[PATCH v2 0/1] staging: media: tegra-video: vi: improve VI graph building logic

[PATCH v2 0/1] staging: media: tegra-video: vi: improve VI graph building logic

[Svyatoslav Ryhel]

The existing tegra_vi_graph_build function relies heavily on a one-to-one
match between Device Tree nodes and media pad links. While this works for
simpler configurations, it causes issues when Device Tree nodes do not
match media pad link logic (e.g., mt9m114). Switch to the
media_entity_get_fwnode_pad helper to verify and retrieve the correct pad
linked to an endpoint, rather than assuming the endpoint ID matches the
pad ID.

---
Changes in v2:
- fixed use of NULL fw pointers in debug prints
---

Svyatoslav Ryhel (1):
  staging: media: tegra-video: vi: Improve media graph building logic

 drivers/staging/media/tegra-video/vi.c | 78 ++++++++++++--------------
 1 file changed, 35 insertions(+), 43 deletions(-)

-- 
2.51.0

[PATCH v2 1/1] staging: media: tegra-video: vi: Improve media graph building logic

[Svyatoslav Ryhel]

The existing tegra_vi_graph_build function relies heavily on a one-to-one
match between Device Tree nodes and media pad links. While this works for
simpler configurations, it causes issues when Device Tree nodes do not
match media pad link logic (e.g., mt9m114). Switch to the
media_entity_get_fwnode_pad helper to verify and retrieve the correct pad
linked to an endpoint, rather than assuming the endpoint ID matches the
pad ID.

Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
---
 drivers/staging/media/tegra-video/vi.c | 78 ++++++++++++--------------
 1 file changed, 35 insertions(+), 43 deletions(-)

diff --git a/drivers/staging/media/tegra-video/vi.c b/drivers/staging/media/tegra-video/vi.c
index f14cdc7b5211..24e4bd438678 100644
--- a/drivers/staging/media/tegra-video/vi.c
+++ b/drivers/staging/media/tegra-video/vi.c
@@ -1468,7 +1468,6 @@ static int tegra_vi_graph_build(struct tegra_vi_channel *chan,
 	struct tegra_vi *vi = chan->vi;
 	struct tegra_vi_graph_entity *ent;
 	struct fwnode_handle *ep = NULL;
-	struct v4l2_fwnode_link link;
 	struct media_entity *local = entity->entity;
 	struct media_entity *remote;
 	struct media_pad *local_pad;
@@ -1478,70 +1477,64 @@ static int tegra_vi_graph_build(struct tegra_vi_channel *chan,
 
 	dev_dbg(vi->dev, "creating links for entity %s\n", local->name);
 
-	while (1) {
-		ep = fwnode_graph_get_next_endpoint(entity->asd.match.fwnode,
-						    ep);
-		if (!ep)
-			break;
+	fwnode_graph_for_each_endpoint(entity->asd.match.fwnode, ep) {
+		struct fwnode_handle *remote_parent __free(fwnode_handle) = NULL;
+		struct fwnode_handle *sink_ep __free(fwnode_handle) = NULL;
+		int src_idx, sink_idx;
 
-		ret = v4l2_fwnode_parse_link(ep, &link);
-		if (ret < 0) {
-			dev_err(vi->dev, "failed to parse link for %pOF: %d\n",
-				to_of_node(ep), ret);
+		src_idx = media_entity_get_fwnode_pad(local, ep,
+						      MEDIA_PAD_FL_SOURCE);
+		if (src_idx < 0) {
+			dev_dbg(vi->dev, "no source pad found for %pfw\n", ep);
 			continue;
 		}
 
-		if (link.local_port >= local->num_pads) {
-			dev_err(vi->dev, "invalid port number %u on %pOF\n",
-				link.local_port, to_of_node(link.local_node));
-			v4l2_fwnode_put_link(&link);
-			ret = -EINVAL;
-			break;
+		remote_parent = fwnode_graph_get_remote_port_parent(ep);
+		if (!remote_parent) {
+			dev_dbg(vi->dev, "no remote parent found for %pfw\n",
+				ep);
+			continue;
 		}
 
