media: uapi: mpeg2: Remove V4L2_CID_MPEG_VIDEO_MPEG2_SLICE_PARAMS

The Hantro and Cedrus drivers work in frame-mode,
meaning they expect all the slices in a picture (either frame
or field structure) to be passed in each OUTPUT buffer.

These two are the only V4L2 MPEG-2 stateless decoders currently
supported. Given the VA-API drivers also work per-frame,
coalescing all the MPEG-2 slices in a buffer before the decoding
operation, it makes sense to not expect slice-mode drivers and
therefore remove V4L2_CID_MPEG_VIDEO_MPEG2_SLICE_PARAMS.

This is done to avoid carrying an unused interface. If needed,
this control can be added without breaking backwards compatibility.
Note that this would mean introducing a enumerator control to
specify the decoding mode (see V4L2_CID_STATELESS_H264_DECODE_MODE).

Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Co-developed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Tested-by: Jernej Skrabec <jernej.skrabec@siol.net>
Reviewed-by: Jernej Skrabec <jernej.skrabec@siol.net>
Tested-by: Daniel Almeida <daniel.almeida@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst

@@ -1608,41 +1608,6 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
 
 .. _v4l2-mpeg-mpeg2:
 
-``V4L2_CID_MPEG_VIDEO_MPEG2_SLICE_PARAMS (struct)``
-    Specifies the slice parameters (as extracted from the bitstream) for the
-    associated MPEG-2 slice data. This includes the necessary parameters for
-    configuring a stateless hardware decoding pipeline for MPEG-2.
-    The bitstream parameters are defined according to :ref:`mpeg2part2`.
-
-    .. note::
-
-       This compound control is not yet part of the public kernel API and
-       it is expected to change.
-
-.. c:type:: v4l2_ctrl_mpeg2_slice_params
-
-.. tabularcolumns:: |p{5.6cm}|p{4.6cm}|p{7.1cm}|
-
-.. cssclass:: longtable
-
-.. flat-table:: struct v4l2_ctrl_mpeg2_slice_params
-    :header-rows:  0
-    :stub-columns: 0
-    :widths:       1 1 2
-
-    * - __u32
-      - ``bit_size``
-      - Size (in bits) of the current slice data.
-    * - __u32
-      - ``data_bit_offset``
-      - Offset (in bits) to the video data in the current slice data.
-    * - __u32
-      - ``quantiser_scale_code``
-      - Code used to determine the quantization scale to use for the IDCT.
-    * - __u8
-      - ``reserved``
-      - Applications and drivers must set this to zero.
-
 ``V4L2_CID_MPEG_VIDEO_MPEG2_SEQUENCE (struct)``
     Specifies the sequence parameters (as extracted from the bitstream) for the
     associated MPEG-2 slice data. This includes fields matching the syntax