[PATCHv4 01/10] videodev2.h: add tag support

[hverkuil-cisco@xs4all.nl]

From: Hans Verkuil <hverkuil-cisco@xs4all.nl>

Add support for 'tags' to struct v4l2_buffer. These can be used
by m2m devices so userspace can set a tag for an output buffer and
this value will then be copied to the capture buffer(s).

This tag can be used to refer to capture buffers, something that
is needed by stateless HW codecs.

The new V4L2_BUF_CAP_SUPPORTS_TAGS capability indicates whether
or not tags are supported.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reviewed-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Reviewed-by: Alexandre Courbot <acourbot@chromium.org>
---
 include/uapi/linux/videodev2.h | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 2db1635de956..9095d7abe10d 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -881,6 +881,7 @@ struct v4l2_requestbuffers {
 #define V4L2_BUF_CAP_SUPPORTS_DMABUF	(1 << 2)
 #define V4L2_BUF_CAP_SUPPORTS_REQUESTS	(1 << 3)
 #define V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS (1 << 4)
+#define V4L2_BUF_CAP_SUPPORTS_TAGS	(1 << 5)
 
 /**
  * struct v4l2_plane - plane info for multi-planar buffers
@@ -940,6 +941,7 @@ struct v4l2_plane {
  * @length:	size in bytes of the buffer (NOT its payload) for single-plane
  *		buffers (when type != *_MPLANE); number of elements in the
  *		planes array for multi-plane buffers
+ * @tag:	buffer tag
  * @request_fd: fd of the request that this buffer should use
  *
  * Contains data exchanged by application and driver using one of the Streaming
@@ -964,7 +966,10 @@ struct v4l2_buffer {
 		__s32		fd;
 	} m;
 	__u32			length;
-	__u32			reserved2;
+	union {
+		__u32		reserved2;
+		__u32		tag;
+	};
 	union {
 		__s32		request_fd;
 		__u32		reserved;
@@ -990,6 +995,8 @@ struct v4l2_buffer {
 #define V4L2_BUF_FLAG_IN_REQUEST		0x00000080
 /* timecode field is valid */
 #define V4L2_BUF_FLAG_TIMECODE			0x00000100
+/* tag field is valid */
+#define V4L2_BUF_FLAG_TAG			0x00000200
 /* Buffer is prepared for queuing */
 #define V4L2_BUF_FLAG_PREPARED			0x00000400
 /* Cache handling flags */
-- 
2.19.1