linux-kernel - Re: [PATCH] iio: accel: fxls8962af: fix i2c dependency

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Date:   Wed, 21 Jul 2021 20:33:05 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Arnd Bergmann <arnd@...nel.org>
Cc:     Jonathan Cameron <jic23@...nel.org>,
        Sean Nyekjaer <sean@...nix.com>, Arnd Bergmann <arnd@...db.de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Linus Walleij <linus.walleij@...aro.org>,
        Stephan Gerhold <stephan@...hold.net>,
        Hans de Goede <hdegoede@...hat.com>,
        Tomas Melin <tomas.melin@...sala.com>,
        Mike Looijmans <mike.looijmans@...ic.nl>,
        Alexandru Ardelean <aardelean@...iqon.com>,
        linux-iio@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] iio: accel: fxls8962af: fix i2c dependency

On Wed, Jul 21, 2021 at 7:12 PM Arnd Bergmann <arnd@...nel.org> wrote:
> On Wed, Jul 21, 2021 at 5:52 PM Andy Shevchenko
> <andy.shevchenko@...il.com> wrote:
> > On Wed, Jul 21, 2021 at 6:13 PM Arnd Bergmann <arnd@...nel.org> wrote:

...

> > >  config FXLS8962AF
> > >         tristate
> > > +       depends on I2C || !I2C # cannot be built-in for modular I2C
> >
> > Can you enlighten me how this will not be a no-op?
>
> This part does nothing, it only causes a warning when FXLS8962AF
> gets selected =y when I2C=m.

This is something new to me. But shouldn't the other chunk guarantee
that warning won't happen?

> The important bit is the other hunk that adds the same dependency
> to the FXLS8962AF_SPI symbol, which enforces that either I2C
> is completely disabled, or treated as a dependency that prevents
> the user from setting FXLS8962AF_SPI=y when that would cause
> a link failure.

This part I understand and neither object to nor comment on.

> The effect is similar to a 'depends on SND_SOC_I2C_AND_SPI',
> except we only need it on the SPI symbol here because the SPI
> core cannot be in a module itself.

I see. Thanks for elaboration.

-- 
With Best Regards,
Andy Shevchenko