Re: [PATCH v7 1/7] media: add glossary.rst with a glossary of terms used at V4L2 spec

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On 09/28/2017 12:23 AM, 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@xxxxxxxxxxxxxxxx>
> ---
>  Documentation/media/uapi/v4l/glossary.rst | 136 ++++++++++++++++++++++++++++++
>  Documentation/media/uapi/v4l/v4l2.rst     |   1 +
>  2 files changed, 137 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..b6767da1a46e
> --- /dev/null
> +++ b/Documentation/media/uapi/v4l/glossary.rst
> @@ -0,0 +1,136 @@
> +========
> +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
> +	The same as V4L2 main driver.

Change this to the more standard phrase:

See: V4L2 main driver.

> +
> +    Device Node
> +	A character device node in the file system used to control and do

and -> and/or

> +	input/output data transfers from/to a Kernel driver.
> +
> +    Digital Signal Processor - DSP
> +	A specialized microprocessor, with its architecture optimized for
> +	the operational needs of digital signal processing.

I'd say 'requirements' instead of 'needs'. I think that's a better term.

> +
> +    Driver
> +	The part of the Linux Kernel that implements support
> +	for a hardware component.
> +
> +    Field-programmable Gate Array - FPGA
> +	A field-programmable gate array (FPGA) is an 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 media hardware. For example an I²C or SPI device,
> +	or an IP block inside an SoC or FPGA.
> +
> +    Image Signal Processor - ISP
> +	A specialised processor 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).
> +
> +    Inter-Integrated Circuit - I²C
> +	A  multi-master, multi-slave, packet switched, single-ended,
> +	serial computer bus used to control V4L2 sub-devices.

I'd rephrase this a bit:

	A  multi-master, multi-slave, packet switched, single-ended,
	serial computer bus. Most V4L2 sub-devices are controlled via
	this bus.

Your text suggested that i2c is used exclusively for V4L2 subdevs, but
of course it is used for many other devices as well.

> +
> +	See http://www.nxp.com/docs/en/user-guide/UM10204.pdf.
> +
> +    Integrated circuit - IC
> +	A set of electronic circuits on one small flat piece of
> +	semiconductor material, normally silicon.
> +
> +	Also known as chip.

Perhaps add an entry for 'Chip' as well, with a 'See: Integrated circuit' as
description? Just to be consistent.

> +
> +    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).
> +
> +    IP block
> +	The same as IP core.

'See: '

> +
> +    MC-centric
> +	V4L2 hardware that requires a Media controller.
> +
> +	See :ref:`v4l2_hardware_control`.
> +
> +    Media Controller
> +	An API designed to expose and control devices and sub-devices
> +	relationships to applications.

This sentence is not clear. I propose this:

	An API designed to expose and control the relationships of the Media
	Harware to applications.

> +
> +	See :ref:`media_controller`.
> +
> +    Media hardware
> +	A group of hardware components that together make a larger
> +	user-facing functional media hardware. For instance the SoC ISP IP

I'd just say "form the functional". The term 'user-facing' is out of place here.

> +	cores and external camera sensors together make a

make a -> form the

Possible synonym for 'form': 'constitute'. I'm OK with either.

> +	camera media hardware.
> +
> +    Media hardware control
> +	Type of control for a media hardware supported by V4L2 drivers.
> +
> +	See :ref:`v4l2_hardware_control`.
> +
> +    Microprocessor
> +	An electronic circuitry that carries out the instructions
> +	of a computer program by performing the basic arithmetic, logical,
> +	control and input/output (I/O) operations specified by the
> +	instructions on a single integrated circuit.
> +
> +    SMBus
> +	A subset of I²C, with defines a stricter usage of the bus.
> +
> +    Serial Peripheral Interface Bus - SPI
> +	Synchronous serial communication interface specification used for
> +	short distance communication, primarily in embedded systems.
> +
> +    System on a Chip - SoC
> +	An integrated circuit that integrates all components of a computer
> +	or other electronic systems.
> +
> +    V4L2 device node
> +	A device node that is associated to a V4L2 main driver,
> +	as specified in :ref:`v4l2_device_naming`.
> +
> +    V4L2 hardware
> +	A hardware used to on a media device supported by the V4L2
> +	subsystem.

No idea what you mean here. Perhaps this:

Hardware that is controlled by a V4L2 main driver or a V4L2 sub-device driver.
V4L2 hardware is a subset of the Media hardware. Often the two are the same,
but Media hardware can also contain other non-V4L2 hardware such as DVB hardware.

> +
> +    V4L2 main driver
> +	The V4L2 device driver that implements the main logic to talk with
> +	the V4L2 hardware.
> +
> +	Also known as bridge driver.
> +
> +	See :ref:`v4l2_hardware_control`.
> +
> +    V4L2 sub-device
> +	Part of the media hardware that is implemented via a
> +	V4L2 sub-device driver.

When we talk about 'V4L2 sub-device' we talk about a driver that implement
the subdev kernel API. I suggest that you change 'V4L2 sub-device' to
'V4L2 sub-device driver', then explain that such a driver implements support
for a Hardware component.

> +
> +	See :ref:`subdev`.
> +
> +    Vdevnode-centric
> +	V4L2 hardware that it is controlled via V4L2 device nodes.

'that it' -> 'that'

This also needs a reference:

	See :ref:`v4l2_hardware_control`.

> +
> +	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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