linux-kernel - Re: [PATCH -next] rtc: pcf2127: Fix build error without CONFIG_WATCHDOG

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Message-ID: <20190826184622.GA7766@roeck-us.net>
Date:   Mon, 26 Aug 2019 11:46:22 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Bruno Thomsen <bruno.thomsen@...il.com>
Cc:     Yuehaibing <yuehaibing@...wei.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        a.zummo@...ertech.it, linux-rtc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH -next] rtc: pcf2127: Fix build error without
 CONFIG_WATCHDOG_CORE

On Mon, Aug 26, 2019 at 08:13:35PM +0200, Bruno Thomsen wrote:
> Den man. 26. aug. 2019 kl. 15.20 skrev Guenter Roeck <linux@...ck-us.net>:
> >
> > On 8/26/19 1:12 AM, Yuehaibing wrote:
> > >
> > >
> > > On 2019/8/23 22:05, Alexandre Belloni wrote:
> > >> On 23/08/2019 20:45:53+0800, YueHaibing wrote:
> > >>> If WATCHDOG_CORE is not set, build fails:
> > >>>
> > >>> drivers/rtc/rtc-pcf2127.o: In function `pcf2127_probe.isra.6':
> > >>> drivers/rtc/rtc-pcf2127.c:478: undefined reference to `devm_watchdog_register_device'
> > >>>
> > >>> Add WATCHDOG_CORE Kconfig dependency to fix this.
> > >>>
> > >>> Reported-by: Hulk Robot <hulkci@...wei.com>
> > >>> Fixes: bbc597561ce1 ("rtc: pcf2127: add watchdog feature support")
> > >>> Signed-off-by: YueHaibing <yuehaibing@...wei.com>
> > >>> ---
> > >>>   drivers/rtc/Kconfig | 2 ++
> > >>>   1 file changed, 2 insertions(+)
> > >>>
> > >>> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> > >>> index 25af63d..9dce7dc 100644
> > >>> --- a/drivers/rtc/Kconfig
> > >>> +++ b/drivers/rtc/Kconfig
> > >>> @@ -886,6 +886,8 @@ config RTC_DRV_DS3232_HWMON
> > >>>   config RTC_DRV_PCF2127
> > >>>     tristate "NXP PCF2127"
> > >>>     depends on RTC_I2C_AND_SPI
> > >>> +   depends on WATCHDOG
> > >>
> > >> Definitively not, I fixed it that way:
> > >> +       select WATCHDOG_CORE if WATCHDOG
> > >
> > >
> > > No, this still fails while WATCHDOG is not set
> > >
> >
> > Correct, there are no dummy functions for watchdog device registration.
> > There would have to be conditional code in the driver if the watchdog
> > is supposed to be optional.
> 
> Hi
> 
> During review of version 1, there was a wish for the watchdog feature not
> to be hidden behind Kconfig option, e.g. RTC_DRV_PCF2127_WDT, as
> it would not result in a much bigger driver.
> 
> I did not add any other selects/depends on in Kconfig as
> RTC_DRV_DS1374_WDT and RTC_DRV_M41T80_WDT options
> does not select WATCHDOG_CORE and/or WATCHDOG either.

Those drivers do not use the watchdog core but re-implement its
functionality. RTC_DRV_M41T80_WDT was written before the watchdog
core existed, so this is understandable. You would have to ask the
author of RTC_DRV_DS1374_WDT support why it doesn't use the
watchdog core but re-implements it.

> DS1374 and M41T80 does not seem to check on any other
> WATCHDOG defines other then their _WDT Kconfig.
> 
> I can create a patch that hides the watchdog code if WATCHDOG
> define is not set, if that's the right way?
> 

That is for you and the rtc maintainer to decide.

Guenter