Messages in this thread | | | Date | Mon, 20 Jun 2022 12:39:57 +0300 | From | Andy Shevchenko <> | Subject | Re: [PATCH v1 2/2] mfd: intel_soc_pmic_chtwc: Switch from __maybe_unused to pm_sleep_ptr() etc |
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On Mon, Jun 20, 2022 at 10:38:34AM +0200, Hans de Goede wrote: > On 6/16/22 19:10, Andy Shevchenko wrote: > > Letting the compiler remove these functions when the kernel is built > > without CONFIG_PM_SLEEP support is simpler and less heavier for builds > > than the use of __maybe_unused attributes. > > > > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > > I don't see how this helps, __maybe_unused only means the compiler should not > warn AFAIK it is still allowed to remove static globals which are unused > even of they are marked __maybe_unused ?
__maybe_unused will force compiler to compile and linker to drop the section. The proposed approach saves resources on build, i.e. it's already compiler that decides not to compile the code.
> And DEFINE_SIMPLE_DEV_PM_OPS does not mark the dev_pm_ops as > __maybe_unused where as pm_sleep_ptr() will not reference the struct > when CONFIG_PM is not set. > > But I guess that the new PTR_IF magic: > > #define PTR_IF(cond, ptr) ((cond) ? (ptr) : NULL) > > Still counts as referencing the struct so we don't get > an unused warning and since cond is a const 0 value the compiler > can optimize things away ?
See above, it's not olny about warning and compiler.
-- With Best Regards, Andy Shevchenko
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