[PATCH v2 0/6] docs: i2c: summary: update and use inclusive wording

[PATCH v2 0/6] docs: i2c: summary: update and use inclusive wording

[Wolfram Sang]

The main motivation for this series is patch 4: switching to
"controller/master" when defining the I2C terminology. This sets the
base for further improvements to inclusive language within the Linux
Kernel. The other patches are improvements found on the way.

Changes since v1:
* patch 5 added explaining 'remote' and 'local' targets
* added tags from Easwar to patches 1-3
* rebased to 6.10-rc3


Wolfram Sang (6):
  docs: i2c: summary: start sentences consistently.
  docs: i2c: summary: update I2C specification link
  docs: i2c: summary: update speed mode description
  docs: i2c: summary: document use of inclusive language
  docs: i2c: summary: document 'local' and 'remote' targets
  docs: i2c: summary: rephrase paragraph explaining the figure

 Documentation/i2c/i2c_bus.svg | 15 +++++----
 Documentation/i2c/summary.rst | 62 +++++++++++++++++++++--------------
 2 files changed, 46 insertions(+), 31 deletions(-)

-- 
2.43.0

[PATCH v2 1/6] docs: i2c: summary: start sentences consistently.

[Wolfram Sang]

Change the first paragraphs to contain only one space after the end of
the previous sentence like in the rest of the document.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Easwar Hariharan <eahariha@linux.microsoft.com>
---
 Documentation/i2c/summary.rst | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/Documentation/i2c/summary.rst b/Documentation/i2c/summary.rst
index 786c618ba3be..28ff80a2302b 100644
--- a/Documentation/i2c/summary.rst
+++ b/Documentation/i2c/summary.rst
@@ -4,10 +4,10 @@ Introduction to I2C and SMBus
 
 I²C (pronounce: I squared C and written I2C in the kernel documentation) is
 a protocol developed by Philips. It is a slow two-wire protocol (variable
-speed, up to 400 kHz), with a high speed extension (3.4 MHz).  It provides
+speed, up to 400 kHz), with a high speed extension (3.4 MHz). It provides
 an inexpensive bus for connecting many types of devices with infrequent or
-low bandwidth communications needs.  I2C is widely used with embedded
-systems.  Some systems use variants that don't meet branding requirements,
+low bandwidth communications needs. I2C is widely used with embedded
+systems. Some systems use variants that don't meet branding requirements,
 and so are not advertised as being I2C but come under different names,
 e.g. TWI (Two Wire Interface), IIC.
 
@@ -18,14 +18,14 @@ access the PDF. An older version of the specification (revision 6) is archived
 `here <https://web.archive.org/web/20210813122132/https://www.nxp.com/docs/en/user-guide/UM10204.pdf>`_.
 
 SMBus (System Management Bus) is based on the I2C protocol, and is mostly
-a subset of I2C protocols and signaling.  Many I2C devices will work on an
+a subset of I2C protocols and signaling. Many I2C devices will work on an
 SMBus, but some SMBus protocols add semantics beyond what is required to
-achieve I2C branding.  Modern PC mainboards rely on SMBus.  The most common
+achieve I2C branding. Modern PC mainboards rely on SMBus. The most common
 devices connected through SMBus are RAM modules configured using I2C EEPROMs,
 and hardware monitoring chips.
 
 Because the SMBus is mostly a subset of the generalized I2C bus, we can
-use its protocols on many I2C systems.  However, there are systems that don't
+use its protocols on many I2C systems. However, there are systems that don't
 meet both SMBus and I2C electrical constraints; and others which can't
 implement all the common SMBus protocol semantics or messages.
 
-- 
2.43.0

[PATCH v2 2/6] docs: i2c: summary: update I2C specification link

[Wolfram Sang]

Luckily, the specs are directly downloadable again, so update the link.
Also update its title to the original name "I²C".

