media: uapi: mpeg2: Split sequence and picture parameters

Typically, bitstreams are composed of a sequence header,
followed by a number of picture header and picture coding extension
headers. Each picture can be composed of a number of slices.

Let's split the MPEG-2 uAPI to follow these semantics more closely,
allowing more usage flexibility. Having these controls split up
allows applications to set a sequence control at the beginning
of a sequence, and then set a picture control for each frame.

While here add padding fields where needed, and document
the uAPI header thoroughly.

Note that the V4L2_CTRL_TYPE_{} defines had to be moved because
it clashes with existing ones. This is not really an issue
since they will be re-defined when the controls are moved
out of staging.

Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Tested-by: Jonas Karlman <jonas@kwiboo.se>
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>

4 files changed, 59 insertions, 24 deletions

diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
index aa11346e7e27..f96a2dcb22cc 100644
--- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
+++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
@@ -1636,14 +1636,6 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
     * - __u32
       - ``data_bit_offset``
       - Offset (in bits) to the video data in the current slice data.
-    * - struct :c:type:`v4l2_mpeg2_sequence`
-      - ``sequence``
-      - Structure with MPEG-2 sequence metadata, merging relevant fields from
-	the sequence header and sequence extension parts of the bitstream.
-    * - struct :c:type:`v4l2_mpeg2_picture`
-      - ``picture``
-      - Structure with MPEG-2 picture metadata, merging relevant fields from
-	the picture header and picture coding extension parts of the bitstream.
     * - __u64
       - ``backward_ref_ts``
       - Timestamp of the V4L2 capture buffer to use as backward reference, used
@@ -1661,14 +1653,28 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
     * - __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.
 
-.. c:type:: v4l2_mpeg2_sequence
+``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
+    elements from the sequence header and sequence extension parts of the
+    bitstream as specified by :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_sequence
 
 .. cssclass:: longtable
 
 .. tabularcolumns:: |p{1.4cm}|p{6.5cm}|p{9.4cm}|
 
-.. flat-table:: struct v4l2_mpeg2_sequence
+.. flat-table:: struct v4l2_ctrl_mpeg2_sequence
     :header-rows:  0
     :stub-columns: 0
     :widths:       1 1 2
@@ -1690,7 +1696,7 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
     * - __u8
       - ``chroma_format``
       - The chrominance sub-sampling format (1: 4:2:0, 2: 4:2:2, 3: 4:4:4).
-    * - __u32
+    * - __u8
       - ``flags``
       - See :ref:`MPEG-2 Sequence Flags <mpeg2_sequence_flags>`.
 
@@ -1706,11 +1712,22 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
     :widths:       1 1 2
 
     * - ``V4L2_MPEG2_SEQ_FLAG_PROGRESSIVE``
-      - 0x00000001
+      - 0x01
       - Indication that all the frames for the sequence are progressive instead
 	of interlaced.
 
-.. c:type:: v4l2_mpeg2_picture
+``V4L2_CID_MPEG_VIDEO_MPEG2_PICTURE (struct)``
+    Specifies the picture parameters (as extracted from the bitstream) for the
+    associated MPEG-2 slice data. This includes fields matching the syntax
+    elements from the picture header and picture coding extension parts of the
+    bitstream as specified by :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_picture
 
 .. raw:: latex
 
@@ -1720,30 +1737,33 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
 
 .. tabularcolumns:: |p{1.0cm}|p{5.6cm}|p{10.7cm}|
 
-.. flat-table:: struct v4l2_mpeg2_picture
+.. flat-table:: struct v4l2_ctrl_mpeg2_picture
     :header-rows:  0
     :stub-columns: 0
     :widths:       1 1 2
 
+    * - __u32
+      - ``flags``
+      - See :ref:`MPEG-2 Picture Flags <mpeg2_picture_flags>`.
+    * - __u8
+      - ``f_code[2][2]``
+      - Motion vector codes.
     * - __u8
       - ``picture_coding_type``
       - Picture coding type for the frame covered by the current slice
 	(V4L2_MPEG2_PICTURE_CODING_TYPE_I, V4L2_MPEG2_PICTURE_CODING_TYPE_P or
 	V4L2_MPEG2_PICTURE_CODING_TYPE_B).
     * - __u8
-      - ``f_code[2][2]``
-      - Motion vector codes.
+      - ``picture_structure``
+      - Picture structure (1: interlaced top field, 2: interlaced bottom field,
+	3: progressive frame).
     * - __u8
       - ``intra_dc_precision``
       - Precision of Discrete Cosine transform (0: 8 bits precision,
 	1: 9 bits precision, 2: 10 bits precision, 3: 11 bits precision).
     * - __u8
-      - ``picture_structure``
-      - Picture structure (1: interlaced top field, 2: interlaced bottom field,
-	3: progressive frame).
-    * - __u32
-      - ``flags``
-      - See :ref:`MPEG-2 Picture Flags <mpeg2_picture_flags>`.
+      - ``reserved[5]``
+      - Applications and drivers must set this to zero.
 
