Re: [PATCH v2 3/4] iio: adc: at91_adc: add Kconfig dependency on the OF symbol

From: Alexandru Ardelean <ardeleanalex@gmail.com>
To: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Alexandru Ardelean <alexandru.ardelean@analog.com>,
	linux-iio <linux-iio@vger.kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	LKML <linux-kernel@vger.kernel.org>,
	Jonathan Cameron <jic23@kernel.org>,
	Nicolas Ferre <nicolas.ferre@microchip.com>,
	Ludovic Desroches <ludovic.desroches@microchip.com>
Subject: Re: [PATCH v2 3/4] iio: adc: at91_adc: add Kconfig dependency on the OF symbol
Date: Wed, 30 Sep 2020 11:47:44 +0300	[thread overview]
Message-ID: <CA+U=Dsq9Gu6Ayo9k0pzzCD4vA0+4YbfL+HEHSmxDzEZs35g21w@mail.gmail.com> (raw)
In-Reply-To: <20200930073727.GC2804081@piout.net>

On Wed, Sep 30, 2020 at 10:39 AM Alexandre Belloni
<alexandre.belloni@bootlin.com> wrote:
>
> Hi,
>
> On 30/09/2020 09:00:07+0300, Alexandru Ardelean wrote:
> > This tries to solve a warning reported by the lkp bot:
> >
> > >> drivers/iio/adc/at91_adc.c:1439:34: warning: unused variable
> > >> 'at91_adc_dt_ids' [-Wunused-const-variable]
> >    static const struct of_device_id at91_adc_dt_ids[] = {
> >                                     ^
> >    1 warning generated.
> >
> > This shows up with 'compiler: clang version 12.0.0' and W=1 (as the bot
> > mentions).
> >
> > Forward declarations for global variables can be a bit weird; forward
> > function declarations are more common.
> >
> > Maybe another fix for this would have been to prefix with 'extern' the
> > 'at91_adc_dt_ids' variable, thus making it more friendly as a forward
> > declaration. It would look weird, but it would work.
> >
> > But, we can avoid that forward declaration altogether simply by obtaining
> > the private data with of_device_get_match_data().
> >
> > This appeared after commit 4027860dcc4c ("iio: Kconfig: at91_adc: add
> > COMPILE_TEST dependency to driver"), which put this driver on the lkp's bot
> > radar.
> >
>
> Shouldn't all of that be part of the commit message for 1/4? This
> doesn't explicitly explain why you add a dependency on OF.

Hmm, I think I did this patch before drinking my morning coffee.
Looks like it's also a bad commit description.

>
> > Fixes: 4027860dcc4c ("iio: Kconfig: at91_adc: add COMPILE_TEST dependency to driver")
> > Reported-by: kernel test robot <lkp@intel.com>
> > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
> > ---
> >  drivers/iio/adc/Kconfig | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> > index 91ae90514aff..17e9ceb9c6c4 100644
> > --- a/drivers/iio/adc/Kconfig
> > +++ b/drivers/iio/adc/Kconfig
> > @@ -295,7 +295,7 @@ config ASPEED_ADC
> >  config AT91_ADC
> >       tristate "Atmel AT91 ADC"
> >       depends on ARCH_AT91 || COMPILE_TEST
> > -     depends on INPUT && SYSFS
> > +     depends on INPUT && SYSFS && OF
> >       select IIO_BUFFER
> >       select IIO_TRIGGERED_BUFFER
> >       help
> > --
> > 2.17.1
> >
>
> --
> Alexandre Belloni, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com