media: Documentation: media: Improve camera sensor documentation

Modernise the documentation to make it more precise and update the use of
pixel rate control and various other changes. In particular:

- Use non-proportional font for file names, properties as well as
  controls.

- The unit of the HBLANK control is pixels, not lines.

- The unit of PIXEL_RATE control is pixels per second, not Hz.

- Merge common requirements for CSI-2 and parallel busses.

- Include all DT properties needed for assigned clocks.

- Fix referencing the link rate control.

- SMIA driver's new name is CCS driver.

- The PIXEL_RATE control denotes pixel rate on the pixel array on camera
  sensors. Do not suggest it is used to tell the maximum pixel rate on the
  bus anymore.

- Improve ReST syntax (plain struct and function names).

- Remove the suggestion to use s_power() in receiver drivers.

- Make MIPI website URL use HTTPS, add Wikipedia links to BT.601 and
  BT.656.

Fixes: e4cf8c58af75 ("media: Documentation: media: Document how to write camera sensor drivers")
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Andrey Konovalov <andrey.konovalov@linaro.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

1 files changed, 0 insertions, 94 deletions

diff --git a/Documentation/driver-api/media/csi2.rst b/Documentation/driver-api/media/csi2.rst
deleted file mode 100644
index 11c52b0be8b8..000000000000
--- a/Documentation/driver-api/media/csi2.rst
+++ /dev/null
@@ -1,94 +0,0 @@
-.. SPDX-License-Identifier: GPL-2.0
-
-.. _MIPI_CSI_2:
-
-MIPI CSI-2
-==========
-
-CSI-2 is a data bus intended for transferring images from cameras to
-the host SoC. It is defined by the `MIPI alliance`_.
-
-.. _`MIPI alliance`: http://www.mipi.org/
-
-Media bus formats
------------------
-
-See :ref:`v4l2-mbus-pixelcode` for details on which media bus formats should
-be used for CSI-2 interfaces.
-
-Transmitter drivers
--------------------
-
-CSI-2 transmitter, such as a sensor or a TV tuner, drivers need to
-provide the CSI-2 receiver with information on the CSI-2 bus
-configuration. These include the V4L2_CID_LINK_FREQ and
-V4L2_CID_PIXEL_RATE controls and
-(:c:type:`v4l2_subdev_video_ops`->s_stream() callback). These
-interface elements must be present on the sub-device represents the
-CSI-2 transmitter.
-
-The V4L2_CID_LINK_FREQ control is used to tell the receiver driver the
-frequency (and not the symbol rate) of the link. The V4L2_CID_PIXEL_RATE
-control may be used by the receiver to obtain the pixel rate the transmitter
-uses. The :c:type:`v4l2_subdev_video_ops`->s_stream() callback provides an
-ability to start and stop the stream.
-
-The value of the V4L2_CID_PIXEL_RATE is calculated as follows::
-
-	pixel_rate = link_freq * 2 * nr_of_lanes * 16 / k / bits_per_sample
-
-where
-
-.. list-table:: variables in pixel rate calculation
-   :header-rows: 1
-
-   * - variable or constant
-     - description
-   * - link_freq
-     - The value of the V4L2_CID_LINK_FREQ integer64 menu item.
-   * - nr_of_lanes
-     - Number of data lanes used on the CSI-2 link. This can
-       be obtained from the OF endpoint configuration.
-   * - 2
-     - Two bits are transferred per clock cycle per lane.
-   * - bits_per_sample
-     - Number of bits per sample.
-   * - k
-     - 16 for D-PHY and 7 for C-PHY
-
-The transmitter drivers must, if possible, configure the CSI-2
-transmitter to *LP-11 mode* whenever the transmitter is powered on but
-not active, and maintain *LP-11 mode* until stream on. Only at stream
-on should the transmitter activate the clock on the clock lane and
-transition to *HS mode*.
-
-Some transmitters do this automatically but some have to be explicitly
-programmed to do so, and some are unable to do so altogether due to
-hardware constraints.
-
-Stopping the transmitter
-^^^^^^^^^^^^^^^^^^^^^^^^
-
-A transmitter stops sending the stream of images as a result of
-calling the ``.s_stream()`` callback. Some transmitters may stop the
-stream at a frame boundary whereas others stop immediately,
-effectively leaving the current frame unfinished. The receiver driver
-should not make assumptions either way, but function properly in both
-cases.
-
-Receiver drivers
-----------------
-
-Before the receiver driver may enable the CSI-2 transmitter by using
-the :c:type:`v4l2_subdev_video_ops`->s_stream(), it must have powered
-the transmitter up by using the
-:c:type:`v4l2_subdev_core_ops`->s_power() callback. This may take
-place either indirectly by using :c:func:`v4l2_pipeline_pm_get` or
-directly.
-
-Formats
--------
-
-The media bus pixel codes document parallel formats. Should the pixel data be
-transported over a serial bus, the media bus pixel code that describes a
-parallel format that transfers a sample on a single clock cycle is used.