media: docs: uAPI: Expand error documentation for invalid 'which' value

Multiple subdev ioctls that take a 'which' field do not document the
error returned when the field has an invalid value. Expand the
documentation to fix this.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

media: subdev: add stream based configuration

Add support to manage configurations (format, crop, compose) per stream,
instead of per pad. This is accomplished with data structures that hold
an array of all subdev's stream configurations.

The number of streams can vary at runtime based on routing. Every time
the routing is changed, the stream configurations need to be
re-initialized.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

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: docs: make V4L documents more compatible with Sphinx 3.1+

Sphinx 3.x broke support for the cdomain.py extension, as the
c domain code was rewritten. Due to that, the c tags need to
be re-written, in order to use the new c domain notation.

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: 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>