linux-kernel - Re: [PATCH] rtc: bd70528: fix link error

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Message-ID: <CAK8P3a1HNnstePcreH-ZLyiJi3tNcCNJ=VozZUMnp-VLvYLSaA@mail.gmail.com>
Date:   Mon, 8 Jul 2019 18:10:42 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     "Vaittinen, Matti" <Matti.Vaittinen@...rohmeurope.com>
Cc:     "a.zummo@...ertech.it" <a.zummo@...ertech.it>,
        "alexandre.belloni@...tlin.com" <alexandre.belloni@...tlin.com>,
        "linux-rtc@...r.kernel.org" <linux-rtc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "lee.jones@...aro.org" <lee.jones@...aro.org>
Subject: Re: [PATCH] rtc: bd70528: fix link error

On Mon, Jul 8, 2019 at 3:24 PM Vaittinen, Matti
<Matti.Vaittinen@...rohmeurope.com> wrote:

> On Mon, 2019-07-08 at 14:41 +0200, Arnd Bergmann wrote:
> > With CONFIG_BD70528_WATCHDOG=m, a built-in rtc driver cannot call
> > into the low-level functions that are part of the watchdog module:
> >
> > drivers/rtc/rtc-bd70528.o: In function `bd70528_set_time':
> > rtc-bd70528.c:(.text+0x22c): undefined reference to
> > `bd70528_wdt_lock'
> > rtc-bd70528.c:(.text+0x2a8): undefined reference to
> > `bd70528_wdt_unlock'
> > drivers/rtc/rtc-bd70528.o: In function
> > `bd70528_set_rtc_based_timers':
> > rtc-bd70528.c:(.text+0x50c): undefined reference to `bd70528_wdt_set'
> >
> > Add a Kconfig dependency on this driver, but still allow compile-
> > testing
> > without it.
> >
> > Fixes: 32a4a4ebf768 ("rtc: bd70528: Initial support for ROHM bd70528
> > RTC")
> > Signed-off-by: Arnd Bergmann <arnd@...db.de>
> > ---
> >  drivers/rtc/Kconfig | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> > index 3bfc04a86529..7b071cc74422 100644
> > --- a/drivers/rtc/Kconfig
> > +++ b/drivers/rtc/Kconfig
> > @@ -498,8 +498,10 @@ config RTC_DRV_M41T80_WDT
> >       help
> >         If you say Y here you will get support for the
> >         watchdog timer in the ST M41T60 and M41T80 RTC chips series.
> > +
> >  config RTC_DRV_BD70528
> >       tristate "ROHM BD70528 PMIC RTC"
> > +     depends on BD70528_WATCHDOG || (COMPILE_TEST &&
> > !BD70528_WATCHDOG)
>
> I am not fan of this. There may well be use-cases where it is desirable
> to leave the watchdog out but still compile in the RTC. This is why we
> have static inline stubs in the header for cases where WDG is not
> compiled in. (RTC does not need to stop WDG if WDG driver is not
> included)
>
> Adding dependency from RTC to MFD for BD70528 should be done - this
> will avoid most of the issues (And there has been few patches sent for
> this already). But that's still not complete solution because
> configuring RTC and MFD to be built in-kernel and WDG as a module will
> cause errors again.
>
> Is there a way to force WDG in-kernel if RTC is in-kernel? (Or
> disallow configuring RTC in-kernel if WDG is a module - while still
> allow RTC to be built without WDG?

We could make this

        depends on BD70528_WATCHDOG || !BD70528_WATCHDOG

which would allow building with or without watchdog, even when not
compile-testing, but still disallow the combination of
BD70528_WATCHDOG=m with RTC_DRV_BD70528=y.

       Arnd