Re: [PATCH] rtc: stm32: Use NOIRQ_SYSTEM_SLEEP_PM_OPS()

["Arnd Bergmann" <arnd@arndb.de>]

On Wed, Aug 16, 2023, at 00:16, Nathan Chancellor wrote:
> After the switch to SET_NOIRQ_SYSTEM_SLEEP_PM_OPS() and a subsequent
> fix, stm32_rtc_{suspend,resume}() are unused when CONFIG_PM_SLEEP is not
> set because SET_NOIRQ_SYSTEM_SLEEP_PM_OPS() is a no-op in that
> configuration:
>
>   drivers/rtc/rtc-stm32.c:904:12: error: 'stm32_rtc_resume' defined but 
> not used [-Werror=unused-function]
>     904 | static int stm32_rtc_resume(struct device *dev)
>         |            ^~~~~~~~~~~~~~~~
>   drivers/rtc/rtc-stm32.c:894:12: error: 'stm32_rtc_suspend' defined 
> but not used [-Werror=unused-function]
>     894 | static int stm32_rtc_suspend(struct device *dev)
>         |            ^~~~~~~~~~~~~~~~~
>   cc1: all warnings being treated as errors
>
> The non-"SET_" version of this macro, NOIRQ_SYSTEM_SLEEP_PM_OPS(), is
> designed to handle this situation by only assigning the callbacks when
> CONFIG_PM_SLEEP is set while allowing the functions to appear used to
> the compiler. Switch to that macro to resolve the warnings. There is no
> functional change with this, as SET_NOIRQ_SYSTEM_SLEEP_PM_OPS() is
> defined using NOIRQ_SYSTEM_SLEEP_PM_OPS() when CONFIG_PM_SLEEP is set.
>
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Reviewed-by: Arnd Bergmann <arnd@arndb.de>

> ---
> I am not sure what to do about a Fixes: tag for this change. I am not
> sure how Arnd triggered the error/warning in commit a69c610e13e2 ("rtc:
> stm32: remove incorrect #ifdef check"), since from what I can tell,
> SET_NOIRQ_SYSTEM_SLEEP_PM_OPS() is only defined in terms of
> NOIRQ_SYSTEM_SLEEP_PM_OPS() when CONFIG_PM_SLEEP is set, so I am not
> sure how those functions could be absent in the source file but used in
> NOIRQ_SYSTEM_SLEEP_PM_OPS() when CONFIG_PM_SLEEP is unset... I could be
> missing something though.

It was a mistake on my end: my randconfig tree has an experimental
patch to clean up all 13 users of SET_NOIRQ_SYSTEM_SLEEP_PM_OPS()
that actually rely on the old behavior and changing the definition
to be the same as NOIRQ_SYSTEM_SLEEP_PM_OPS. I should get back
to that series and actually send out patches towards removing
the deprecated helpers.

      Arnd