linux-kernel - Re: [PATCH v3 2/3] hwmon: da9063: HWMON driver

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Message-ID: <3a2f0b72-f790-435b-ebae-6b1afd19f707@roeck-us.net>
Date:   Sat, 10 Jul 2021 22:45:44 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Vincent Pelletier <plr.vincent@...il.com>
Cc:     Jean Delvare <jdelvare@...e.com>, Jonathan Corbet <corbet@....net>,
        Support Opensource <support.opensource@...semi.com>,
        Lee Jones <lee.jones@...aro.org>, linux-hwmon@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Opensource [Steve Twiss]" <stwiss.opensource@...semi.com>
Subject: Re: [PATCH v3 2/3] hwmon: da9063: HWMON driver

On 7/10/21 9:44 PM, Vincent Pelletier wrote:
> On Sun, 11 Jul 2021 02:55:02 +0000, Vincent Pelletier <plr.vincent@...il.com> wrote:
>> On Sat, 10 Jul 2021 09:08:13 -0700, Guenter Roeck <linux@...ck-us.net> wrote:
>>> Unnecessary include.
>> [...]
>>> I don't immediately see where this include is needed. Is this a
>>> leftover ?
>> [...]
>>> Same here.
>>
>> Are there ways to systematically tell which includes are useless
>> besides commenting them out all and uncommenting until it compiles ?
>> (if that is even a good idea)
> 
> I tried this, just to get a baseline: the module compiles with just
>    linux/hwmon.h
>    linux/mfd/da9063/core.h
>    linux/module.h
>    linux/platform_device.h
>    linux/regmap.h
> 
> Beyond what you suggested this also gets rid of:
> - seems reasonable:
>    - linux/delay.h
>    - linux/init.h
>    - linux/slab.h

... except that slab.h was probably originally included for kzalloc().
The driver now uses devm_kzalloc() which is defined in linux/device.h,
so you'll need to include that instead.

> - looks suspicious to me:
>    - linux/err.h, which means the error constants are indirectly
>      imported. Removing it feels brittle.

It also defines PTR_ERR_OR_ZERO(), so it is definitely needed.

Guenter

>    - linux/kernel.h, although to my surprise a lot of c files do not
>      include it.
> 
> By default I'll drop the former and keep the latter in the
> next version, please let me know if another combination is preferred.
>