linux-kernel - Re: [PATCH v2 6/6] usb: dwc3: exynos: Switch from CONFIG_PM_SLEEP guards to pm_sleep

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Message-ID: <CANAwSgS-oD86obNUHcjAwfD+3v6VyWidTezwtihJBOC8VWHPjg@mail.gmail.com>
Date: Thu, 11 Apr 2024 13:20:31 +0530
From: Anand Moon <linux.amoon@...il.com>
To: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>, Alim Akhtar <alim.akhtar@...sung.com>, 
	Christophe JAILLET <christophe.jaillet@...adoo.fr>, Johan Hovold <johan@...nel.org>, 
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>, 
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, 
	"linux-samsung-soc@...r.kernel.org" <linux-samsung-soc@...r.kernel.org>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 6/6] usb: dwc3: exynos: Switch from CONFIG_PM_SLEEP
 guards to pm_sleep_ptr()

Hi Thinh,

On Thu, 11 Apr 2024 at 04:56, Thinh Nguyen <Thinh.Nguyen@...opsys.com> wrote:
>
> On Wed, Apr 10, 2024, Anand Moon wrote:
> > Hi Thinh,
> >
> > On Tue, 9 Apr 2024 at 07:24, Thinh Nguyen <Thinh.Nguyen@...opsys.com> wrote:
> > >
> > > On Thu, Apr 04, 2024, Anand Moon wrote:
> > > > Use the new PM macros for the suspend and resume functions to be
> > > > automatically dropped by the compiler when CONFIG_PM_SLEEP are disabled,
> > > > without having to use #ifdef guards. If CONFIG_PM_SLEEP unused,
> > > > they will simply be discarded by the compiler.
> > > >
> > > > Signed-off-by: Anand Moon <linux.amoon@...il.com>
> > > > ---
> > > > v2: add __maybe_unused to suspend/resume functions in case CONFIG_PM is
> > > >    disabled.
> > >
> > > The compiler discards the code, yet we still need __maybe_unused?
> > >
> > Earlier version had not added this since but I removed the
> > guard.CONFIG_PM_SLEEP.
> > added __maybe_unused just to safeguard the function.
> >
> > I have tried to build with config by disabling CONFIG_PM and CONFIG_PM_SLEEP
> > but could get the warning compilation by adding flag W=1
> > -Werror=unused-function.
> >
>
> <snip>
>
> >
> > But since these CONFIG_PM and CONFIG_PM_SLEEP cannot be disabled,
> > I am not getting any warning related to these functions.
> >
> > Do you want me to remove __maybe_unused ?
> >
>
> The warning was there as expected. You should to use it along with
> DEFINE_SIMPLE_DEV_PM_OPS(). Let me know if you still see the same
> warning.
>

But the warnings are related to the following macros

#define PTR_IF(cond, ptr) ((cond) ? (ptr) : NULL)

#define pm_ptr(_ptr) PTR_IF(IS_ENABLED(CONFIG_PM), (_ptr))
#define pm_sleep_ptr(_ptr) PTR_IF(IS_ENABLED(CONFIG_PM_SLEEP), (_ptr))

So if we can disable CONFIG_PM and CONFIG_PM_SLEEP options
the relevant function with the above macro will be set to NULL.
in this case, the compiler will discard the function in SET_SYSTEM_SLEEP_PM_OPS

> BR,
> Thinh

Thanks
-Anand