Date:   Tue, 10 Oct 2017 15:53:46 +0200
From:   Hans Verkuil <hverkuil@...all.nl>
To:     Mauro Carvalho Chehab <mchehab@...pensource.com>,
        Linux Doc Mailing List <linux-doc@...r.kernel.org>,
        Linux Media Mailing List <linux-media@...r.kernel.org>
Cc:     Mauro Carvalho Chehab <mchehab@...radead.org>,
        linux-kernel@...r.kernel.org, Jonathan Corbet <corbet@....net>,
        Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>,
        Hans Verkuil <hans.verkuil@...co.com>
Subject: Re: [PATCH v8 1/7] media: add glossary.rst with a glossary of terms
 used at V4L2 spec

More (mostly) small stuff:

On 10/10/2017 01:45 PM, Mauro Carvalho Chehab wrote:
> Add a glossary of terms for V4L2, as several concepts are complex
> enough to cause misunderstandings.
> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab@...pensource.com>
> ---
>  Documentation/media/uapi/v4l/glossary.rst | 167 ++++++++++++++++++++++++++++++
>  Documentation/media/uapi/v4l/v4l2.rst     |   1 +
>  2 files changed, 168 insertions(+)
>  create mode 100644 Documentation/media/uapi/v4l/glossary.rst
> 
> diff --git a/Documentation/media/uapi/v4l/glossary.rst b/Documentation/media/uapi/v4l/glossary.rst
> new file mode 100644
> index 000000000000..a5a832b4dda5
> --- /dev/null
> +++ b/Documentation/media/uapi/v4l/glossary.rst
> @@ -0,0 +1,167 @@
> +========
> +Glossary
> +========
> +
> +.. note::
> +
> +   This goal of section is to standardize the terms used within the V4L2
> +   documentation. It is written incrementally as they are standardized in
> +   the V4L2 documentation. So, it is a Work In Progress.
> +
> +.. Please keep the glossary entries in alphabetical order
> +
> +.. glossary::
> +
> +    Bridge driver
> +	A driver that provides a bridge between the CPU's bus to the
> +	data and control buses of a :term:`media hardware`. Often, the
> +	bridge driver is the same as :term:`V4L2 main driver`.
> +
> +    Chip
> +	:See: :term:`Integrated circuit`.
> +
> +    Device Driver
> +    Driver
> +	The part of the Linux Kernel that implements support
> +	for a :term:`hardware component`.
> +
> +    Device Node
> +	A character device node in the file system used to control and/or
> +	do input/output data transfers from/to a Kernel driver.
> +
> +    Digital Signal Processor
> +    DSP
> +	A specialized :term:`microprocessor`, with its architecture optimized
> +	for the operational requirements of digital signal processing.
> +
> +    Field-programmable Gate Array
> +    FPGA
> +	A field-programmable gate array (FPGA) is an :term:`integrated circuit`
> +	designed to be configured by a customer or a designer after
> +	manufacturing.
> +
> +	:See: https://en.wikipedia.org/wiki/Field-programmable_gate_array.
> +
> +    Hardware component
> +	A subset of the :term:`media hardware`. For example an :term:`I²C`
> +	or :term:`SPI` device, or an :term:`IP block` inside an
> +	:term:`SoC` or :term:`FPGA`.
> +
> +    Image Signal Processor
> +    ISP
> +	A specialized :term:`microprocessor` that implements a set of
> +	algorithms for processing image data. ISPs may implement algorithms
> +	for lens shading correction, demosaic, scaling and pixel format
> +	conversion as well as produce statistics for the use of the control
> +	algorithms (e.g. automatic exposure, white balance and focus).
> +
> +	ISP drivers often contain a receiver for image data from external
> +	sources such as sensors and act as :term:`V4L2 main driver`.
> +
> +    Integrated circuit
> +    IC
> +	A set of electronic circuits on one small flat piece of
> +	semiconductor material, normally silicon.
> +
> +	Also known as :term:`chip`.
> +
> +    Intellectual property core
> +    IP core
> +	In electronic design a semiconductor intellectual property core,
> +	is a reusable unit of logic, cell, or integrated circuit layout
> +	design that is the intellectual property of one party.
> +	IP cores may be licensed to another party or can be owned
> +	and used by a single party alone.
> +
> +	:See: https://en.wikipedia.org/wiki/Semiconductor_intellectual_property_core).
> +
> +    Inter-Integrated Circuit
> +    I²C
> +	A  multi-master, multi-slave, packet switched, single-ended,
> +	serial computer bus. A :term:`V4L2 sub-device driver` usually is
> +	controlled via this bus.
> +
> +	:See: http://www.nxp.com/docs/en/user-guide/UM10204.pdf.
> +
> +    IP block
> +	:See: :term:`IP core`.
> +
> +    Media controller
> +    MC
> +	An API designed to expose and control the relationships of the
> +	:term:`media hardware` to applications.
> +
> +	:See: :ref:`media_controller`.
> +
> +    Media controller centric
> +    MC-centric
> +	:term:`V4L2 hardware` that requires a :term:`media controller`.
> +
> +	:See: :ref:`v4l2_hardware_control`.
> +
> +    Media hardware
> +	A group of hardware components that together form the
> +	functional media hardware. For instance the :term:`SoC`
> +	:term:`ISP` :term:`IP cores <ip core>` and external camera
> +	sensors together form the camera media hardware.

