[media] v4l: Add timestamp source flags, mask and document them

Some devices do not produce timestamps that correspond to the end of the
frame. The user space should be informed on the matter. This patch achieves
that by adding buffer flags (and a mask) for timestamp sources since more
possible timestamping points are expected than just two.

A three-bit mask is defined (V4L2_BUF_FLAG_TSTAMP_SRC_MASK) and two of the
eight possible values is are defined V4L2_BUF_FLAG_TSTAMP_SRC_EOF for end of
frame (value zero) V4L2_BUF_FLAG_TSTAMP_SRC_SOE for start of exposure (next
value).

Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Kamil Debski <k.debski@samsung.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 521350a74c46..42a856813d06 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -2227,7 +2227,9 @@ int vb2_queue_init(struct vb2_queue *q)
             WARN_ON(!q->io_modes)         ||
             WARN_ON(!q->ops->queue_setup) ||
             WARN_ON(!q->ops->buf_queue)   ||
-            WARN_ON(q->timestamp_flags & ~V4L2_BUF_FLAG_TIMESTAMP_MASK))
+            WARN_ON(q->timestamp_flags &
+                    ~(V4L2_BUF_FLAG_TIMESTAMP_MASK |
+                      V4L2_BUF_FLAG_TSTAMP_SRC_MASK)))
                 return -EINVAL;
 
         /* Warn that the driver should choose an appropriate timestamp type */