[PATCH v11 14/27] coresight: Move source helper disabling to coresight_disable_path()

Leo Yan
2026-05-01T16:48:59Z

Move source helper disabling to coresight_disable_path() to pair it with
coresight_enable_path().

In coresight_enable_path(), if enabling a node fails, iterate to the
next node (which is the last successfully enabled node) and pass it to
coresight_disable_path() for rollback. If the failed node is the last
node on the path, no device is actually enabled, so bail out directly.

As a result, coresight_disable_source() only controls the source,
leaving the associated helpers to be managed as part of path. Update
the comment to reflect this change.

Tested-by: Jie Gan <jie.gan@oss.qualcomm.com>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Reviewed-by: James Clark <james.clark@linaro.org>
Tested-by: James Clark <james.clark@linaro.org>
Signed-off-by: Leo Yan <leo.yan@arm.com>
---
drivers/hwtracing/coresight/coresight-core.c | 38 +++++++++++++---------------
1 file changed, 17 insertions(+), 21 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
index 0c11e7fff1bd5cf504b17241595d83a1d11bcf40..6ab80ae7c389e9031d4ab065d83bb676fd12160b 100644
--- a/drivers/hwtracing/coresight/coresight-core.c
+++ b/drivers/hwtracing/coresight/coresight-core.c
@@ -447,19 +447,12 @@ static void coresight_disable_helpers(struct coresight_device *csdev,
}

/*
- * Helper function to call source_ops(csdev)->disable and also disable the
- * helpers.
- *
- * There is an imbalance between coresight_enable_path() and
- * coresight_disable_path(). Enabling also enables the source's helpers as part
- * of the path, but disabling always skips the first item in the path (which is
- * the source), so sources and their helpers don't get disabled as part of that
- * function and we need the extra step here.
+ * coresight_disable_source() only disables the source, but do nothing for
+ * the associated helpers, which are controlled as part of the path.
*/
void coresight_disable_source(struct coresight_device *csdev, void *data)
{
source_ops(csdev)->disable(csdev, data);
- coresight_disable_helpers(csdev, NULL);
}
EXPORT_SYMBOL_GPL(coresight_disable_source);

@@ -486,9 +479,9 @@ int coresight_resume_source(struct coresight_device *csdev)
EXPORT_SYMBOL_GPL(coresight_resume_source);

/*
- * coresight_disable_path_from : Disable components in the given path beyond
- * @nd in the list. If @nd is NULL, all the components, except the SOURCE are
- * disabled.
+ * coresight_disable_path_from : Disable components in the given path starting
+ * from @nd in the list. If @nd is NULL, all the components, except the SOURCE
+ * are disabled.
*/
static void coresight_disable_path_from(struct coresight_path *path,
struct coresight_node *nd)
@@ -499,7 +492,7 @@ static void coresight_disable_path_from(struct coresight_path *path,
if (!nd)
nd = list_first_entry(&path->path_list, struct coresight_node, link);

- list_for_each_entry_continue(nd, &path->path_list, link) {
+ list_for_each_entry_from(nd, &path->path_list, link) {
csdev = nd->csdev;
type = csdev->type;

@@ -519,12 +512,6 @@ static void coresight_disable_path_from(struct coresight_path *path,
coresight_disable_sink(csdev);
break;
case CORESIGHT_DEV_TYPE_SOURCE:
- /*
- * We skip the first node in the path assuming that it
- * is the source. So we don't expect a source device in
- * the middle of a path.
- */
- WARN_ON(1);
break;
case CORESIGHT_DEV_TYPE_LINK:
parent = list_prev_entry(nd, link)->csdev;
@@ -580,12 +567,16 @@ int coresight_enable_path(struct coresight_path *path, enum cs_mode mode)
{
int ret = 0;
u32 type;
- struct coresight_node *nd;
+ struct coresight_node *nd, *last;
struct coresight_device *csdev, *parent, *child;
struct coresight_device *source;

source = coresight_get_source(path);
- list_for_each_entry_reverse(nd, &path->path_list, link) {
+
+ last = list_last_entry(&path->path_list, struct coresight_node, link);
+
+ nd = last;
+ list_for_each_entry_from_reverse(nd, &path->path_list, link) {
csdev = nd->csdev;
type = csdev->type;

@@ -639,6 +630,11 @@ int coresight_enable_path(struct coresight_path *path, enum cs_mode mode)
err_disable_helpers:
coresight_disable_helpers(csdev, path);
err_disable_path:
+ /* No device is actually enabled */
+ if (nd == last)
+ goto out;
+
+ nd = list_next_entry(nd, link);
coresight_disable_path_from(path, nd);
goto out;
}

--
2.34.1