeof(struct dsb_dataset));
>> +
>> +    /* Init the default data */
>
> Code is self explanatory, don't need a comment here.
OK, got it.
>
>> +    tpdm_init_default_data(drvdata);
>
> Could this be helper be renamed to
>
>     tpdm_reset_dsb_data() ?
>
> Because, that is what it does now.

Sure, I will change its name as "tpdm_reset_data()" since DSB is only 
one of the data type which TPDM supports.

>
>> +
>> +    spin_unlock(&drvdata->spinlock);
>> +
>> +    /* Disable tpdm if enabled */
>> +    if (drvdata->enable)
>> +        coresight_disable(drvdata->csdev);
>
> Woh, where did that come from ? Don't you have a disable handle ?

The function "coresight_disable" is defined in the file "coresight-core.c".

This is a generic disablement handle.

>
>> +
>> +    return size;
>> +}
>> +static DEVICE_ATTR_WO(reset);
>> +
>
> This looks a bit pointless to me, given we have separate controls for 
> all that is being achieved above.

I will move the function of resetting all datasets to zero to 
"tpdm_disable".

Thanks for your advice.

>
> Suzuki
>
>>   /*
>>    * value 1: 64 bits test data
>>    * value 2: 32 bits test data
>> @@ -201,6 +232,7 @@ 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,
>>   };
>
Best,

Tao