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.
Wolfram Sang (5):
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: rephrase paragraph explaining the figure
Documentation/i2c/i2c_bus.svg | 15 ++++++-----
Documentation/i2c/summary.rst | 51 ++++++++++++++++++++---------------
2 files changed, 38 insertions(+), 28 deletions(-)
--
2.43.0
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 <[email protected]>
---
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
Fastest I2C mode is 5 MHz. Update the docs and reword the paragraph
slightly.
Signed-off-by: Wolfram Sang <[email protected]>
---
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
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 <[email protected]>
---
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
Use 'controller/target' and 'adapter/client' pairs consistently.
Signed-off-by: Wolfram Sang <[email protected]>
---
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 b10b6aaafcec..1b5bc7ed46aa 100644
--- a/Documentation/i2c/summary.rst
+++ b/Documentation/i2c/summary.rst
@@ -55,9 +55,9 @@ 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
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 <[email protected]>
---
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
On 6/7/2024 4:17 AM, Wolfram Sang wrote:
> 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 <[email protected]>
> ---
> Documentation/i2c/summary.rst | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
Looks good to me.
Reviewed-by: Easwar Hariharan <[email protected]>
On 6/7/2024 4:17 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 <[email protected]>
> ---
> 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
Are we continuing to use client instead of local target and remote target?
Thanks,
Easwar
On 6/7/2024 4:17 AM, Wolfram Sang wrote:
> 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 <[email protected]>
> ---
> 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
Looks good to me.
Reviewed-by: Easwar Hariharan <[email protected]>
On 6/7/2024 4:17 AM, Wolfram Sang wrote:
> Fastest I2C mode is 5 MHz. Update the docs and reword the paragraph
> slightly.
>
> Signed-off-by: Wolfram Sang <[email protected]>
> ---
> 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,
Looks good to me.
Reviewed-by: Easwar Hariharan <[email protected]>
On 6/7/2024 4:17 AM, Wolfram Sang wrote:
> Use 'controller/target' and 'adapter/client' pairs consistently.
>
> Signed-off-by: Wolfram Sang <[email protected]>
> ---
> 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 b10b6aaafcec..1b5bc7ed46aa 100644
> --- a/Documentation/i2c/summary.rst
> +++ b/Documentation/i2c/summary.rst
> @@ -55,9 +55,9 @@ 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
> --------------------
Similar feedback as for patch 4. I thought we agreed on using {local,
remote} target for in-line clarity.
Thanks,
Easwar
> > +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
>
> Are we continuing to use client instead of local target and remote target?
Nope, "client" is just the Linux word for "target". Like "adapter" for
"controller". Historic legacy. So, in a way "local client" and "remote
client" would also work to emphasize the distinction.
This document so far only talks about "remote targets". I noticed this a
few hours ago and concluded that another paragraph needs to be added
explaining that Linux can be a target as well. And that this is called a
"local target" while the other ones are "remote targets".
Makes sense?