Re: [PATCH v3 02/11] coresight-tpda: Add DSB dataset support

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On 23/03/2023 06:03, Tao Zhang wrote:
Read the DSB element size from the device tree. Set the register
bit that controls the DSB element size of the corresponding port.

Signed-off-by: Tao Zhang <quic_taozha@xxxxxxxxxxx>
---
  drivers/hwtracing/coresight/coresight-tpda.c | 58 ++++++++++++++++++++++++++++
  drivers/hwtracing/coresight/coresight-tpda.h |  4 ++
  2 files changed, 62 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-tpda.c b/drivers/hwtracing/coresight/coresight-tpda.c
index f712e11..8dcfc4a 100644
--- a/drivers/hwtracing/coresight/coresight-tpda.c
+++ b/drivers/hwtracing/coresight/coresight-tpda.c
@@ -21,6 +21,47 @@
DEFINE_CORESIGHT_DEVLIST(tpda_devs, "tpda"); +/* Search and read element data size from the TPDM node in
+ * the devicetree. Each input port of TPDA is connected to
+ * a TPDM. Different TPDM supports different types of dataset,
+ * and some may support more than one type of dataset.
+ * Parameter "inport" is used to pass in the input port number
+ * of TPDA, and it is set to 0 in the recursize call.
+ * Parameter "parent" is used to pass in the original call.
+ */

I am still not clear why we need to do this recursively ?

+static int tpda_set_element_size(struct tpda_drvdata *drvdata,
+			   struct coresight_device *csdev, int inport, bool parent)

Please could we renamse csdev => tpda_dev

+{
+	static int nr_inport;
+	int i;
+	struct coresight_device *in_csdev;

similarly tpdm_dev ?

Could we not add a check here to see if the dsb_esize[inport] is already
set and then bail out, reading this over and over ?

+
+	if (inport > (TPDA_MAX_INPORTS - 1))
+		return -EINVAL;
+
+	if (parent)
+		nr_inport = inport;
+
+	for (i = 0; i < csdev->pdata->nr_inconns; i++) {
+		in_csdev = csdev->pdata->in_conns[i].remote_dev;

Please note, the names of the structure field might change in the
next version of James' series

+		if (!in_csdev)
+			break;
+
+		if (parent)
+			if (csdev->pdata->in_conns[i].port != inport)
+				continue;
+
+		if (in_csdev && strstr(dev_name(&in_csdev->dev), "tpdm")) {

Isn't there a better way to distinguish a device to be TPDM ? May be we
could even add a source_sub_type - SOURCE_TPDM instead of using
SOURCE_OTHERS ? Do you expect other sources to be connected to TPDA?
e.g., STMs ?

+			of_property_read_u32(in_csdev->dev.parent->of_node,
+					"qcom,dsb-element-size", &drvdata->dsb_esize[nr_inport]);
+			break;
+		}
+		tpda_set_element_size(drvdata, in_csdev, 0, false);

What is the point of this ? Is this for covering the a TPDA connected to
another TPDA ?

e.g., { TPDM0, TPDM1 } -> TPDA0 -> TPDA1 ?

And you want to figure out the DSB size of TPDM0 when you want to enable
TPDA1 ? How do you choose between that size of TPDM0 vs TPDM1 ?

Please add a proper documentation for this function ? If TPDA0 is in the
the path, it should have been enabled before you reach TPDA1. Thus,
the dsb_esize array must have been initialised for TPDA0 and thus, you
could simply read it from the dsb_esize[] of TPDA0.
You could always look at the device_type and sub_type to detect a
TPDA{0} connected into TPDA{1}



+	}
+
+	return 0;
+}
+
  /* Settings pre enabling port control register */
  static void tpda_enable_pre_port(struct tpda_drvdata *drvdata)
  {
@@ -37,6 +78,18 @@ static void tpda_enable_port(struct tpda_drvdata *drvdata, int port)
  	u32 val;
val = readl_relaxed(drvdata->base + TPDA_Pn_CR(port));
+	/*
+	 * Configure aggregator port n DSB data set element size
+	 * Set the bit to 0 if the size is 32
+	 * Set the bit to 1 if the size is 64
+	 */
+	if (drvdata->dsb_esize[port] == 32)
+		val &= ~TPDA_Pn_CR_DSBSIZE;
+	else if (drvdata->dsb_esize[port] == 64)
+		val |= TPDA_Pn_CR_DSBSIZE;
+	else
+		dev_err(drvdata->dev,
+			"DSB data size input from port[%d] is invalid\n", port);

WARN_ON_ONCE() and abort the enable opration ? Or say, "fallback to 32bit or 64bit" if one of them is a safer option ? Please don't
leave it unknown.

  	/* Enable the port */
  	val |= TPDA_Pn_CR_ENA;
  	writel_relaxed(val, drvdata->base + TPDA_Pn_CR(port));
@@ -57,6 +110,11 @@ static void __tpda_enable(struct tpda_drvdata *drvdata, int port)
  static int tpda_enable(struct coresight_device *csdev, int inport, int outport)
  {
  	struct tpda_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+	int ret;
+
+	ret = tpda_set_element_size(drvdata, csdev, inport, true);
+	if (ret)
+		return ret;
spin_lock(&drvdata->spinlock);
  	if (atomic_read(&csdev->refcnt[inport]) == 0)
diff --git a/drivers/hwtracing/coresight/coresight-tpda.h b/drivers/hwtracing/coresight/coresight-tpda.h
index 0399678..9ec5870 100644
--- a/drivers/hwtracing/coresight/coresight-tpda.h
+++ b/drivers/hwtracing/coresight/coresight-tpda.h
@@ -10,6 +10,8 @@
  #define TPDA_Pn_CR(n)		(0x004 + (n * 4))
  /* Aggregator port enable bit */
  #define TPDA_Pn_CR_ENA		BIT(0)
+/* Aggregator port DSB data set element size bit */
+#define TPDA_Pn_CR_DSBSIZE		BIT(8)
#define TPDA_MAX_INPORTS 32 @@ -23,6 +25,7 @@
   * @csdev:      component vitals needed by the framework.
   * @spinlock:   lock for the drvdata value.
   * @enable:     enable status of the component.
+ * @dsb_esize:   DSB element size

Please state, must be 32 or 64.

   */
  struct tpda_drvdata {
  	void __iomem		*base;
@@ -30,6 +33,7 @@ struct tpda_drvdata {
  	struct coresight_device	*csdev;
  	spinlock_t		spinlock;
  	u8			atid;
+	u32			dsb_esize[TPDA_MAX_INPORTS];

Couldn't this be u8 ?


Suzuki

  };
#endif /* _CORESIGHT_CORESIGHT_TPDA_H */




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