linux-kernel - Re: [PATCH v3 04/11] coresight-tpdm: Add reset node to TPDM node

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Message-ID: <4cde9235-e86a-73a0-5c6c-ac193328006b@arm.com>
Date:   Thu, 23 Mar 2023 14:48:04 +0000
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     Tao Zhang <quic_taozha@...cinc.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
Subject: Re: [PATCH v3 04/11] coresight-tpdm: Add reset node to TPDM node

On 23/03/2023 14:41, Suzuki K Poulose wrote:
> On 23/03/2023 06:04, 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.

Please justify why this "do everything" magic knob is required
when there are tunables for individual controls in the later
patches.

Suzuki

>>
>> Signed-off-by: Tao Zhang <quic_taozha@...cinc.com>
>> ---
>>   drivers/hwtracing/coresight/coresight-tpdm.c | 28 
>> ++++++++++++++++++++++++++++
>>   1 file changed, 28 insertions(+)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-tpdm.c 
>> b/drivers/hwtracing/coresight/coresight-tpdm.c
>> index 5e1e2ba..104638d 100644
>> --- a/drivers/hwtracing/coresight/coresight-tpdm.c
>> +++ b/drivers/hwtracing/coresight/coresight-tpdm.c
>> @@ -161,6 +161,33 @@ static void tpdm_datasets_setup(struct 
>> tpdm_drvdata *drvdata)
>>       drvdata->datasets |= pidr & GENMASK(TPDM_DATASETS - 1, 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);
>> +    /* Reset all datasets to ZERO, and init the default data*/
>> +    tpdm_init_datasets(drvdata);
> 
> With the suggested rename in the previous patch, you wouldn't need
> a comment here.
> 
>> +
>> +    spin_unlock(&drvdata->spinlock);
>> +
> 
> 
>> +    /* Disable tpdm if enabled */
>> +    if (drvdata->enable)
>> +        coresight_disable(drvdata->csdev);
> 
> Couldn't this be done via disable_source ? Please don't overload
> the sysfs handle.
> 
>> +
>> +    return size;
>> +}
>> +static DEVICE_ATTR_WO(reset);
> 
> Documentation for the sysfs node please ?
> 
> Suzuki
>