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

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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@xxxxxxxxxxx>
---
  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




[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [Linux for Sparc]     [IETF Annouce]     [Security]     [Bugtraq]     [Linux MIPS]     [ECOS]     [Asterisk Internet PBX]     [Linux API]

  Powered by Linux