-		local_pad = &local->pads[link.local_port];
+		local_pad = &local->pads[src_idx];
 		/* Remote node is vi node. So use channel video entity and pad
 		 * as remote/sink.
 		 */
-		if (link.remote_node == of_fwnode_handle(vi->dev->of_node)) {
+		if (remote_parent == of_fwnode_handle(vi->dev->of_node)) {
 			remote = &chan->video.entity;
 			remote_pad = &chan->pad;
 			goto create_link;
 		}
 
-		/*
-		 * Skip sink ports, they will be processed from the other end
-		 * of the link.
-		 */
-		if (local_pad->flags & MEDIA_PAD_FL_SINK) {
-			dev_dbg(vi->dev, "skipping sink port %pOF:%u\n",
-				to_of_node(link.local_node), link.local_port);
-			v4l2_fwnode_put_link(&link);
-			continue;
-		}
-
 		/* find the remote entity from notifier list */
 		ent = tegra_vi_graph_find_entity(&chan->notifier.done_list,
-						 link.remote_node);
+						 remote_parent);
 		if (!ent) {
-			dev_err(vi->dev, "no entity found for %pOF\n",
-				to_of_node(link.remote_node));
-			v4l2_fwnode_put_link(&link);
+			fwnode_handle_put(ep);
+			dev_err(vi->dev, "no entity found for %pfw\n",
+				remote_parent);
 			ret = -ENODEV;
 			break;
 		}
 
 		remote = ent->entity;
-		if (link.remote_port >= remote->num_pads) {
-			dev_err(vi->dev, "invalid port number %u on %pOF\n",
-				link.remote_port,
-				to_of_node(link.remote_node));
-			v4l2_fwnode_put_link(&link);
-			ret = -EINVAL;
-			break;
+
+		sink_ep = fwnode_graph_get_remote_endpoint(ep);
+		if (!sink_ep) {
+			dev_dbg(vi->dev, "no sink ep found for %pfw\n",
+				ep);
+			continue;
+		}
+
+		sink_idx = media_entity_get_fwnode_pad(remote, sink_ep,
+						       MEDIA_PAD_FL_SINK);
+		if (sink_idx < 0) {
+			dev_dbg(vi->dev, "no sink pad found for %pfw\n",
+				sink_ep);
+			continue;
 		}
 
-		remote_pad = &remote->pads[link.remote_port];
+		remote_pad = &remote->pads[sink_idx];
 
 create_link:
 		dev_dbg(vi->dev, "creating %s:%u -> %s:%u link\n",
@@ -1551,8 +1544,8 @@ static int tegra_vi_graph_build(struct tegra_vi_channel *chan,
 		ret = media_create_pad_link(local, local_pad->index,
 					    remote, remote_pad->index,
 					    link_flags);
-		v4l2_fwnode_put_link(&link);
 		if (ret < 0) {
+			fwnode_handle_put(ep);
 			dev_err(vi->dev,
 				"failed to create %s:%u -> %s:%u link: %d\n",
 				local->name, local_pad->index,
@@ -1561,7 +1554,6 @@ static int tegra_vi_graph_build(struct tegra_vi_channel *chan,
 		}
 	}
 
-	fwnode_handle_put(ep);
 	return ret;
 }
 
-- 
2.51.0

Re: [PATCH v2 1/1] staging: media: tegra-video: vi: Improve media graph building logic

[Luca Ceresoli]

On Sat May 23, 2026 at 8:47 AM CEST, Svyatoslav Ryhel wrote:
> The existing tegra_vi_graph_build function relies heavily on a one-to-one
> match between Device Tree nodes and media pad links. While this works for
> simpler configurations, it causes issues when Device Tree nodes do not
> match media pad link logic (e.g., mt9m114). Switch to the
> media_entity_get_fwnode_pad helper to verify and retrieve the correct pad
> linked to an endpoint, rather than assuming the endpoint ID matches the
> pad ID.
>
> Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>

I still haven't looked at the code, but:

Tested-by: Luca Ceresoli <luca.ceresoli@bootlin.com> # tegra20, parallel camera

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com