[media] media: Add pad flag MEDIA_PAD_FL_MUST_CONNECT

Pads that set this flag must be connected by an active link for the entity
to stream.

Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

2 files changed, 10 insertions, 0 deletions

diff --git a/Documentation/DocBook/media/v4l/media-ioc-enum-links.xml b/Documentation/DocBook/media/v4l/media-ioc-enum-links.xml
index 355df43badc5..cf8548556c7d 100644
--- a/Documentation/DocBook/media/v4l/media-ioc-enum-links.xml
+++ b/Documentation/DocBook/media/v4l/media-ioc-enum-links.xml
@@ -134,6 +134,15 @@
             <entry>Output pad, relative to the entity. Output pads source data
             and are origins of links.</entry>
           </row>
+          <row>
+            <entry><constant>MEDIA_PAD_FL_MUST_CONNECT</constant></entry>
+            <entry>If this flag is set and the pad is linked to any other
+            pad, then at least one of those links must be enabled for the
+            entity to be able to stream. There could be temporary reasons
+            (e.g. device configuration dependent) for the pad to need
+            enabled links even when this flag isn't set; the absence of the
+            flag doesn't imply there is none.</entry>
+          </row>
         </tbody>
       </tgroup>
     </table>
diff --git a/include/uapi/linux/media.h b/include/uapi/linux/media.h
index ed49574ad757..d847c760e8f0 100644
--- a/include/uapi/linux/media.h
+++ b/include/uapi/linux/media.h
@@ -98,6 +98,7 @@ struct media_entity_desc {
 
 #define MEDIA_PAD_FL_SINK               (1 << 0)
 #define MEDIA_PAD_FL_SOURCE             (1 << 1)
+#define MEDIA_PAD_FL_MUST_CONNECT       (1 << 2)
 
 struct media_pad_desc {
         __u32 entity;           /* entity ID */