vivid_uvc_meta_buf
meta->buffersize = sizeof(struct vivid_uvc_meta_buf);
struct vivid_uvc_meta_buf *meta = vb2_plane_vaddr(&buf->vb.vb2_buf, 0);
meta->length = sizeof(*meta) - offsetof(struct vivid_uvc_meta_buf, length);
unsigned int size = sizeof(struct vivid_uvc_meta_buf);
unsigned int size = sizeof(struct vivid_uvc_meta_buf);