media: mc: Add local pad to pipeline regardless of the link state

When building pipelines by following links, the
media_pipeline_explore_next_link() function only traverses enabled
links. The remote pad of a disabled link is not added to the pipeline,
and neither is the local pad. While the former is correct as disabled
links should not be followed, not adding the local pad breaks processing
of the MEDIA_PAD_FL_MUST_CONNECT flag.

The MEDIA_PAD_FL_MUST_CONNECT flag is checked in the
__media_pipeline_start() function that iterates over all pads after
populating the pipeline. If the pad is not present, the check gets
skipped, rendering it useless.

Fix this by adding the local pad of all links regardless of their state,
only skipping the remote pad for disabled links.

Cc: [email protected] # 6.1
Fixes: ae219872834a ("media: mc: entity: Rewrite media_pipeline_start()")
Reported-by: Frieder Schrempf <[email protected]>
Closes: https://lore.kernel.org/linux-media/[email protected]
Signed-off-by: Laurent Pinchart <[email protected]>
Acked-by: Sakari Ailus <[email protected]>
Signed-off-by: Hans Verkuil <[email protected]>

1 files changed, 9 insertions, 9 deletions

diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c
index 543a392f8635..a6f28366106f 100644
--- a/drivers/media/mc/mc-entity.c
+++ b/drivers/media/mc/mc-entity.c
@@ -620,13 +620,6 @@ static int media_pipeline_explore_next_link(struct media_pipeline *pipe,
 		link->source->entity->name, link->source->index,
 		link->sink->entity->name, link->sink->index);
 
-	/* Skip links that are not enabled. */
-	if (!(link->flags & MEDIA_LNK_FL_ENABLED)) {
-		dev_dbg(walk->mdev->dev,
-			"media pipeline: skipping link (disabled)\n");
-		return 0;
-	}
-
 	/* Get the local pad and remote pad. */
 	if (link->source->entity == pad->entity) {
 		local = link->source;
@@ -648,13 +641,20 @@ static int media_pipeline_explore_next_link(struct media_pipeline *pipe,
 	}
 
 	/*
-	 * Add the local and remote pads of the link to the pipeline and push
-	 * them to the stack, if they're not already present.
+	 * Add the local pad of the link to the pipeline and push it to the
+	 * stack, if not already present.
 	 */
 	ret = media_pipeline_add_pad(pipe, walk, local);
 	if (ret)
 		return ret;
 
+	/* Similarly, add the remote pad, but only if the link is enabled. */
+	if (!(link->flags & MEDIA_LNK_FL_ENABLED)) {
+		dev_dbg(walk->mdev->dev,
+			"media pipeline: skipping link (disabled)\n");
+		return 0;
+	}
+
 	ret = media_pipeline_add_pad(pipe, walk, remote);
 	if (ret)
 		return ret;