Re: [PATCH v5 4/7] coresight-tgu: Add TGU decode support

On 5/29/2025 7:32 PM, Jonathan Cameron wrote:

On Thu, 29 May 2025 16:19:45 +0800
Songwei Chai [off-list ref] wrote:

quoted

Decoding is when all the potential pieces for creating a trigger
are brought together for a given step. Example - there may be a
counter keeping track of some occurrences and a priority-group that
is being used to detect a pattern on the sense inputs. These 2
inputs to condition_decode must be programmed, for a given step,
to establish the condition for the trigger, or movement to another
steps.

Signed-off-by: Songwei Chai <redacted>

diff --git a/drivers/hwtracing/coresight/coresight-tgu.c b/drivers/hwtracing/coresight/coresight-tgu.c
index 6dbfd4c604b1..8dbe8ab30174 100644
--- a/drivers/hwtracing/coresight/coresight-tgu.c
+++ b/drivers/hwtracing/coresight/coresight-tgu.c

@@ -21,13 +21,35 @@ static int calculate_array_location(struct tgu_drvdata *drvdata,
+
  static int tgu_enable(struct coresight_device *csdev, enum cs_mode mode,
  		      void *data)
  {
+	int ret = 0;

 From what can be seen here, looks like ret is always set, so no need to init.

Would this initialization improve the determinism of the code? :-)

quoted

  	struct tgu_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
  
  	spin_lock(&drvdata->spinlock);

@@ -150,11 +264,15 @@ static int tgu_enable(struct coresight_device *csdev, enum cs_mode mode,
  		spin_unlock(&drvdata->spinlock);
  		return -EBUSY;
  	}
-	tgu_write_all_hw_regs(drvdata);
+	ret = tgu_write_all_hw_regs(drvdata);
+
+	if (ret == -EINVAL)
+		goto exit;
  	drvdata->enable = true;
  
+exit:
  	spin_unlock(&drvdata->spinlock);
-	return 0;
+	return ret;
  }

diff --git a/drivers/hwtracing/coresight/coresight-tgu.h b/drivers/hwtracing/coresight/coresight-tgu.h
index f07ead505365..691da393ffa3 100644
--- a/drivers/hwtracing/coresight/coresight-tgu.h
+++ b/drivers/hwtracing/coresight/coresight-tgu.h
  enum operation_index {
  	TGU_PRIORITY0,
  	TGU_PRIORITY1,
  	TGU_PRIORITY2,
-	TGU_PRIORITY3
+	TGU_PRIORITY3,

And here is why the previous patch should definitely have had the ,

Thanks for your clarification.

quoted

+	TGU_CONDITION_DECODE
  
  };