hwmon: Add submitting-patches checklist to documentation

	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

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* 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.