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, 1 insertions, 1 deletions

diff --git a/drivers/media/platform/nvidia/tegra-vde/h264.c b/drivers/media/platform/nvidia/tegra-vde/h264.c
index 45f8f6904867..2a2211671fd9 100644
--- a/drivers/media/platform/nvidia/tegra-vde/h264.c
+++ b/drivers/media/platform/nvidia/tegra-vde/h264.c
@@ -776,7 +776,7 @@ static int tegra_vde_h264_setup_frames(struct tegra_ctx *ctx,
 	 * If userspace doesn't tell us frame's type, then we will try decode
 	 * as-is.
 	 */
-	v4l2_m2m_buf_copy_metadata(src, dst, true);
+	v4l2_m2m_buf_copy_metadata(src, dst);
 
 	if (h->decode_params->flags & V4L2_H264_DECODE_PARAM_FLAG_BFRAME)
 		tb->b_frame = true;