media: docs: uAPI: fix table output in LaTeX/PDF format

There are lots of tables that are not properly displayed
in LaTeX/PDF.

Fix the tablecolumns, add longtable where needed and LaTeX
formatting macros, in order to address such issues.

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

media: v4l2: add support for colorspace conversion API (CSC) for video capture

For video capture it is the driver that reports the colorspace,
transfer function, Y'CbCr/HSV encoding and quantization range
used by the video, and there is no way to request something
different, even though many HDTV receivers have some sort of
colorspace conversion capabilities.

For output video this feature already exists since the application
specifies this information for the video format it will send out, and
the transmitter will enable any available CSC if a format conversion has
to be performed in order to match the capabilities of the sink.

For video capture we propose adding new v4l2_pix_format flag:
V4L2_PIX_FMT_FLAG_SET_CSC. The flag is set by the application,
the driver will interpret the colorspace, xfer_func, ycbcr_enc/hsv_enc
and quantization fields as the requested colorspace information and will
attempt to do the conversion it supports.

Drivers set the flags
V4L2_FMT_FLAG_CSC_COLORSPACE,
V4L2_FMT_FLAG_CSC_XFER_FUNC,
V4L2_FMT_FLAG_CSC_YCBCR_ENC/V4L2_FMT_FLAG_CSC_HSV_ENC,
V4L2_FMT_FLAG_CSC_QUANTIZATION,
in the flags field of the struct v4l2_fmtdesc during enumeration to
indicate that they support colorspace conversion for the respective field.

Drivers do not have to actually look at the flags. If the flags are not
set, then the fields 'colorspace', 'xfer_func', 'ycbcr_enc/hsv_enc',
and 'quantization' are set to the default values by the core, i.e. just
pass on the received format without conversion.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

media: docs: use the new SPDX header for GFDL-1.1 on *.rst files

SPDX v3.10 gained support for GFDL-1.1 with no invariant sections:

https://spdx.org/licenses/GFDL-1.1-no-invariants-or-later.html

So, remove the license text, replacing them by this new SPDX
license.

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

media: Documentation: v4l: move table of v4l2_pix_format(_mplane) flags to pixfmt-v4l2.rst

The table of the flags of the structs
v4l2_pix_format(_mplane) is currently in pixfmt-reserved.rst
which is wrong, it should be in pixfmt-v4l2.rst

Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

media: docs-rst: Document memory-to-memory video encoder interface

Due to complexity of the video encoding process, the V4L2 drivers of
stateful encoder hardware require specific sequences of V4L2 API calls
to be followed. These include capability enumeration, initialization,
encoding, encode parameters change, drain and reset.

Specifics of the above have been discussed during Media Workshops at
LinuxCon Europe 2012 in Barcelona and then later Embedded Linux
Conference Europe 2014 in Düsseldorf. The de facto Codec API that
originated at those events was later implemented by the drivers we already
have merged in mainline, such as s5p-mfc or coda.

The only thing missing was the real specification included as a part of
Linux Media documentation. Fix it now and document the encoder part of
the Codec API.

Signed-off-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reviewed-by: Michael Tretter <m.tretter@pengutronix.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

media: docs: move uAPI book to userspace-api/media

Since 2017, there is an space reserved for userspace API,
created by changeset 1d596dee3862 ("docs: Create a user-space API guide").

As the media subsystem was one of the first subsystems to use
Sphinx, until this patch, we were keeping things on a separate
place.

Let's just use the new location, as having all uAPI altogether
will likely make things easier for developers.

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