media: mc: Add INTERNAL pad flag

Internal sink pads will be used as routing endpoints in V4L2 [GS]_ROUTING
IOCTLs, to indicate that the stream begins in the entity. Internal sink
pads are pads that have both SINK and INTERNAL flags set.

Also prevent creating links to pads that have been flagged as internal and
initialising SOURCE pads with INTERNAL flag set.

Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Martin Hecht <mhecht73@gmail.com>
Reviewed-by: Mirela Rabulea <mirela.rabulea@nxp.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>

3 files changed, 22 insertions, 3 deletions

diff --git a/Documentation/userspace-api/media/mediactl/media-types.rst b/Documentation/userspace-api/media/mediactl/media-types.rst
index 6332e8395263..200c37a1da26 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
@@ -381,6 +382,14 @@ Types and flags used to represent the media graph elements
 	  enabled links even 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. As they are internal to entities, internal pads shall not
+	  be connected with links.
+
+	  The internal flag may currently be present only in a sink pad where it
+	  indicates that the :ref:``stream <media-glossary-stream>`` originates
+	  from within 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 3fa0bc687851..7938f785e2e3 100644
--- a/drivers/media/mc/mc-entity.c
+++ b/drivers/media/mc/mc-entity.c
@@ -209,11 +209,16 @@ int media_entity_pads_init(struct media_entity *entity, u16 num_pads,
 		mutex_lock(&mdev->graph_mutex);
 
 	media_entity_for_each_pad(entity, iter) {
+		const u32 pad_flags = iter->flags & (MEDIA_PAD_FL_SINK |
+						     MEDIA_PAD_FL_SOURCE |
+						     MEDIA_PAD_FL_INTERNAL);
+
 		iter->entity = entity;
 		iter->index = i++;
 
-		if (hweight32(iter->flags & (MEDIA_PAD_FL_SINK |
-					     MEDIA_PAD_FL_SOURCE)) != 1) {
+		if (pad_flags != MEDIA_PAD_FL_SINK &&
+		    pad_flags != (MEDIA_PAD_FL_SINK | MEDIA_PAD_FL_INTERNAL) &&
+		    pad_flags != MEDIA_PAD_FL_SOURCE) {
 			ret = -EINVAL;
 			break;
 		}
@@ -1118,7 +1123,8 @@ 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)
@@ -1148,6 +1154,9 @@ 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(source->pads[source_pad].flags & MEDIA_PAD_FL_INTERNAL) ||
+	    WARN_ON(sink->pads[sink_pad].flags & MEDIA_PAD_FL_INTERNAL))
+		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 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 */