linux-kernel - Re: [PATCH v1 2/4] usb: ehci-exynos: Switch from CONFIG_PM guards to pm

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Message-ID: <CANAwSgT5cvfwQmv6SbMoKoNA1vHYEpbhvc+6rfaMr-36bHnLUQ@mail.gmail.com>
Date: Sat, 2 Mar 2024 21:11:49 +0530
From: Anand Moon <linux.amoon@...il.com>
To: Alan Stern <stern@...land.harvard.edu>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>, Alim Akhtar <alim.akhtar@...sung.com>, 
	linux-usb@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 2/4] usb: ehci-exynos: Switch from CONFIG_PM guards to pm_ptr()

Hi Alan,

On Sat, 2 Mar 2024 at 01:58, Alan Stern <stern@...land.harvard.edu> wrote:
>
> On Sat, Mar 02, 2024 at 01:08:09AM +0530, Anand Moon wrote:
> > Use the new PM macros for the suspend and resume functions to be
> > automatically dropped by the compiler when CONFIG_PM are disabled,
> > without having to use #ifdef guards. If CONFIG_PM unused,
> > they will simply be discarded by the compiler.
> >
> > Use RUNTIME_PM_OPS runtime macro for suspend/resume function.
> >
> > Signed-off-by: Anand Moon <linux.amoon@...il.com>
> > ---
> >  drivers/usb/host/ehci-exynos.c | 10 ++--------
> >  1 file changed, 2 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/usb/host/ehci-exynos.c b/drivers/usb/host/ehci-exynos.c
> > index 05aa3d9c2a3b..4676f45655cd 100644
> > --- a/drivers/usb/host/ehci-exynos.c
> > +++ b/drivers/usb/host/ehci-exynos.c
> > @@ -234,7 +234,6 @@ static void exynos_ehci_remove(struct platform_device *pdev)
> >       usb_put_hcd(hcd);
> >  }
> >
> > -#ifdef CONFIG_PM
> >  static int exynos_ehci_suspend(struct device *dev)
> >  {
> >       struct usb_hcd *hcd = dev_get_drvdata(dev);
> > @@ -268,14 +267,9 @@ static int exynos_ehci_resume(struct device *dev)
> >       ehci_resume(hcd, false);
> >       return 0;
> >  }
> > -#else
> > -#define exynos_ehci_suspend  NULL
> > -#define exynos_ehci_resume   NULL
> > -#endif
>
> Doesn't this now generate warnings about functions being defined but not
> used when you build with CONFIG_PM disabled?
>
Yes I have tried compile the kernel with disable CONFIG_PM=n and
CONFIG_PM_SLEEP=n
But it's getting selected  by default.

Also compiled with W=1 and found no warning with these patches.
To be safe I will add __maybe_unused to suspend / resume functions in
the next version.

diff --git a/arch/arm/configs/exynos_defconfig
b/arch/arm/configs/exynos_defconfig
index c98d5ff8a1ed..e96f5c3bf8c1 100644
--- a/arch/arm/configs/exynos_defconfig
+++ b/arch/arm/configs/exynos_defconfig
@@ -29,8 +29,10 @@ 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 is not set
+# CONFIG_PM is not set
+# CONFIG_PM_DEBUG is not set
+# CONFIG_PM_ADVANCED_DEBUG is not set
 CONFIG_ENERGY_MODEL=y
 CONFIG_KALLSYMS_ALL=y
 CONFIG_MODULES=y

> Alan Stern

Thanks

-Anand