[RFC 1/7] media: mc: Add INTERNAL_SOURCE pad type flag

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Internal source pads will be used as routing endpoints in V4L2
[GS]_ROUTING IOCTLs, to indicate that the stream begins in the entity.

Also prevent creating links to pads that have been flagged as internal.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 .../userspace-api/media/mediactl/media-types.rst          | 7 +++++++
 drivers/media/mc/mc-entity.c                              | 8 +++++++-
 include/uapi/linux/media.h                                | 1 +
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/Documentation/userspace-api/media/mediactl/media-types.rst b/Documentation/userspace-api/media/mediactl/media-types.rst
index 0ffeece1e0c8..c724139ad46c 100644
--- a/Documentation/userspace-api/media/mediactl/media-types.rst
+++ b/Documentation/userspace-api/media/mediactl/media-types.rst
@@ -361,6 +361,7 @@ Types and flags used to represent the media graph elements
 .. _MEDIA-PAD-FL-SINK:
 .. _MEDIA-PAD-FL-SOURCE:
 .. _MEDIA-PAD-FL-MUST-CONNECT:
+.. _MEDIA-PAD-FL-INTERNAL-SOURCE:
 
 .. flat-table:: Media pad flags
     :header-rows:  0
@@ -382,6 +383,12 @@ Types and flags used to represent the media graph elements
 	  when this flag isn't set; the absence of the flag doesn't imply
 	  there is none.
 
+    *  -  ``MEDIA_PAD_FL_INTERNAL_SOURCE``
+       -  This flag indicates an internal pad that has no external
+	  connections. Such a pad may not be connected with a link. The internal
+	  flag indicates that the stream either starts or ends in the
+	  entity. For a given pad, the INTERNAL_SOURCE flag may not be set if
+	  either SINK or SOURCE flags is set.
 
 One and only one of ``MEDIA_PAD_FL_SINK`` and ``MEDIA_PAD_FL_SOURCE``
 must be set for every pad.
diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c
index ef34ddd715c9..ed99160a2487 100644
--- a/drivers/media/mc/mc-entity.c
+++ b/drivers/media/mc/mc-entity.c
@@ -1062,7 +1062,8 @@ int media_get_pad_index(struct media_entity *entity, u32 pad_type,
 
 	for (i = 0; i < entity->num_pads; i++) {
 		if ((entity->pads[i].flags &
-		     (MEDIA_PAD_FL_SINK | MEDIA_PAD_FL_SOURCE)) != pad_type)
+		     (MEDIA_PAD_FL_SINK | MEDIA_PAD_FL_SOURCE |
+		      MEDIA_PAD_FL_INTERNAL_SOURCE)) != pad_type)
 			continue;
 
 		if (entity->pads[i].sig_type == sig_type)
@@ -1087,6 +1088,11 @@ media_create_pad_link(struct media_entity *source, u16 source_pad,
 		return -EINVAL;
 	if (WARN_ON(!(sink->pads[sink_pad].flags & MEDIA_PAD_FL_SINK)))
 		return -EINVAL;
+	if (WARN_ON(sink->pads[sink_pad].flags &
+		    MEDIA_PAD_FL_INTERNAL_SOURCE) ||
+	    WARN_ON(source->pads[source_pad].flags &
+		    MEDIA_PAD_FL_INTERNAL_SOURCE))
+		return -EINVAL;
 
 	link = media_add_link(&source->links);
 	if (link == NULL)
diff --git a/include/uapi/linux/media.h b/include/uapi/linux/media.h
index edb8dfef9eba..0e2577e8b425 100644
--- a/include/uapi/linux/media.h
+++ b/include/uapi/linux/media.h
@@ -208,6 +208,7 @@ struct media_entity_desc {
 #define MEDIA_PAD_FL_SINK			(1U << 0)
 #define MEDIA_PAD_FL_SOURCE			(1U << 1)
 #define MEDIA_PAD_FL_MUST_CONNECT		(1U << 2)
+#define MEDIA_PAD_FL_INTERNAL_SOURCE		(1U << 3)
 
 struct media_pad_desc {
 	__u32 entity;		/* entity ID */
-- 
2.30.2