linux-kernel - Re: [PATCH v7 06/13] coresight-tpdm: Add reset node to TPDM node

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Message-ID: <fc995a4a-81c5-648c-663a-4cee2cf15197@arm.com>
Date:   Mon, 7 Aug 2023 10:36:57 +0100
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, andersson@...nel.org
Subject: Re: [PATCH v7 06/13] coresight-tpdm: Add reset node to TPDM node

On 25/07/2023 08:15, 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       | 22 ++++++++++++++++++++++
>   2 files changed, 32 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
> index 4a58e64..dbc2fbd0 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	6.5


> +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.

Please fix this, we don't disable TPDM. If it only ever resets the 
datasets, please could we rename this as such ?

  i.e., reset_dataset or reset_dsb_data ?

> +
> +		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 52aa48a6..acc3eea 100644
> --- a/drivers/hwtracing/coresight/coresight-tpdm.c
> +++ b/drivers/hwtracing/coresight/coresight-tpdm.c
> @@ -159,6 +159,27 @@ 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)

Minor nit: alignment ? Could we have something like :

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);
> +
> +	return size;
> +}
> +static DEVICE_ATTR_WO(reset);
> +
>   /*
>    * value 1: 64 bits test data
>    * value 2: 32 bits test data
> @@ -199,6 +220,7 @@ 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,
>   };

Suzuki