[PATCH 6.12 045/460] ASoC: simple-card-utils: fix graph_util_is_ports0() for DT overlays

Greg Kroah-Hartman
2026-03-23T14:14:56Z

6.12-stable review patch. If anyone has any objections, please let me know.

------------------

From: Sen Wang <sen@ti.com>

[ Upstream commit 4185b95f8a42d92d68c49289b4644546b51e252b ]

graph_util_is_ports0() identifies DPCM front-end (ports@0) vs back-end
(ports@1) by calling of_get_child_by_name() to find the first "ports"
child and comparing pointers. This relies on child iteration order
matching DTS source order.

When the DPCM topology comes from a DT overlay, __of_attach_node()
inserts new children at the head of the sibling list, reversing the
order. of_get_child_by_name() then returns ports@1 instead of ports@0,
causing all front-end links to be classified as back-ends. The card
registers with no PCM devices.

Fix this by matching the unit address directly from the node name
instead of relying on sibling order.

Fixes: 92939252458f ("ASoC: simple-card-utils: add asoc_graph_is_ports0()")
Signed-off-by: Sen Wang <sen@ti.com>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://patch.msgid.link/20260309042109.2576612-1-sen@ti.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
sound/soc/generic/simple-card-utils.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/sound/soc/generic/simple-card-utils.c b/sound/soc/generic/simple-card-utils.c
index 4857ceecbdc4a..c9f92d445f4c9 100644
--- a/sound/soc/generic/simple-card-utils.c
+++ b/sound/soc/generic/simple-card-utils.c
@@ -1008,11 +1008,15 @@ int graph_util_is_ports0(struct device_node *np)
else
port = np;

- struct device_node *ports __free(device_node) = of_get_parent(port);
- struct device_node *top __free(device_node) = of_get_parent(ports);
- struct device_node *ports0 __free(device_node) = of_get_child_by_name(top, "ports");
+ struct device_node *ports __free(device_node) = of_get_parent(port);
+ const char *at = strchr(kbasename(ports->full_name), '@');

- return ports0 == ports;
+ /*
+ * Since child iteration order may differ
+ * between a base DT and DT overlays,
+ * string match "ports" or "ports@0" in the node name instead.
+ */
+ return !at || !strcmp(at, "@0");
}
EXPORT_SYMBOL_GPL(graph_util_is_ports0);

--
2.51.0