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Easwar Hariharan <eahariha@linux.microsoft.com>
---
 Documentation/i2c/summary.rst | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/Documentation/i2c/summary.rst b/Documentation/i2c/summary.rst
index 28ff80a2302b..e3ab1d414014 100644
--- a/Documentation/i2c/summary.rst
+++ b/Documentation/i2c/summary.rst
@@ -11,11 +11,9 @@ systems. Some systems use variants that don't meet branding requirements,
 and so are not advertised as being I2C but come under different names,
 e.g. TWI (Two Wire Interface), IIC.
 
-The latest official I2C specification is the `"I2C-bus specification and user
-manual" (UM10204) <https://www.nxp.com/webapp/Download?colCode=UM10204>`_
-published by NXP Semiconductors. However, you need to log-in to the site to
-access the PDF. An older version of the specification (revision 6) is archived
-`here <https://web.archive.org/web/20210813122132/https://www.nxp.com/docs/en/user-guide/UM10204.pdf>`_.
+The latest official I2C specification is the `"I²C-bus specification and user
+manual" (UM10204) <https://www.nxp.com/docs/en/user-guide/UM10204.pdf>`_
+published by NXP Semiconductors, version 7 as of this writing.
 
 SMBus (System Management Bus) is based on the I2C protocol, and is mostly
 a subset of I2C protocols and signaling. Many I2C devices will work on an
-- 
2.43.0

[PATCH v2 3/6] docs: i2c: summary: update speed mode description

[Wolfram Sang]

Fastest I2C mode is 5 MHz. Update the docs and reword the paragraph
slightly.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Easwar Hariharan <eahariha@linux.microsoft.com>
---
 Documentation/i2c/summary.rst | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/i2c/summary.rst b/Documentation/i2c/summary.rst
index e3ab1d414014..a1e5c0715f8b 100644
--- a/Documentation/i2c/summary.rst
+++ b/Documentation/i2c/summary.rst
@@ -3,8 +3,8 @@ Introduction to I2C and SMBus
 =============================
 
 I²C (pronounce: I squared C and written I2C in the kernel documentation) is
-a protocol developed by Philips. It is a slow two-wire protocol (variable
-speed, up to 400 kHz), with a high speed extension (3.4 MHz). It provides
+a protocol developed by Philips. It is a two-wire protocol with variable
+speed (typically up to 400 kHz, high speed modes up to 5 MHz). It provides
 an inexpensive bus for connecting many types of devices with infrequent or
 low bandwidth communications needs. I2C is widely used with embedded
 systems. Some systems use variants that don't meet branding requirements,
-- 
2.43.0

[PATCH v2 4/6] docs: i2c: summary: document use of inclusive language

[Wolfram Sang]

We now have the updated I2C specs and our own Code of Conduct, so we
have all we need to switch over to the inclusive terminology. Define
them here.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
 Documentation/i2c/i2c_bus.svg | 15 ++++++++-------
 Documentation/i2c/summary.rst | 23 +++++++++++++++++------
 2 files changed, 25 insertions(+), 13 deletions(-)

diff --git a/Documentation/i2c/i2c_bus.svg b/Documentation/i2c/i2c_bus.svg
index 3170de976373..45801de4af7d 100644
--- a/Documentation/i2c/i2c_bus.svg
+++ b/Documentation/i2c/i2c_bus.svg
@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
 <!-- Created with Inkscape (http://www.inkscape.org/) -->
+<!-- Updated to inclusive terminology by Wolfram Sang -->
 
