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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:02:30 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:02:30 +0000
commit76cb841cb886eef6b3bee341a2266c76578724ad (patch)
treef5892e5ba6cc11949952a6ce4ecbe6d516d6ce58 /Documentation/hwmon/submitting-patches
parentInitial commit. (diff)
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Adding upstream version 4.19.249.upstream/4.19.249upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+ How to Get Your Patch Accepted Into the Hwmon Subsystem
+ -------------------------------------------------------
+
+This text is a collection of suggestions for people writing patches or
+drivers for the hwmon subsystem. Following these suggestions will greatly
+increase the chances of your change being accepted.
+
+
+1. General
+----------
+
+* It should be unnecessary to mention, but please read and follow
+ Documentation/process/submit-checklist.rst
+ Documentation/process/submitting-drivers.rst
+ Documentation/process/submitting-patches.rst
+ Documentation/process/coding-style.rst
+
+* Please run your patch through 'checkpatch --strict'. There should be no
+ errors, no warnings, and few if any check messages. If there are any
+ messages, please be prepared to explain.
+
+* If your patch generates checkpatch errors, warnings, or check messages,
+ please refrain from explanations such as "I prefer that coding style".
+ Keep in mind that each unnecessary message helps hiding a real problem,
+ and a consistent coding style makes it easier for others to understand
+ and review the code.
+
+* Please test your patch thoroughly. We are not your test group.
+ Sometimes a patch can not or not completely be tested because of missing
+ hardware. In such cases, you should test-build the code on at least one
+ architecture. If run-time testing was not achieved, it should be written
+ explicitly below the patch header.
+
+* If your patch (or the driver) is affected by configuration options such as
+ CONFIG_SMP, make sure it compiles for all configuration variants.
+
+
+2. Adding functionality to existing drivers
+-------------------------------------------
+
+* Make sure the documentation in Documentation/hwmon/<driver_name> is up to
+ date.
+
+* Make sure the information in Kconfig is up to date.
+
+* If the added functionality requires some cleanup or structural changes, split
+ your patch into a cleanup part and the actual addition. This makes it easier
+ to review your changes, and to bisect any resulting problems.
+
+* Never mix bug fixes, cleanup, and functional enhancements in a single patch.
+
+
+3. New drivers
+--------------
+
+* Running your patch or driver file(s) through checkpatch does not mean its
+ formatting is clean. If unsure about formatting in your new driver, run it
+ through Lindent. Lindent is not perfect, and you may have to do some minor
+ cleanup, but it is a good start.
+
+* Consider adding yourself to MAINTAINERS.
+
+* Document the driver in Documentation/hwmon/<driver_name>.
+
+* Add the driver to Kconfig and Makefile in alphabetical order.
+
+* Make sure that all dependencies are listed in Kconfig.
+
+* Please list include files in alphabetic order.
+
+* Please align continuation lines with '(' on the previous line.
+
+* Avoid forward declarations if you can. Rearrange the code if necessary.
+
+* Avoid macros to generate groups of sensor attributes. It not only confuses
+ checkpatch, but also makes it more difficult to review the code.
+
+* Avoid calculations in macros and macro-generated functions. While such macros
+ may save a line or so in the source, it obfuscates the code and makes code
+ review more difficult. It may also result in code which is more complicated
+ than necessary. Use inline functions or just regular functions instead.
+
+* Limit the number of kernel log messages. In general, your driver should not
+ generate an error message just because a runtime operation failed. Report
+ errors to user space instead, using an appropriate error code. Keep in mind
+ that kernel error log messages not only fill up the kernel log, but also are
+ printed synchronously, most likely with interrupt disabled, often to a serial
+ console. Excessive logging can seriously affect system performance.
+
+* Use devres functions whenever possible to allocate resources. For rationale
+ and supported functions, please see Documentation/driver-model/devres.txt.
+ If a function is not supported by devres, consider using devm_add_action().
+
+* If the driver has a detect function, make sure it is silent. Debug messages
+ and messages printed after a successful detection are acceptable, but it
+ must not print messages such as "Chip XXX not found/supported".
+
+ Keep in mind that the detect function will run for all drivers supporting an
+ address if a chip is detected on that address. Unnecessary messages will just
+ pollute the kernel log and not provide any value.
+
+* Provide a detect function if and only if a chip can be detected reliably.
+
+* Only the following I2C addresses shall be probed: 0x18-0x1f, 0x28-0x2f,
+ 0x48-0x4f, 0x58, 0x5c, 0x73 and 0x77. Probing other addresses is strongly
+ discouraged as it is known to cause trouble with other (non-hwmon) I2C
+ chips. If your chip lives at an address which can't be probed then the
+ device will have to be instantiated explicitly (which is always better
+ anyway.)
+
+* Avoid writing to chip registers in the detect function. If you have to write,
+ only do it after you have already gathered enough data to be certain that the
+ detection is going to be successful.
+
+ Keep in mind that the chip might not be what your driver believes it is, and
+ writing to it might cause a bad misconfiguration.
+
+* Make sure there are no race conditions in the probe function. Specifically,
+ completely initialize your chip and your driver first, then register with
+ the hwmon subsystem.
+
+* Use devm_hwmon_device_register_with_groups() or, if your driver needs a remove
+ function, hwmon_device_register_with_groups() to register your driver with the
+ hwmon subsystem. Try using devm_add_action() instead of a remove function if
+ possible. Do not use hwmon_device_register().
+
+* Your driver should be buildable as module. If not, please be prepared to
+ explain why it has to be built into the kernel.
+
+* Do not provide support for deprecated sysfs attributes.
+
+* Do not create non-standard attributes unless really needed. If you have to use
+ non-standard attributes, or you believe you do, discuss it on the mailing list
+ first. Either case, provide a detailed explanation why you need the
+ non-standard attribute(s).
+ Standard attributes are specified in Documentation/hwmon/sysfs-interface.
+
+* When deciding which sysfs attributes to support, look at the chip's
+ capabilities. While we do not expect your driver to support everything the
+ chip may offer, it should at least support all limits and alarms.
+
+* Last but not least, please check if a driver for your chip already exists
+ before starting to write a new driver. Especially for temperature sensors,
+ new chips are often variants of previously released chips. In some cases,
+ a presumably new chip may simply have been relabeled.