 
 .. _mpeg2_picture_flags:
diff --git a/Documentation/userspace-api/media/v4l/pixfmt-compressed.rst b/Documentation/userspace-api/media/v4l/pixfmt-compressed.rst
index cba607f789f0..bbbacbd65d6f 100644
--- a/Documentation/userspace-api/media/v4l/pixfmt-compressed.rst
+++ b/Documentation/userspace-api/media/v4l/pixfmt-compressed.rst
@@ -114,8 +114,9 @@ Compressed Formats
 	This format is adapted for stateless video decoders that implement a
 	MPEG-2 pipeline (using the :ref:`mem2mem` and :ref:`media-request-api`).
 	Metadata associated with the frame to decode is required to be passed
-	through the ``V4L2_CID_MPEG_VIDEO_MPEG2_SLICE_PARAMS`` control and
-	quantisation matrices can optionally be specified through the
+	through the ``V4L2_CID_MPEG_VIDEO_MPEG2_SEQUENCE``,
+        ``V4L2_CID_MPEG_VIDEO_MPEG2_PICTURE``, and ``V4L2_CID_MPEG_VIDEO_MPEG2_SLICE_PARAMS``
+        controls. Quantisation matrices can optionally be specified through the
 	``V4L2_CID_MPEG_VIDEO_MPEG2_QUANTISATION`` control.
 	See the :ref:`associated Codec Control IDs <v4l2-mpeg-mpeg2>`.
 	Exactly one output and one capture buffer must be provided for use with
diff --git a/Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst b/Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst
index 4362945fd39b..afc1505a3a7e 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst
@@ -429,6 +429,18 @@ See also the examples in :ref:`control`.
       - n/a
       - A struct :c:type:`v4l2_ctrl_mpeg2_quantisation`, containing MPEG-2
 	quantisation matrices for stateless video decoders.
+    * - ``V4L2_CTRL_TYPE_MPEG2_SEQUENCE``
+      - n/a
+      - n/a
+      - n/a
+      - A struct :c:type:`v4l2_ctrl_mpeg2_sequence`, containing MPEG-2
+	sequence parameters for stateless video decoders.
+    * - ``V4L2_CTRL_TYPE_MPEG2_PICTURE``
+      - n/a
+      - n/a
+      - n/a
+      - A struct :c:type:`v4l2_ctrl_mpeg2_picture`, containing MPEG-2
+	picture parameters for stateless video decoders.
     * - ``V4L2_CTRL_TYPE_AREA``
       - n/a
       - n/a
diff --git a/Documentation/userspace-api/media/videodev2.h.rst.exceptions b/Documentation/userspace-api/media/videodev2.h.rst.exceptions
index 5b2ebaa35d24..928fdc419ee3 100644
--- a/Documentation/userspace-api/media/videodev2.h.rst.exceptions
+++ b/Documentation/userspace-api/media/videodev2.h.rst.exceptions
@@ -134,6 +134,8 @@ replace symbol V4L2_CTRL_TYPE_STRING :c:type:`v4l2_ctrl_type`
 replace symbol V4L2_CTRL_TYPE_U16 :c:type:`v4l2_ctrl_type`
 replace symbol V4L2_CTRL_TYPE_U32 :c:type:`v4l2_ctrl_type`
 replace symbol V4L2_CTRL_TYPE_U8 :c:type:`v4l2_ctrl_type`
+replace symbol V4L2_CTRL_TYPE_MPEG2_SEQUENCE :c:type:`v4l2_ctrl_type`
+replace symbol V4L2_CTRL_TYPE_MPEG2_PICTURE :c:type:`v4l2_ctrl_type`
 replace symbol V4L2_CTRL_TYPE_MPEG2_SLICE_PARAMS :c:type:`v4l2_ctrl_type`
 replace symbol V4L2_CTRL_TYPE_MPEG2_QUANTISATION :c:type:`v4l2_ctrl_type`
 replace symbol V4L2_CTRL_TYPE_H264_SPS :c:type:`v4l2_ctrl_type`