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

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Date:   Thu, 8 Aug 2019 19:53:13 +0000
From:   "Vaittinen, Matti" <Matti.Vaittinen@...rohmeurope.com>
To:     "yuehaibing@...wei.com" <yuehaibing@...wei.com>,
        "arnd@...db.de" <arnd@...db.de>
CC:     "linux-rtc@...r.kernel.org" <linux-rtc@...r.kernel.org>,
        "a.zummo@...ertech.it" <a.zummo@...ertech.it>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "alexandre.belloni@...tlin.com" <alexandre.belloni@...tlin.com>,
        "lee.jones@...aro.org" <lee.jones@...aro.org>,
        "rdunlap@...radead.org" <rdunlap@...radead.org>
Subject: Re: [PATCH] rtc: bd70528: fix link error

Hello All,

On Thu, 2019-08-08 at 10:29 +0800, Yuehaibing wrote:
> On 2019/7/9 13:25, Vaittinen, Matti wrote:
> > Hello Arnd,
> > 
> > (Added Randy who also sent a patch to fix this)
> > 
> > On Mon, 2019-07-08 at 18:10 +0200, Arnd Bergmann wrote:
> > > 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
> > > .
> > 
> > Thanks for teaching me Arnd! That is clever :) We need something
> > like
> > 
> > depends on MFD_ROHM_BD70528 && (BD70528_WATCHDOG ||
> > !BD70528_WATCHDOG)
> > 
> > (I'm not sure if parenthesis are Ok and respected in Kconfig). I
> > would
> > never have thought of BD70528_WATCHDOG || !BD70528_WATCHDOG - it
> > looks
> > awkward at first sight but indeed - depends on BD70528_WATCHDOG
> > disallows BD70528_WATCHDOG=m with RTC_DRV_BD70528=y while
> > !BD70528_WATCHDOG allows BD70528_WATCHDOG=n. Brilliant and exactly
> > what
> > we need :) Thanks a bunch!
> 
> Hello Vaittinen,
> 
> the issue still exists in linux-next 20190807, any plan?
> 

> Sorry folks. I thought Arnd would send new patch - I didn't want to
> steal his work ;) I will be back to my normal life next week so I
> will send a patch at monday if the issue is still open!

Br,
	Matti