Re: [PATCH 2/3] PM: define new ASSIGN_*_PM_OPS macros based on assign_if

[Greg Kroah-Hartman]

On Sat, Mar 01, 2014 at 12:06:33PM +0100, Pavel Machek wrote:
> Hi!
> 
> > > +#define ASSIGN_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
> > > +	.suspend = assign_if_pm_sleep(suspend_fn), \
> > > +	.resume = assign_if_pm_sleep(resume_fn), \
> > > +	.freeze = assign_if_pm_sleep(suspend_fn), \
> > > +	.thaw = assign_if_pm_sleep(resume_fn), \
> > > +	.poweroff = assign_if_pm_sleep(suspend_fn), \
> > > +	.restore = assign_if_pm_sleep(resume_fn),
> > 
> > Ugh, what a mess, really?  Is it that hard to get the #ifdef right in
> > the code?  Why not just always define the functions and then also always
> > have them in the structures, and if the feature isn't enabled, just
> > don't call/use them?
> 
> The functions may not compile with CONFIG_PM disabled. (And #ifdefs in
> the code are considered ugly).
> 
> > Yes, it would cause a _very_ tiny increase in code size if the option is
> > disabled, but really, does anyone ever disable those options becides on
> > the dreaded 'make randconfig' checkers?
> 
> We don't want CONFIG_PM complexity on some embedded systems...

Really, what embedded systems do not want this?

> and it is useful tostart with simple (!PM) system when introducing new
> board.

I'm not saying to disable the option, I'm saying to stop worrying about
saving a few hundred bytes in individual drivers with this crazy #ifdef
and macro mess that no one understands and always gets wrong.

greg k-h
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