Hi,
On Mon, 2018-11-12 at 09:33 +0100, Hans Verkuil wrote:
> From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
>
> 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.
I am getting the following warning when building with this patch:
videodev2.h:1044:9: warning: cast to pointer from integer of different
size [-Wint-to-pointer-cast]
return (void *)v4l2_buffer_get_tag(buf);
That is because we are on a 32-bit architecture here, so pointers are
not 64-bit long, thus we can't have an equivalency between tag and
pointer.
It looks like this isn't used in the following patches, so perhaps it
should be dropped?
Cheers,
Paul
> Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
> ---
> include/uapi/linux/videodev2.h | 37 +++++++++++++++++++++++++++++++++-
> 1 file changed, 36 insertions(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index c8e8ff810190..a6f81f368e01 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -912,6 +912,11 @@ struct v4l2_plane {
> __u32 reserved[11];
> };
>
> +struct v4l2_buffer_tag {
> + __u32 low;
> + __u32 high;
> +};
> +
> /**
> * struct v4l2_buffer - video buffer info
> * @index: id number of the buffer
> @@ -950,7 +955,10 @@ struct v4l2_buffer {
> __u32 flags;
> __u32 field;
> struct timeval timestamp;
> - struct v4l2_timecode timecode;
> + union {
> + struct v4l2_timecode timecode;
> + struct v4l2_buffer_tag tag;
> + };
> __u32 sequence;
>
> /* memory location */
> @@ -988,6 +996,8 @@ 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 */
> @@ -1007,6 +1017,31 @@ struct v4l2_buffer {
> /* request_fd is valid */
> #define V4L2_BUF_FLAG_REQUEST_FD 0x00800000
>
> +static inline void v4l2_buffer_set_tag(struct v4l2_buffer *buf, __u64 tag)
> +{
> + buf->tag.high = tag >> 32;
> + buf->tag.low = tag & 0xffffffffULL;
> + buf->flags |= V4L2_BUF_FLAG_TAG;
> +}
> +
> +static inline void v4l2_buffer_set_tag_ptr(struct v4l2_buffer *buf,
> + const void *tag)
> +{
> + v4l2_buffer_set_tag(buf, (__u64)tag);
> +}
> +
> +static inline __u64 v4l2_buffer_get_tag(const struct v4l2_buffer *buf)
> +{
> + if (!(buf->flags & V4L2_BUF_FLAG_TAG))
> + return 0;
> + return (((__u64)buf->tag.high) << 32) | (__u64)buf->tag.low;
> +}
> +
> +static inline void *v4l2_buffer_get_tag_ptr(const struct v4l2_buffer *buf)
> +{
> + return (void *)v4l2_buffer_get_tag(buf);
> +}
> +
> /**
> * struct v4l2_exportbuffer - export of video buffer as DMABUF file descriptor
> *
--
Paul Kocialkowski, Bootlin (formerly Free Electrons)
Embedded Linux and kernel engineering
https://bootlin.com
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