media: drivers/media/v4l2-core/v4l2-h264 : add detection of null pointers

When the pointer variable is judged to be null, null is returned
directly.

[hverkuil: fix two checkpatch warnings]

Signed-off-by: Dong Chuanjian <chuanjian@nfschina.com>
Acked-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Fixes: d3f756ad629b ("media: v4l2: Trace calculated p/b0/b1 initial reflist")
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

media: v4l2: Reorder field reflist

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>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

media: h264: Sort p/b reflist using frame_num

In the reference list builder, frame_num refers to FrameNumWrap
in the spec, which is the same as the pic_num for frame decoding.
The same applies for long_term_pic_num and long_term_frame_idx.

Sort all type of references by frame_num so the sort can be reused
for fields reflist were the sorting is done using frame_num instead.
In short, pic_num is never actually used for building reference
lists.

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>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

media: v4l2: Trace calculated p/b0/b1 initial reflist

Add debug print statements to print the content of P & B reference
lists, to verify that the ordering of the generated reference lists is
correct. This is especially important for the field decoding mode,
where sorting is more complex.

Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Tested-by: Sebastian Fricke <sebastian.fricke@collabora.com>
Reviewed-by: Sebastian Fricke <sebastian.fricke@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

media: h264: Store all fields into the unordered list

When the current picture is a field, store each field into the
unordered_list and preserve both top and bottom picture order
count.

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>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

media: h264: Store current picture fields

This information, also called picture structure, is required in field
decoding mode to construct reference lists.

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>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

media: h264: Increase reference lists size to 32

This is to accommodate support for field decoding, which splits the top
and the bottom references into the reference list.

Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Reviewed-by: Sebastian Fricke <sebastian.fricke@collabora.com>
Reviewed-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

media: h264: Use v4l2_h264_reference for reflist

In preparation for adding field decoding support, convert the byte arrays
for reflist into array of struct v4l2_h264_reference. That struct will
allow us to mark which field of the reference picture is being referenced.

[hverkuil: top_field_order_cnt -> pic_order_count]

Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Reviewed-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

media: h264: Avoid wrapping long_term_frame_idx

For long term references, frame_num is set to long_term_frame_idx which
does not require wrapping. This is fixed by observation, no directly
related issue have been found yet.

Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Reviewed-by: Sebastian Fricke <sebastian.fricke@collabora.com>
Reviewed-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

media: uapi: h264: Clean slice invariants syntax elements

The H.264 specification requires in section 7.4.3 "Slice header semantics",
that the following values shall be the same in all slice headers:

pic_parameter_set_id
frame_num
field_pic_flag
bottom_field_flag
idr_pic_id
pic_order_cnt_lsb
delta_pic_order_cnt_bottom
delta_pic_order_cnt[ 0 ]
delta_pic_order_cnt[ 1 ]
sp_for_switch_flag
slice_group_change_cycle

These bitstream fields are part of the slice header, and therefore
passed redundantly on each slice. The purpose of the redundancy
is to make the codec fault-tolerant in network scenarios.

This is of course not needed to be reflected in the V4L2 controls,
given the bitstream has already been parsed by applications.
Therefore, move the redundant fields to the per-frame decode
parameters control (DECODE_PARAMS).

Field 'pic_parameter_set_id' is simply removed in this case,
because the PPS control must currently contain the active PPS.

Syntax elements dec_ref_pic_marking() and those related
to pic order count, remain invariant as well, and therefore,
the fields dec_ref_pic_marking_bit_size and pic_order_cnt_bit_size
are also common to all slices.

Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Tested-by: Jonas Karlman <jonas@kwiboo.se>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

media: uapi: h264: Clean DPB entry interface

As discussed recently, the current interface for the
Decoded Picture Buffer is not enough to properly
support field coding.

This commit introduces enough semantics to support
frame and field coding, and to signal how DPB entries
are "used for reference".

Reserved fields will be added by a follow-up commit.

Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Tested-by: Jonas Karlman <jonas@kwiboo.se>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

media: v4l2-core: Add helpers to build the H264 P/B0/B1 reflists

Building those list is a standard procedure described in section
'8.2.4 Decoding process for reference picture lists construction' of
the H264 specification.

We already have 2 drivers needing the same logic (hantro and rkvdec) and
I suspect we will soon have more.

Let's provide generic helpers to create those lists.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>