Re: [PATCH] macintosh/via-pmu: Fix build failure when CONFIG_INPUT is disabled

[Finn Thain <fthain@linux-m68k.org>]

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On Mon, 21 Mar 2022, Christophe Leroy wrote:

> 
> 
> Le 21/03/2022 à 05:30, Finn Thain a écrit :
> > drivers/macintosh/via-pmu-event.o: In function `via_pmu_event':
> > via-pmu-event.c:(.text+0x44): undefined reference to `input_event'
> > via-pmu-event.c:(.text+0x68): undefined reference to `input_event'
> > via-pmu-event.c:(.text+0x94): undefined reference to `input_event'
> > via-pmu-event.c:(.text+0xb8): undefined reference to `input_event'
> > drivers/macintosh/via-pmu-event.o: In function `via_pmu_event_init':
> > via-pmu-event.c:(.init.text+0x20): undefined reference to `input_allocate_device'
> > via-pmu-event.c:(.init.text+0xc4): undefined reference to `input_register_device'
> > via-pmu-event.c:(.init.text+0xd4): undefined reference to `input_free_device'
> > make[1]: *** [Makefile:1155: vmlinux] Error 1
> > make: *** [Makefile:350: __build_one_by_one] Error 2
> > 
> > Don't call into the input subsystem unless CONFIG_INPUT is built-in.
> > 
> > Reported-by: kernel test robot <lkp@intel.com>
> > Cc: Michael Ellerman <mpe@ellerman.id.au>
> > Cc: Geert Uytterhoeven <geert@linux-m68k.org>
> > Cc: Randy Dunlap <rdunlap@infradead.org>
> > Signed-off-by: Finn Thain <fthain@linux-m68k.org>
> > ---
> > This is equivalent to the patch I sent a couple of days ago. This one
> > is slightly longer and adds a new symbol so that Kconfig logic can been
> > used instead of Makefile logic in case reviewers prefer that.
> > ---
> >   drivers/macintosh/Kconfig   | 5 +++++
> >   drivers/macintosh/Makefile  | 3 ++-
> >   drivers/macintosh/via-pmu.c | 2 ++
> >   3 files changed, 9 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/macintosh/Kconfig b/drivers/macintosh/Kconfig
> > index 5cdc361da37c..b9102f051bbb 100644
> > --- a/drivers/macintosh/Kconfig
> > +++ b/drivers/macintosh/Kconfig
> > @@ -67,6 +67,11 @@ config ADB_PMU
> >   	  this device; you should do so if your machine is one of those
> >   	  mentioned above.
> >   
> > +config ADB_PMU_EVENT
> > +	bool
> > +	depends on ADB_PMU && INPUT=y
> > +	default y
> 
> Could be reduced to
> 
> config ADB_PMU_EVENT
> 	def_bool y if ADB_PMU && INPUT=y
> 

That's great but my question remains unanswered: why the aversion to 
conditionals in Makefiles, when that would be simpler (no new symbol)?