On Thu, Apr 8, 2021 at 11:00 PM Masahiro Yamada <masahi...@kernel.org> wrote:
>
> Drivers typically surround suspend and resume callbacks with #ifdef
> CONFIG_PM(_SLEEP) or mark them as __maybe_unused in order to avoid
> -Wunused-const-variable warnings.
>
> With this commit, drivers will be able to remove #ifdef CONFIG_PM(_SLEEP)
> and __maybe_unsed because unused functions are dropped by the compiler
> instead of the preprocessor.
>
> Signed-off-by: Masahiro Yamada <masahi...@kernel.org>
I tried this before and could not get it to work right.
>
> -#ifdef CONFIG_PM_SLEEP
> +#define pm_ptr(_ptr) PTR_IF(IS_ENABLED(CONFIG_PM), _ptr)
> +#define pm_sleep_ptr(_ptr) PTR_IF(IS_ENABLED(CONFIG_PM_SLEEP), _ptr)
> +
> #define SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
> - .suspend = suspend_fn, \
> - .resume = resume_fn, \
> - .freeze = suspend_fn, \
> - .thaw = resume_fn, \
> - .poweroff = suspend_fn, \
> - .restore = resume_fn,
> -#else
> -#define SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn)
> -#endif
> + .suspend = pm_sleep_ptr(suspend_fn), \
> + .resume = pm_sleep_ptr(resume_fn), \
> + .freeze = pm_sleep_ptr(suspend_fn), \
> + .thaw = pm_sleep_ptr(resume_fn), \
> + .poweroff = pm_sleep_ptr(suspend_fn), \
> + .restore = pm_sleep_ptr(resume_fn),
The problem that I think you inevitably hit is that you run into a missing
declaration for any driver that still uses an #ifdef around a static
function.
The only way I can see us doing this is to create a new set of
macros that behave like the version you propose here but leave
the old macros in place until the last such #ifdef has been removed.
Arnd
