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

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Date: Wed, 10 Apr 2024 10:47:10 +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 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.

diff --git a/arch/arm/configs/exynos_defconfig
b/arch/arm/configs/exynos_defconfig
index 7ad48fdda1da..43110e42076e 100644
--- a/arch/arm/configs/exynos_defconfig
+++ b/arch/arm/configs/exynos_defconfig
@@ -29,8 +29,19 @@ CONFIG_ARM_EXYNOS_CPUIDLE=y
 CONFIG_VFP=y
 CONFIG_NEON=y
 CONFIG_KERNEL_MODE_NEON=y
-CONFIG_PM_DEBUG=y
-CONFIG_PM_ADVANCED_DEBUG=y
+CONFIG_PM_SLEEP=n
+CONFIG_PM_SLEEP_SMP=n
+# CONFIG_PM_AUTOSLEEP is not set
+# CONFIG_PM_USERSPACE_AUTOSLEEP is not set
+# CONFIG_PM_WAKELOCKS is not set
+CONFIG_PM=n
+CONFIG_PM_DEBUG=n
+CONFIG_PM_ADVANCED_DEBUG=n
+# CONFIG_PM_TEST_SUSPEND is not set
+# CONFIG_PM_SLEEP_DEBUG=n
+#
+CONFIG_PM_DEBUG=n
+CONFIG_PM_ADVANCED_DEBUG=n
 CONFIG_ENERGY_MODEL=y
 CONFIG_KALLSYMS_ALL=y
 CONFIG_MODULES=y

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 ?

alarm@...hl-xu4b:~/linux-exynos-5.y-devel$ ./buildkernelexynos-arch.sh
arch/arm/configs/exynos_defconfig:43:warning: override: reassigning to
symbol PM_DEBUG
arch/arm/configs/exynos_defconfig:44:warning: override: reassigning to
symbol PM_ADVANCED_DEBUG
#
# configuration written to .config
#
  SYNC    include/config/auto.conf
  CALL    scripts/checksyscalls.sh
  CC      arch/arm/mach-exynos/pm.o

> BR,
> Thinh
>

Thanks
-Anand