[PATCH 2/7] media: mc: Add INTERNAL pad 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>
---
 Documentation/userspace-api/media/glossary.rst             | 6 ++++++
 Documentation/userspace-api/media/mediactl/media-types.rst | 6 ++++++
 drivers/media/mc/mc-entity.c                               | 6 +++++-
 include/uapi/linux/media.h                                 | 1 +
 4 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/Documentation/userspace-api/media/glossary.rst b/Documentation/userspace-api/media/glossary.rst
index 96a360edbf3b..f7b99a4527c7 100644
--- a/Documentation/userspace-api/media/glossary.rst
+++ b/Documentation/userspace-api/media/glossary.rst
@@ -173,6 +173,12 @@ Glossary
 	An integrated circuit that integrates all components of a computer
 	or other electronic systems.
 
+_media-glossary-stream:
+    Stream
+	A distinct flow of data (image data or metadata) over a media pipeline
+	from source to sink. A source may be e.g. an image sensor and a sink
+	e.g. a memory buffer.
+
     V4L2 API
 	**V4L2 userspace API**
 
diff --git a/Documentation/userspace-api/media/mediactl/media-types.rst b/Documentation/userspace-api/media/mediactl/media-types.rst
index 0ffeece1e0c8..28941da27790 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:
 
 .. flat-table:: Media pad flags
     :header-rows:  0
@@ -382,6 +383,11 @@ 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``
+       -  The internal flag indicates an internal pad that has no external
+	  connections. Such a pad shall not be connected with a link. The
+	  internal flag indicates that the :ref:``stream
+	  <media-glossary-stream>`` either starts or ends in the entity.
 
 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 4991281dcccc..03a9e0b8ebab 100644
--- a/drivers/media/mc/mc-entity.c
+++ b/drivers/media/mc/mc-entity.c
@@ -1071,7 +1071,8 @@ 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)) != pad_type)
 			continue;
 
 		if (entity->pads[i].sig_type == sig_type)
@@ -1094,6 +1095,9 @@ media_create_pad_link(struct media_entity *source, u16 source_pad,
 		return -EINVAL;
 	if (WARN_ON(!(source->pads[source_pad].flags & MEDIA_PAD_FL_SOURCE)))
 		return -EINVAL;
+	if (WARN_ON(source->pads[source_pad].flags & MEDIA_PAD_FL_SOURCE &&
+		    source->pads[source_pad].flags & MEDIA_PAD_FL_INTERNAL))
+		return -EINVAL;
 	if (WARN_ON(!(sink->pads[sink_pad].flags & MEDIA_PAD_FL_SINK)))
 		return -EINVAL;
 
diff --git a/include/uapi/linux/media.h b/include/uapi/linux/media.h
index 1c80b1d6bbaf..80cfd12a43fc 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			(1U << 3)
 
 struct media_pad_desc {
 	__u32 entity;		/* entity ID */
-- 
2.39.2