8c27ceff36
The previous patch renamed several files that are cross-referenced along the Kernel documentation. Adjust the links to point to the right places. Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
145 lines
6.5 KiB
Text
145 lines
6.5 KiB
Text
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.
|