linux-kernel - [PATCH v2 2/3] Documentation/i2c: sync docs with current state of i2c-tools

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Message-Id: <20180413164405.127522-2-hansens@google.com>
Date:   Fri, 13 Apr 2018 09:44:04 -0700
From:   Sam Hansen <hansens@...gle.com>
To:     linux-i2c@...r.kernel.org, hansens@...gle.com, wsa@...-dreams.de,
        corbet@....net, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Sam Hansen <hansens@...gle.com>, wsa@...-dreams.de, corbet@....net,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 2/3] Documentation/i2c: sync docs with current state of i2c-tools

Currently, Documentation/i2c/dev-interface describes the use of
i2c_smbus_* helper routines as static inlined functions provided by
linux/i2c-dev.h.  Work has been done to refactor the linux/i2c-dev.h file
in the i2c-tools project out into its own library.  As a result, these
docs have become stale.

This patch corrects the discrepancy and directs the reader to the
i2c-tools project for more information.

Signed-off-by: Sam Hansen <hansens@...gle.com>
---
 Documentation/i2c/dev-interface | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/Documentation/i2c/dev-interface b/Documentation/i2c/dev-interface
index c8737d502791..f92ee1f59914 100644
--- a/Documentation/i2c/dev-interface
+++ b/Documentation/i2c/dev-interface
@@ -23,11 +23,6 @@ First, you need to include these two headers:
   #include <linux/i2c-dev.h>
   #include <i2c/smbus.h>
 
-(Please note that there are two files named "i2c-dev.h" out there. One is
-distributed with the Linux kernel and the other one is included in the
-source tree of i2c-tools. They used to be different in content but since 2012
-they're identical. You should use "linux/i2c-dev.h").
-
 Now, you have to decide which adapter you want to access. You should
 inspect /sys/class/i2c-dev/ or run "i2cdetect -l" to decide this.
 Adapter numbers are assigned somewhat dynamically, so you can not
@@ -140,8 +135,8 @@ ioctl(file, I2C_RDWR, struct i2c_rdwr_ioctl_data *msgset)
   set in each message, overriding the values set with the above ioctl's.
 
 ioctl(file, I2C_SMBUS, struct i2c_smbus_ioctl_data *args)
-  Not meant to be called  directly; instead, use the access functions
-  below.
+  If possible, use the provided i2c_smbus_* methods described below instead
+  of issuing direct ioctls.
 
 You can do plain i2c transactions by using read(2) and write(2) calls.
 You do not need to pass the address byte; instead, set it through
@@ -166,10 +161,9 @@ what happened. The 'write' transactions return 0 on success; the
 returns the number of values read. The block buffers need not be longer
 than 32 bytes.
 
-The above functions are all inline functions, that resolve to calls to
-the i2c_smbus_access function, that on its turn calls a specific ioctl
-with the data in a specific format. Read the source code if you
-want to know what happens behind the screens.
+The above functions are made available by linking against the libi2c library,
+which is provided by the i2c-tools project.  See:
+https://git.kernel.org/pub/scm/utils/i2c-tools/i2c-tools.git/.
 
 
 Implementation details
-- 
2.17.0.484.g0c8726318c-goog