path: root/Documentation/hwmon/submitting-patches
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authorAnton Arapov <>2012-04-16 10:05:28 +0200
committerAnton Arapov <>2012-04-16 10:05:28 +0200
commitb4b6116a13633898cf868f2f103c96a90c4c20f8 (patch)
tree93d1b7e2cfcdf473d8d4ff3ad141fa864f8491f6 /Documentation/hwmon/submitting-patches
parentedd4be777c953e5faafc80d091d3084b4343f5d3 (diff)
fedora kernel: d9aad82f3319f3cfd1aebc01234254ef0c37ad84v3.3.2-1
Signed-off-by: Anton Arapov <>
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+ How to Get Your Patch Accepted Into the Hwmon Subsystem
+ -------------------------------------------------------
+This text is 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/SubmitChecklist
+ Documentation/SubmittingDrivers
+ Documentation/SubmittingPatches
+ Documentation/CodingStyle
+* If your patch generates checkpatch warnings, please refrain from explanations
+ such as "I don't like that coding style". Keep in mind that each unnecessary
+ warning helps hiding a real problem. If you don't like the kernel coding
+ style, don't write kernel drivers.
+* 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 or CONFIG_HOTPLUG, 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. For new drivers, it
+ is most likely prudent to add a dependency on EXPERIMENTAL.
+* Avoid forward declarations if you can. Rearrange the code if necessary.
+* 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.
+* 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.
+* 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 first, then create sysfs entries and register
+ with the hwmon subsystem.
+* 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.