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    Subject[PATCH v5 07/20] media: v4l2: Reorder field reflist
    Date
    As per spec, the field reflist requires interleaving top and bottom
    field in a specific way that does not fit inside the sort operation.
    The process consist of alternating references parity, starting with
    a reference of the same parity as the current picture. This
    processs is done twice, once for short term references and a second
    time for the long term references.

    Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
    Reviewed-by: Sebastian Fricke <sebastian.fricke@collabora.com>
    Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
    ---
    drivers/media/v4l2-core/v4l2-h264.c | 42 +++++++++++++++++++++++++++++
    1 file changed, 42 insertions(+)

    diff --git a/drivers/media/v4l2-core/v4l2-h264.c b/drivers/media/v4l2-core/v4l2-h264.c
    index fe215035d9e8..72bd64f65198 100644
    --- a/drivers/media/v4l2-core/v4l2-h264.c
    +++ b/drivers/media/v4l2-core/v4l2-h264.c
    @@ -250,6 +250,40 @@ static int v4l2_h264_b1_ref_list_cmp(const void *ptra, const void *ptrb,
    return poca < pocb ? -1 : 1;
    }

    +/*
    + * The references need to be reordered so that references are alternating
    + * between top and bottom field references starting with the current picture
    + * parity. This has to be done for short term and long term references
    + * separately.
    + */
    +static void reorder_field_reflist(const struct v4l2_h264_reflist_builder *b,
    + struct v4l2_h264_reference *reflist)
    +{
    + struct v4l2_h264_reference tmplist[V4L2_H264_REF_LIST_LEN];
    + u8 lt, i = 0, j = 0, k = 0;
    +
    + memcpy(tmplist, reflist, sizeof(tmplist[0]) * b->num_valid);
    +
    + for (lt = 0; lt <= 1; lt++) {
    + do {
    + for (; i < b->num_valid && b->refs[tmplist[i].index].longterm == lt; i++) {
    + if (tmplist[i].fields == b->cur_pic_fields) {
    + reflist[k++] = tmplist[i++];
    + break;
    + }
    + }
    +
    + for (; j < b->num_valid && b->refs[tmplist[j].index].longterm == lt; j++) {
    + if (tmplist[j].fields != b->cur_pic_fields) {
    + reflist[k++] = tmplist[j++];
    + break;
    + }
    + }
    + } while ((i < b->num_valid && b->refs[tmplist[i].index].longterm == lt) ||
    + (j < b->num_valid && b->refs[tmplist[j].index].longterm == lt));
    + }
    +}
    +
    static char ref_type_to_char(u8 ref_type)
    {
    switch (ref_type) {
    @@ -360,6 +394,9 @@ v4l2_h264_build_p_ref_list(const struct v4l2_h264_reflist_builder *builder,
    sort_r(reflist, builder->num_valid, sizeof(*reflist),
    v4l2_h264_p_ref_list_cmp, NULL, builder);

    + if (builder->cur_pic_fields != V4L2_H264_FRAME_REF)
    + reorder_field_reflist(builder, reflist);
    +
    print_ref_list_p(builder, reflist);
    }
    EXPORT_SYMBOL_GPL(v4l2_h264_build_p_ref_list);
    @@ -393,6 +430,11 @@ v4l2_h264_build_b_ref_lists(const struct v4l2_h264_reflist_builder *builder,
    sort_r(b1_reflist, builder->num_valid, sizeof(*b1_reflist),
    v4l2_h264_b1_ref_list_cmp, NULL, builder);

    + if (builder->cur_pic_fields != V4L2_H264_FRAME_REF) {
    + reorder_field_reflist(builder, b0_reflist);
    + reorder_field_reflist(builder, b1_reflist);
    + }
    +
    if (builder->num_valid > 1 &&
    !memcmp(b1_reflist, b0_reflist, builder->num_valid))
    swap(b1_reflist[0], b1_reflist[1]);
    --
    2.34.3
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