 <svg
    xmlns:dc="http://purl.org/dc/elements/1.1/"
@@ -1120,7 +1121,7 @@
     <rect
        style="opacity:1;fill:#ffb9b9;fill-opacity:1;stroke:#f00000;stroke-width:2.8125;stroke-linecap:round;stroke-linejoin:round;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
        id="rect4424-3-2-9-7"
-       width="112.5"
+       width="134.5"
        height="113.75008"
        x="112.5"
        y="471.11221"
@@ -1133,15 +1134,15 @@
        y="521.46259"
        id="text4349"><tspan
          sodipodi:role="line"
-         x="167.5354"
+         x="178.5354"
          y="521.46259"
          style="font-size:25px;line-height:1.25;font-family:sans-serif;text-align:center;text-anchor:middle"
          id="tspan1273">I2C</tspan><tspan
          sodipodi:role="line"
-         x="167.5354"
+         x="178.5354"
          y="552.71259"
          style="font-size:25px;line-height:1.25;font-family:sans-serif;text-align:center;text-anchor:middle"
-         id="tspan1285">Master</tspan></text>
+         id="tspan1285">Controller</tspan></text>
     <rect
        style="color:#000000;clip-rule:nonzero;display:inline;overflow:visible;visibility:visible;opacity:1;isolation:auto;mix-blend-mode:normal;color-interpolation:sRGB;color-interpolation-filters:linearRGB;solid-color:#000000;solid-opacity:1;fill:#b9ffb9;fill-opacity:1;fill-rule:nonzero;stroke:#006400;stroke-width:2.8125;stroke-linecap:round;stroke-linejoin:round;stroke-miterlimit:4;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1;color-rendering:auto;image-rendering:auto;shape-rendering:auto;text-rendering:auto;enable-background:accumulate"
        id="rect4424-3-2-9-7-3-3-5-3"
@@ -1171,7 +1172,7 @@
          x="318.59131"
          y="552.08752"
          style="font-size:25.00000191px;line-height:1.25;font-family:sans-serif;text-align:center;text-anchor:middle;stroke-width:1px"
-         id="tspan1287">Slave</tspan></text>
+         id="tspan1287">Target</tspan></text>
     <path
        style="fill:none;fill-rule:evenodd;stroke:#000000;stroke-width:1.99968767;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1"
        d="m 112.49995,677.36223 c 712.50005,0 712.50005,0 712.50005,0"
@@ -1233,7 +1234,7 @@
          x="468.59131"
          y="552.08746"
          style="font-size:25.00000191px;line-height:1.25;font-family:sans-serif;text-align:center;text-anchor:middle;stroke-width:1px"
-         id="tspan1287-6">Slave</tspan></text>
+         id="tspan1287-6">Target</tspan></text>
     <rect
        style="color:#000000;clip-rule:nonzero;display:inline;overflow:visible;visibility:visible;opacity:1;isolation:auto;mix-blend-mode:normal;color-interpolation:sRGB;color-interpolation-filters:linearRGB;solid-color:#000000;solid-opacity:1;vector-effect:none;fill:#b9ffb9;fill-opacity:1;fill-rule:nonzero;stroke:#006400;stroke-width:2.8125;stroke-linecap:round;stroke-linejoin:round;stroke-miterlimit:4;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1;color-rendering:auto;image-rendering:auto;shape-rendering:auto;text-rendering:auto;enable-background:accumulate"
        id="rect4424-3-2-9-7-3-3-5-3-1"
@@ -1258,7 +1259,7 @@
          x="618.59131"
          y="552.08746"
          style="font-size:25.00000191px;line-height:1.25;font-family:sans-serif;text-align:center;text-anchor:middle;stroke-width:1px"
-         id="tspan1287-9">Slave</tspan></text>
+         id="tspan1287-9">Target</tspan></text>
     <path
        style="fill:none;fill-rule:evenodd;stroke:#000000;stroke-width:1.99968743;stroke-linecap:butt;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1;marker-end:url(#DotM)"
        d="m 150,583.61221 v 93.75"
diff --git a/Documentation/i2c/summary.rst b/Documentation/i2c/summary.rst
index a1e5c0715f8b..b10b6aaafcec 100644
--- a/Documentation/i2c/summary.rst
+++ b/Documentation/i2c/summary.rst
@@ -31,15 +31,16 @@ implement all the common SMBus protocol semantics or messages.
 Terminology
 ===========
 