Perhaps this is a bit better:

	...form the media hardware for a camera.

> +
> +    Media hardware control
> +	Type of control for a :term:`media hardware` supported a

for a -> for
supported -> supported by

> +	V4L2 :term:`driver`.
> +
> +	:See: :ref:`v4l2_hardware_control`.

Do we actually need this term in the glossary? I'm not convinced. We will
typically talk about 'MC-centric' or 'Video device node centric', but rarely
about 'Media hardware control'. Just my opinion though.

> +
> +    Microprocessor
> +	An electronic circuitry that carries out the instructions

It's either "Electronic circuitry" or "An electronic circuit". In this case
I'd say the former, but I'm no HW engineer.

> +	of a computer program by performing the basic arithmetic, logical,
> +	control and input/output (I/O) operations specified by the
> +	instructions on a single :term:`integrated circuit`.
> +
> +    SMBus
> +	A subset of :term:`I²C`, with defines a stricter usage of the bus.

with -> which

> +
> +    Serial Peripheral Interface
> +    SPI
> +	Synchronous serial communication interface specification used for
> +	short distance communication, primarily in embedded systems.

...primarily used in...

> +
> +    System on a Chip
> +    SoC
> +	An :term:`integrated circuit` that integrates all components of a
> +	computer or other electronic systems.
> +
> +    V4L2 device node
> +	A :term:`device node` that is associated to a
> +	:term:`V4L2 main driver`, as specified in :ref:`v4l2_device_naming`.
> +
> +    V4L2 hardware
> +	Hardware that is controlled by a :term:`V4L2 main driver` or a
> +	:term:`V4L2 sub-device driver`. V4L2 hardware is a subset of the
> +	:term:`media hardware`. Often the two are the same, but
> +	:term:`media hardware` can also contain other non-V4L2 hardware
> +	such as Digital TV hardware.
> +
> +    V4L2 main driver
> +	The V4L2 :term:`device driver` that implements the main logic to
> +	talk with the :term:`V4L2 hardware`.
> +
> +	Often, the same as :term:`bridge driver`.

Remove the comma after 'Often'.

> +
> +	:See: :ref:`v4l2_hardware_control`.
> +
> +    V4L2 sub-device
> +	:See: :term:`V4L2 sub-device driver`.

Isn't a "V4L2 sub-device" typically an instance of a device as implemented by
a "V4L2 sub-device driver"?

> +
> +    V4L2 sub-device driver
> +	A :term:`driver` for a :term:`media hardware` whose bus(es)

Not media hardware, but "hardware component".

> +	connects it to the hardware controlled via the

I think 'by' is better than 'via'.

> +	:term:`V4L2 main driver`.
> +
> +	:See: :ref:`subdev`.
> +
> +    Video device node centric
> +    Vdevnode-centric
> +	:term:`V4L2 hardware` that is controlled via

Same as before: I think 'by' is better than 'via'.

> +	:term:`V4L2 device nodes <v4l2 device node>`.
> +
> +	:See: :ref:`v4l2_hardware_control`.
> diff --git a/Documentation/media/uapi/v4l/v4l2.rst b/Documentation/media/uapi/v4l/v4l2.rst
> index 2128717299b3..698c060939f0 100644
> --- a/Documentation/media/uapi/v4l/v4l2.rst
> +++ b/Documentation/media/uapi/v4l/v4l2.rst
> @@ -32,6 +32,7 @@ This part describes the Video for Linux API version 2 (V4L2 API) specification.
>      videodev
>      capture-example
>      v4l2grab-example
> +    glossary
>      biblio
>  
>  
> 

Regards,

	Hans

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