Re: [PATCH] coresight: fix trace ID search skipping pass-through NoC devices
From: Leo Yan <leo.yan@arm.com>
Date: 2026-09-02 08:22:12
Also in:
lkml
Subsystem:
arm/coresight framework and drivers, hardware tracing facilities, the rest · Maintainers:
Suzuki K Poulose, Alexander Shishkin, Linus Torvalds
Hi Jie, On Mon, Aug 17, 2026 at 04:50:15PM +0800, Jie Gan wrote: [...]
quoted hunk ↗ jump to hunk
@@ -953,8 +953,12 @@ int coresight_path_assign_trace_id(struct coresight_path *path, /* Assign a trace ID to the path for the first device that wants to do it */ trace_id = coresight_get_trace_id(nd->csdev, mode, sink); - /* 0 means the device has no ID assignment, so keep searching */ - if (trace_id == 0) + /* + * 0 means the device has no ID assignment, and -EOPNOTSUPP + * means the device explicitly declines to assign one (e.g. a + * pass-through NoC) - in both cases keep searching downstream. + */ + if (trace_id == 0 || trace_id == -EOPNOTSUPP) continue;
Based on IS_VALID_CS_TRACE_ID(), I see 0 is for no ID assignment, could you improve a bit tnoc.c instead? If so, We don't need to add a new error for the same purpose. ---8<---
diff --git a/drivers/hwtracing/coresight/coresight-tnoc.c b/drivers/hwtracing/coresight/coresight-tnoc.c
index 9e8de4323d28..bf221c1e5c48 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) { 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)