-Using the terminology from the official documentation, the I2C bus connects
-one or more *master* chips and one or more *slave* chips.
+The I2C bus connects one or more *controller* chips and one or more *target*
+chips.
+
 
 .. kernel-figure::  i2c_bus.svg
-   :alt:    Simple I2C bus with one master and 3 slaves
+   :alt:    Simple I2C bus with one controller and 3 targets
 
    Simple I2C bus
 
-A **master** chip is a node that starts communications with slaves. In the
+A **controller** chip is a node that starts communications with targets. In the
 Linux kernel implementation it is called an **adapter** or bus. Adapter
 drivers are in the ``drivers/i2c/busses/`` subdirectory.
 
@@ -48,8 +49,8 @@ whole class of I2C adapters. Each specific adapter driver either depends on
 an algorithm driver in the ``drivers/i2c/algos/`` subdirectory, or includes
 its own implementation.
 
-A **slave** chip is a node that responds to communications when addressed
-by the master. In Linux it is called a **client**. Client drivers are kept
+A **target** chip is a node that responds to communications when addressed
+by the controller. In Linux it is called a **client**. Client drivers are kept
 in a directory specific to the feature they provide, for example
 ``drivers/media/gpio/`` for GPIO expanders and ``drivers/media/i2c/`` for
 video-related chips.
@@ -57,3 +58,13 @@ video-related chips.
 For the example configuration in figure, you will need a driver for your
 I2C adapter, and drivers for your I2C devices (usually one driver for each
 device).
+
+Outdated terminology
+--------------------
+
+Historically, controller was named "master" and client was named "slave". These
+terms have been obsoleted with v7 of the specification and their use is also
+discouraged by the Linux Kernel Code of Conduct. You may still find them in
+references to documentation which has not been updated. The general attitude,
+however, is to use the inclusive terms: controller and target. Work to switch
+over the Linux Kernel is on-going.
-- 
2.43.0

[PATCH v2 5/6] docs: i2c: summary: document 'local' and 'remote' targets

[Wolfram Sang]

Because Linux can be a target as well, add terminology to differentiate
between Linux being the target and Linux accessing targets.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
 Documentation/i2c/summary.rst | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/Documentation/i2c/summary.rst b/Documentation/i2c/summary.rst
index b10b6aaafcec..203f6c9b2472 100644
--- a/Documentation/i2c/summary.rst
+++ b/Documentation/i2c/summary.rst
@@ -49,11 +49,16 @@ whole class of I2C adapters. Each specific adapter driver either depends on
 an algorithm driver in the ``drivers/i2c/algos/`` subdirectory, or includes
 its own implementation.
 
-A **target** chip is a node that responds to communications when addressed
-by the controller. In Linux it is called a **client**. Client drivers are kept
-in a directory specific to the feature they provide, for example
-``drivers/media/gpio/`` for GPIO expanders and ``drivers/media/i2c/`` for
-video-related chips.
+A **target** chip is a node that responds to communications when addressed by a
+controller. In the Linux kernel implementation it is called a **client**. While
+targets are usually separate external chips, Linux can also act as a target
+(needs hardware support) and respond to another controller on the bus. This is
+then called a **local target**. In contrast, an external chip is called a
+**remote target**.
+
+Client drivers are kept in a directory specific to the feature they
+provide, for example ``drivers/media/gpio/`` for GPIO expanders and
+``drivers/media/i2c/`` for video-related chips.
 
 For the example configuration in figure, you will need a driver for your
 I2C adapter, and drivers for your I2C devices (usually one driver for each
-- 
2.43.0

[PATCH v2 6/6] docs: i2c: summary: rephrase paragraph explaining the figure

[Wolfram Sang]

Use 'controller/target' and 'adapter/client' pairs consistently.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
 Documentation/i2c/summary.rst | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Documentation/i2c/summary.rst b/Documentation/i2c/summary.rst
index 203f6c9b2472..da76c787a6c5 100644
--- a/Documentation/i2c/summary.rst
+++ b/Documentation/i2c/summary.rst
@@ -60,9 +60,9 @@ Client drivers are kept in a directory specific to the feature they
 provide, for example ``drivers/media/gpio/`` for GPIO expanders and
 ``drivers/media/i2c/`` for video-related chips.
 
