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

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Date:   Tue, 28 Feb 2023 11:22:16 +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,
        Tao Zhang <taozha@....qualcomm.com>
Subject: Re: [PATCH v2 4/9] coresight-tpdm: Add reset node to TPDM node

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.

> +	tpdm_init_default_data(drvdata);

Could this be helper be renamed to

	tpdm_reset_dsb_data() ?

Because, that is what it does now.

> +
> +	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 ?

> +
> +	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.

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,
>   };