media: v4l2-mem2mem: Don't copy frame flags in v4l2_m2m_buf_copy_metadata()

The v4l2_m2m_buf_copy_metadata() function takes a boolean
copy_frame_flags argument. When true, it causes the function to copy the
V4L2_BUF_FLAG_KEYFRAME, V4L2_BUF_FLAG_BFRAME and V4L2_BUF_FLAG_PFRAME
flags from the output buffer to the capture buffer.

There is no use cases in any upstream driver for copying the flags.
KEY/P/B frames are properties of the bitstream buffer in some formats.
Once decoded, this is no longer a property of the video frame and should
be discarded.

It was considered useful to know if an uncompressed frame was decoded
from a KEY/P/B compressed frame, and to preserve that information if
that same uncompressed frame was passed through another M2M device (e.g.
a scaler). However, the V4L2 documentation makes it clear that the flags
are meant for compressed frames only.

Drop the copy_frame_flags argument from v4l2_m2m_buf_copy_metadata().
The change to drivers was performed with the following Coccinelle
semantic patch:

@@
expression src;
expression dst;
expression flag;
@@
-       v4l2_m2m_buf_copy_metadata(src, dst, flag);
+       v4l2_m2m_buf_copy_metadata(src, dst);

include/media/v4l2-mem2mem.h and drivers/media/v4l2-core/v4l2-mem2mem.c
have been updated manually.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>

1 files changed, 3 insertions, 9 deletions

diff --git a/include/media/v4l2-mem2mem.h b/include/media/v4l2-mem2mem.h
index c82445929c68..bf6a09a04dcf 100644
--- a/include/media/v4l2-mem2mem.h
+++ b/include/media/v4l2-mem2mem.h
@@ -845,19 +845,13 @@ v4l2_m2m_dst_buf_remove_by_idx(struct v4l2_m2m_ctx *m2m_ctx, unsigned int idx)
  *
  * @out_vb: the output buffer that is the source of the metadata.
  * @cap_vb: the capture buffer that will receive the metadata.
- * @copy_frame_flags: copy the KEY/B/PFRAME flags as well.
  *
  * This helper function copies the timestamp, timecode (if the TIMECODE
- * buffer flag was set), field and the TIMECODE, KEYFRAME, BFRAME, PFRAME
- * and TSTAMP_SRC_MASK flags from @out_vb to @cap_vb.
- *
- * If @copy_frame_flags is false, then the KEYFRAME, BFRAME and PFRAME
- * flags are not copied. This is typically needed for encoders that
- * set this bits explicitly.
+ * buffer flag was set), field, and the TIMECODE and TSTAMP_SRC_MASK flags from
+ * @out_vb to @cap_vb.
  */
 void v4l2_m2m_buf_copy_metadata(const struct vb2_v4l2_buffer *out_vb,
-				struct vb2_v4l2_buffer *cap_vb,
-				bool copy_frame_flags);
+				struct vb2_v4l2_buffer *cap_vb);
 
 /* v4l2 request helper */