-For the example configuration in figure, you will need a driver for your
-I2C adapter, and drivers for your I2C devices (usually one driver for each
-device).
+For the example configuration in the figure above, you will need one adapter
+driver for the I2C controller, and client drivers for your I2C targets. Usually
+one driver for each client.
 
 Outdated terminology
 --------------------
-- 
2.43.0

Re: [PATCH v2 4/6] docs: i2c: summary: document use of inclusive language

[Easwar Hariharan]

On 6/10/2024 1:10 AM, Wolfram Sang wrote:
> We now have the updated I2C specs and our own Code of Conduct, so we
> have all we need to switch over to the inclusive terminology. Define
> them here.
> 
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> ---
>  Documentation/i2c/i2c_bus.svg | 15 ++++++++-------
>  Documentation/i2c/summary.rst | 23 +++++++++++++++++------
>  2 files changed, 25 insertions(+), 13 deletions(-)
> 

<snip>

> diff --git a/Documentation/i2c/summary.rst b/Documentation/i2c/summary.rst
> index a1e5c0715f8b..b10b6aaafcec 100644
> --- a/Documentation/i2c/summary.rst
> +++ b/Documentation/i2c/summary.rst
> @@ -31,15 +31,16 @@ implement all the common SMBus protocol semantics or messages.
>  Terminology
>  ===========
>  
> -Using the terminology from the official documentation, the I2C bus connects
> -one or more *master* chips and one or more *slave* chips.
> +The I2C bus connects one or more *controller* chips and one or more *target*
> +chips.
> +
>  
>  .. kernel-figure::  i2c_bus.svg
> -   :alt:    Simple I2C bus with one master and 3 slaves
> +   :alt:    Simple I2C bus with one controller and 3 targets
>  
>     Simple I2C bus
>  
> -A **master** chip is a node that starts communications with slaves. In the
> +A **controller** chip is a node that starts communications with targets. In the
>  Linux kernel implementation it is called an **adapter** or bus. Adapter
>  drivers are in the ``drivers/i2c/busses/`` subdirectory.
>  
> @@ -48,8 +49,8 @@ whole class of I2C adapters. Each specific adapter driver either depends on
>  an algorithm driver in the ``drivers/i2c/algos/`` subdirectory, or includes
>  its own implementation.
>  
> -A **slave** chip is a node that responds to communications when addressed
> -by the master. In Linux it is called a **client**. Client drivers are kept
> +A **target** chip is a node that responds to communications when addressed
> +by the controller. In Linux it is called a **client**. Client drivers are kept

<snip>

> +
> +Outdated terminology
> +--------------------
> +
> +Historically, controller was named "master" and client was named "slave". These
> +terms have been obsoleted with v7 of the specification and their use is also
> +discouraged by the Linux Kernel Code of Conduct. You may still find them in
> +references to documentation which has not been updated. The general attitude,
> +however, is to use the inclusive terms: controller and target. Work to switch
> +over the Linux Kernel is on-going.

What's the combined effect of this documentation update in terms of the
recommendation for switching over the Linux kernel? Are we to use
controller/client or controller/target?

Confused,
Easwar

Re: [PATCH v2 4/6] docs: i2c: summary: document use of inclusive language

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 500 bytes --]

Hi Easwar,

> What's the combined effect of this documentation update in terms of the
> recommendation for switching over the Linux kernel? Are we to use
> controller/client or controller/target?

I am not sure I understand the question properly?

"controller/target" as in the specs, and "adapter/client" when it comes
to the Linux implementation (which has been like this forever). I'd
think it is too much churn to change this as well.

> Confused,

Heh, me too now...

