Re: [PATCH v2] coresight: tnoc: fix trace ID path assignment failure on non-AMBA tnoc

[Jie Gan <jie.gan@oss.qualcomm.com>]

On 9/2/2026 5:41 PM, Jie Gan wrote:
> For a tnoc device not on the AMBA bus, atid was set to -EOPNOTSUPP.
> trace_noc_id() returns this value directly to
> coresight_path_assign_trace_id(), which only treats a literal 0
> return as "this device has no ID, keep searching the path" -
> any other value is checked against IS_VALID_CS_TRACE_ID() and
> rejected. A negative atid therefore made path assignment fail with
> -EINVAL instead of falling through to the next device in the path
> that could supply a valid trace ID.
> 
> Use 0, the same sentinel coresight_path_assign_trace_id() already
> recognizes as "not allocated", instead of -EOPNOTSUPP.
> 


Gentle ping


> Fixes: 5799dee92dc2 ("coresight-tnoc: add platform driver to support Interconnect TNOC")
> Signed-off-by: Jie Gan <jie.gan@oss.qualcomm.com>
> ---
> Changes in v2:
> - fixes the issue in TNOC driver instead of in generic framework.
> Link to v1 - https://lore.kernel.org/all/20260817-fix-trace-id-assign-issue-v1-1-b2164e33f9fa@oss.qualcomm.com/
> ---
>   drivers/hwtracing/coresight/coresight-tnoc.c | 10 ++++------
>   1 file changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-tnoc.c b/drivers/hwtracing/coresight/coresight-tnoc.c
> index 9e8de4323d28..8924b61ad076 100644
> --- a/drivers/hwtracing/coresight/coresight-tnoc.c
> +++ b/drivers/hwtracing/coresight/coresight-tnoc.c
> @@ -51,8 +51,8 @@ static void trace_noc_enable_hw(struct trace_noc_drvdata *drvdata)
>   {
>   	u32 val;
>   
> -	/* No valid ATID, simply enable the unit */
> -	if (drvdata->atid == -EOPNOTSUPP) {
> +	/* 0 means no ID assignment, simply enable the unit */
> +	if (drvdata->atid == 0) {
>   		writel(TRACE_NOC_CTRL_PORTEN, drvdata->base + TRACE_NOC_CTRL);
>   		return;
>   	}
> @@ -130,10 +130,8 @@ static int trace_noc_init_default_data(struct trace_noc_drvdata *drvdata)
>   {
>   	int atid;
>   
> -	if (!dev_is_amba(drvdata->dev)) {
> -		drvdata->atid = -EOPNOTSUPP;
> +	if (!dev_is_amba(drvdata->dev))
>   		return 0;
> -	}
>   
>   	atid = coresight_trace_id_get_system_id();
>   	if (atid < 0)
> @@ -166,7 +164,7 @@ static umode_t trace_id_is_visible(struct kobject *kobj,
>   	struct device *dev = kobj_to_dev(kobj);
>   	struct trace_noc_drvdata *drvdata = dev_get_drvdata(dev->parent);
>   
> -	if (attr == &dev_attr_traceid.attr && drvdata->atid < 0)
> +	if (attr == &dev_attr_traceid.attr && drvdata->atid == 0)
>   		return 0;
>   
>   	return attr->mode;
> 
> ---
> base-commit: 8b72f6626dc39b9e7e82b2721d4f7c3b86286012
> change-id: 20260902-fix-trace-id-error-in-tnoc-driver-eda88ea30662
> 
> Best regards,