Re: drivers/clocksource/timer-of.h:35:28: error: field 'clkevt' has incomplete type

[Randy Dunlap <rdunlap@infradead.org>]

On 09/02/17 23:28, kbuild test robot wrote:
> Hi Daniel,
> 
> FYI, the error/warning still remains.
> 
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   d0d6ab53c9abd7dd1070f43a0455328874127ba8
> commit: dc11bae78529526605c5c45c369c9512fd012093 clocksource/drivers: Add timer-of common init routine
> date:   3 months ago
> config: ia64-allyesconfig (attached as .config)
> compiler: ia64-linux-gcc (GCC) 6.2.0
> reproduce:
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         git checkout dc11bae78529526605c5c45c369c9512fd012093
>         # save the attached .config to linux build tree
>         make.cross ARCH=ia64 
> 
> All errors (new ones prefixed by >>):
> 
>    In file included from drivers/clocksource/timer-of.c:25:0:
>>> drivers/clocksource/timer-of.h:35:28: error: field 'clkevt' has incomplete type
>      struct clock_event_device clkevt;
>                                ^~~~~~
>    In file included from include/linux/clk.h:16:0,
>                     from drivers/clocksource/timer-of.c:18:
>    drivers/clocksource/timer-of.h: In function 'to_timer_of':
>    include/linux/kernel.h:854:48: error: initialization from incompatible pointer type [-Werror=incompatible-pointer-types]
>      const typeof( ((type *)0)->member ) *__mptr = (ptr); \
>                                                    ^
>    drivers/clocksource/timer-of.h:44:9: note: in expansion of macro 'container_of'
>      return container_of(clkevt, struct timer_of, clkevt);
>             ^~~~~~~~~~~~
>    drivers/clocksource/timer-of.c: In function 'timer_irq_init':
>    drivers/clocksource/timer-of.c:63:8: error: dereferencing pointer to incomplete type 'struct clock_event_device'
>      clkevt->irq = of_irq->irq;
>            ^~
>    cc1: some warnings being treated as errors
> 
> vim +/clkevt +35 drivers/clocksource/timer-of.h
> 
>     32	
>     33	struct timer_of {
>     34		unsigned int flags;
>   > 35		struct clock_event_device clkevt;
>     36		struct of_timer_base of_base;
>     37		struct of_timer_irq  of_irq;
>     38		struct of_timer_clk  of_clk;
>     39		void *private_data;
>     40	};
>     41	
> 
> ---

Summary:

GENERIC_CLOCKEVENTS is not enabled. (ia64)
COMPILE_TEST=y

#
# Clock Source drivers
#
CONFIG_TIMER_OF=y
CONFIG_CLKSRC_MMIO=y
# CONFIG_CLKSRC_PISTACHIO is not set
CONFIG_ARMV7M_SYSTICK=y
# CONFIG_ATMEL_PIT is not set
CONFIG_CLKSRC_ST_LPC=y

Both ARMV7M_SYSTICK and CLKSRC_ST_LPC select TIMER_OF (if OF, which is enabled)
and select CLKSRC_MMIO.  TIMER_OF depends on GENERIC_CLOCKEVENTS (=n), but
'select' does not care about that "depends on".

This build error only happens because COMPILE_TEST=y.

Any driver that does 'select TIMER_OF' should also depend on GENERIC_CLOCKEVENTS.
The problem is that some drivers do 'select TIMER_OF if OF', so if OF is not
enabled, then we don't need to depend on GENERIC_CLOCKEVENTS.


"O, what a tangled web we weave when first we practise to deceive!" --Walter Scott

Not that we are trying to deceive in this case -- it's just another Kconfig
tangled web.

Arnd: any ideas?


thanks,
-- 
~Randy