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