diff mbox series

[4/9] coresight-tpdm: Add reset node to TPDM node

Message ID 1662626705-13097-5-git-send-email-quic_taozha@quicinc.com (mailing list archive)
State Superseded
Headers show
Series Add support to configure TPDM DSB subunit | expand

Commit Message

Tao Zhang Sept. 8, 2022, 8:45 a.m. UTC
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@quicinc.com>
---
 drivers/hwtracing/coresight/coresight-tpdm.c | 32 ++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

Comments

Suzuki K Poulose Oct. 24, 2022, 10:10 a.m. UTC | #1
On 08/09/2022 09:45, 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.

It is not clear to me *why* this is needed. Please could you
elaborate on the use case of this ? See my questions below.

> 
> Signed-off-by: Tao Zhang <quic_taozha@quicinc.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 69ea453..74cc653 100644
> --- a/drivers/hwtracing/coresight/coresight-tpdm.c
> +++ b/drivers/hwtracing/coresight/coresight-tpdm.c
> @@ -152,6 +152,37 @@ 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)

minor nit: Alignment

> +{
> +	int ret = 0;
> +	unsigned long val;
> +	struct tpdm_drvdata *drvdata = dev_get_drvdata(dev->parent);
> +
> +	ret = kstrtoul(buf, 10, &val);

So, any integer value written to the sysfs knob triggers the rest ?
It may be better to restrict this to "1".


> +	if (ret)
> +		return ret;
> +
> +	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 */
> +	tpdm_init_default_data(drvdata);

Why is this needed ? Does the DSB device configuration change
on the fly ?

> +
> +	spin_unlock(&drvdata->spinlock);
> +
> +	/* Disable tpdm if enabled */
> +	if (drvdata->enable)
> +		coresight_disable(drvdata->csdev);

Why is this needed ? Isn't this supposed to be triggered from the "path"
when the trace session is complete ?


Suzuki

> +
> +	return size;
> +}
> +static DEVICE_ATTR_WO(reset);
> +
>   /*
>    * value 1: 64 bits test data
>    * value 2: 32 bits test data
> @@ -192,6 +223,7 @@ 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,
>   };
Tao Zhang Oct. 27, 2022, 6:52 a.m. UTC | #2
Hi Suzuki,

在 10/24/2022 6:10 PM, Suzuki K Poulose 写道:
> On 08/09/2022 09:45, 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.
>
> It is not clear to me *why* this is needed. Please could you
> elaborate on the use case of this ? See my questions below.
For example, we usually reset the configuration through the "reset"
node before using a TPDM, so as to avoid the previous configuration
affecting the current use. And in some scenarios, it may be necessary
to reset the TPDM configuration to complete the verification of certain
function.
>>
>> Signed-off-by: Tao Zhang <quic_taozha@quicinc.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 69ea453..74cc653 100644
>> --- a/drivers/hwtracing/coresight/coresight-tpdm.c
>> +++ b/drivers/hwtracing/coresight/coresight-tpdm.c
>> @@ -152,6 +152,37 @@ 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)
>
> minor nit: Alignment
>
I will update this in the next patch series.
>> +{
>> +    int ret = 0;
>> +    unsigned long val;
>> +    struct tpdm_drvdata *drvdata = dev_get_drvdata(dev->parent);
>> +
>> +    ret = kstrtoul(buf, 10, &val);
>
> So, any integer value written to the sysfs knob triggers the rest ?
> It may be better to restrict this to "1".
>
Make sense, I will update this in the next patch series.
>
>> +    if (ret)
>> +        return ret;
>> +
>> +    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 */
>> +    tpdm_init_default_data(drvdata);
>
> Why is this needed ? Does the DSB device configuration change
> on the fly ?
>
We usually reset the configuration through the "reset" node at the
beginning of using a TPDM. DSB related elements need to be initialized
before configuring them.
The TPDM is usually to be used by the following sequence.
Reset(initialization) -> Configure -> Enable to use
>> +
>> +    spin_unlock(&drvdata->spinlock);
>> +
>> +    /* Disable tpdm if enabled */
>> +    if (drvdata->enable)
>> +        coresight_disable(drvdata->csdev);
>
> Why is this needed ? Isn't this supposed to be triggered from the "path"
> when the trace session is complete ?
>
In some scenarios, it may be necessary to reset the TPDM configuration
in the process of verification and re-configure the TPDM. If this is the
case, we need to disable the TPDM first, and re-configure before enabling
it again.
>
> Suzuki
>
>> +
>> +    return size;
>> +}
>> +static DEVICE_ATTR_WO(reset);
>> +
>>   /*
>>    * value 1: 64 bits test data
>>    * value 2: 32 bits test data
>> @@ -192,6 +223,7 @@ 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 Regards
Tao
diff mbox series

Patch

diff --git a/drivers/hwtracing/coresight/coresight-tpdm.c b/drivers/hwtracing/coresight/coresight-tpdm.c
index 69ea453..74cc653 100644
--- a/drivers/hwtracing/coresight/coresight-tpdm.c
+++ b/drivers/hwtracing/coresight/coresight-tpdm.c
@@ -152,6 +152,37 @@  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, 10, &val);
+	if (ret)
+		return ret;
+
+	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 */
+	tpdm_init_default_data(drvdata);
+
+	spin_unlock(&drvdata->spinlock);
+
+	/* Disable tpdm if enabled */
+	if (drvdata->enable)
+		coresight_disable(drvdata->csdev);
+
+	return size;
+}
+static DEVICE_ATTR_WO(reset);
+
 /*
  * value 1: 64 bits test data
  * value 2: 32 bits test data
@@ -192,6 +223,7 @@  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,
 };