All the best,

   Wolfram


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Re: [PATCH v2 4/6] docs: i2c: summary: document use of inclusive language

[Easwar Hariharan]

On 6/10/2024 1:29 PM, Wolfram Sang wrote:
> Hi Easwar,
> 
>> What's the combined effect of this documentation update in terms of the
>> recommendation for switching over the Linux kernel? Are we to use
>> controller/client or controller/target?
> 
> I am not sure I understand the question properly?
> 
> "controller/target" as in the specs, and "adapter/client" when it comes
> to the Linux implementation (which has been like this forever). I'd
> think it is too much churn to change this as well.
> 
>> Confused,
> 
> Heh, me too now...
> 
> All the best,
> 
>    Wolfram

I am wondering what the impact of this doc update is on my series[1]. I
am looking for a straightforward recommendation for what terminology I,
and hopefully others, should adopt *outside the i2c subsystem*, where
Linux (typically) has a driver for the controller and is communicating
with an unknown OS/firmware on the target.

a) Spec-compliant "controller/target"
b) Linux implementation/spec hybrid "controller/client", or
c) Linux implementation "adapter/client"

I prefer (a), FWIW, so do apparently reviewers on my series.

Thanks,
Easwar

[1]
https://lore.kernel.org/all/20240508234342.2927398-1-eahariha@linux.microsoft.com/

Re: [PATCH v2 4/6] docs: i2c: summary: document use of inclusive language

[Wolfram Sang]

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> I am wondering what the impact of this doc update is on my series[1]. I
> am looking for a straightforward recommendation for what terminology I,
> and hopefully others, should adopt *outside the i2c subsystem*, where
> Linux (typically) has a driver for the controller and is communicating
> with an unknown OS/firmware on the target.
> 
> a) Spec-compliant "controller/target"
> b) Linux implementation/spec hybrid "controller/client", or
> c) Linux implementation "adapter/client"
> 
> I prefer (a), FWIW, so do apparently reviewers on my series.

I also prefer (a), but people should know what (c) means when they look
around in the kernel source. I'll see how it goes with rewording this
patch accordingly.


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Re: [PATCH v2 4/6] docs: i2c: summary: document use of inclusive language

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 511 bytes --]


> > +Outdated terminology
> > +--------------------
> > +
> > +Historically, controller was named "master" and client was named "slave". These

Ahhh, while reworking the series I finally saw that I wrote "client" in
the line above. That was an oversight, it should have been "target", of
course. Next time, please quote directly below the errornous line, that
makes it easier for me to understand what we are talking about.

Nonetheless, the rework is not in vain. I think the texts have gotten a
tad better.


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Re: [PATCH v2 5/6] docs: i2c: summary: document 'local' and 'remote' targets

[Wolfram Sang]

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> -``drivers/media/gpio/`` for GPIO expanders and ``drivers/media/i2c/`` for

Heh, for four years, nobody (including me) noticed that there is no
'drivers/media/gpio' directory...


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Re: [PATCH v2 4/6] docs: i2c: summary: document use of inclusive language

[Easwar Hariharan]

On 6/13/2024 12:52 PM, Wolfram Sang wrote:
> 
>>> +Outdated terminology
>>> +--------------------
>>> +
>>> +Historically, controller was named "master" and client was named "slave". These
> 
> Ahhh, while reworking the series I finally saw that I wrote "client" in
> the line above. That was an oversight, it should have been "target", of
> course. Next time, please quote directly below the errornous line, that
> makes it easier for me to understand what we are talking about.
> 
> Nonetheless, the rework is not in vain. I think the texts have gotten a
> tad better.
> 

Apologies, but that one word wasn't the cause of the confusion. It was:

a) "In Linux it is called a **client**", combined with
b) "The general attitude, however, is to use the inclusive terms:
controller and target. Work to switch over the Linux Kernel is on-going."

I'll try to quote better in the future.

Hope that helps,
Easwar