linux-kernel - Re: [PATCH v4 02/11] mfd: Add support for Kontron sl28cpld management controller

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Date:   Fri, 05 Jun 2020 12:09:15 +0200
From:   Michael Walle <michael@...le.cc>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-hwmon@...r.kernel.org, linux-pwm@...r.kernel.org,
        linux-watchdog@...r.kernel.org,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Rob Herring <robh+dt@...nel.org>,
        Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Lee Jones <lee.jones@...aro.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Shawn Guo <shawnguo@...nel.org>, Li Yang <leoyang.li@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <maz@...nel.org>, Mark Brown <broonie@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH v4 02/11] mfd: Add support for Kontron sl28cpld management
 controller

Hi Andy,

Am 2020-06-05 10:01, schrieb Andy Shevchenko:
> On Fri, Jun 5, 2020 at 12:16 AM Michael Walle <michael@...le.cc> wrote:
>> 
>> Add the core support for the board management controller found on the
>> SMARC-sAL28 board. It consists of the following functions:
>>  - watchdog
>>  - GPIO controller
>>  - PWM controller
>>  - fan sensor
>>  - interrupt controller
>> 
>> At the moment, this controller is used on the Kontron SMARC-sAL28 
>> board.
>> 
>> Please note that the MFD driver is defined as bool in the Kconfig
>> because the next patch will add interrupt support.
> 
> ...
> 
>> +config MFD_SL28CPLD
>> +       bool "Kontron sl28 core driver"
>> +       depends on I2C=y
> 
> Why not module?

There are users of the interupt lines provided by the interrupt 
controller.
For example, the gpio-button driver. If this is compiled into the kernel
(which it is by default in the arm64 defconfig), probing will fail 
because
the interrupt is not found. Is there a better way for that? I guess the 
same
is true for the GPIO driver.

> 
>> +       depends on OF
> 
> I didn't find an evidence this is needed.

see below.

> 
> No Compile Test?

ok

>> +       select REGMAP_I2C
>> +       select MFD_CORE
> 
> ...
> 
>> +#include <linux/of_platform.h>
> 
> No evidence of user of this.
> I think you meant mod_devicetable.h.

devm_of_platform_populate(), so I need CONFIG_OF, too right?


>> +static struct i2c_driver sl28cpld_driver = {
>> +       .probe_new = sl28cpld_probe,
>> +       .driver = {
>> +               .name = "sl28cpld",
>> +               .of_match_table = of_match_ptr(sl28cpld_of_match),
> 
> Drop of_match_ptr(). It has a little sense in this context (depends 
> OF).
> It will have a little sense even if you drop depends OF b/c you will
> introduce a compiler warning.

ok

> 
>> +       },
>> +};

-- 
-michael