linux-kernel - Re: [PATCH] rtc: snvs: Use __maybe_unused instead of #if CONFIG_PM

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Message-ID: <1556557953.31309.4.camel@impinj.com>
Date:   Mon, 29 Apr 2019 17:12:34 +0000
From:   Trent Piepho <tpiepho@...inj.com>
To:     "linux-rtc@...r.kernel.org" <linux-rtc@...r.kernel.org>,
        "anson.huang@....com" <anson.huang@....com>,
        "a.zummo@...ertech.it" <a.zummo@...ertech.it>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "alexandre.belloni@...tlin.com" <alexandre.belloni@...tlin.com>
CC:     "linux-imx@....com" <linux-imx@....com>
Subject: Re: [PATCH] rtc: snvs: Use __maybe_unused instead of #if
 CONFIG_PM_SLEEP

On Mon, 2019-04-29 at 07:02 +0000, Anson Huang wrote:
> Use __maybe_unused for power management related functions
> instead of #if CONFIG_PM_SLEEP to simply the code.
> 
> Signed-off-by: Anson Huang <Anson.Huang@....com>

This will result in the functions always being included, even if
PM_SLEEP is off...

>  
> @@ -387,14 +385,6 @@ static const struct dev_pm_ops snvs_rtc_pm_ops = {
>  	.resume_noirq = snvs_rtc_resume_noirq,
>  };

...because they will always be used by the definition of
snvs_rtc_pm_ops here.

In order for this to work, SIMPLE_DEV_PM_OPS() needs to be used,
so that the dev_pm_ops struct is empty when PM is off and the functions
don't get referenced. See: https://lkml.org/lkml/2019/1/17/376