linux-kernel - RE: [PATCH] tpm/tpm_crb: mark PM functions as __maybe

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Date:   Mon, 20 Mar 2017 12:11:55 +0000
From:   "Winkler, Tomas" <tomas.winkler@...el.com>
To:     Arnd Bergmann <arnd@...db.de>, Peter Huewe <peterhuewe@....de>,
        "Marcel Selhorst" <tpmdd@...horst.net>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
CC:     Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        Jerry Snitselaar <jsnitsel@...hat.com>,
        "tpmdd-devel@...ts.sourceforge.net" 
        <tpmdd-devel@...ts.sourceforge.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] tpm/tpm_crb: mark PM functions as __maybe_unused

> 
> When CONFIG_PM_SLEEP is disabled, we get a warning about unused
> functions:
> 
> drivers/char/tpm/tpm_crb.c:551:12: error: 'crb_pm_resume' defined but not
> used [-Werror=unused-function]
> drivers/char/tpm/tpm_crb.c:540:12: error: 'crb_pm_suspend' defined but not
> used [-Werror=unused-function]
>
Note that the runtime_pm functions are not affected by this issue the macro SET_RUNTIME_PM_OPS
is under CONFIG_PM. This patch does more than described. 

> We could solve this with more sophistated #ifdefs, but a simpler and safer way
> is to just mark them as __maybe_unused.

> 
> Fixes: 848efcfb560c ("tpm/tpm_crb: enter the low power state upon device
> suspend")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  drivers/char/tpm/tpm_crb.c | 11 ++++-------
>  1 file changed, 4 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c index
> 1dfc37e33c02..15f1118982a6 100644
> --- a/drivers/char/tpm/tpm_crb.c
> +++ b/drivers/char/tpm/tpm_crb.c
> @@ -519,8 +519,7 @@ static int crb_acpi_remove(struct acpi_device *device)
>  	return 0;
>  }
> 
> -#ifdef CONFIG_PM
> -static int crb_pm_runtime_suspend(struct device *dev)
> +static __maybe_unused int crb_pm_runtime_suspend(struct device *dev)
>  {
>  	struct tpm_chip *chip = dev_get_drvdata(dev);
>  	struct crb_priv *priv = dev_get_drvdata(&chip->dev); @@ -528,7
> +527,7 @@ static int crb_pm_runtime_suspend(struct device *dev)
>  	return crb_go_idle(dev, priv);
>  }
> 
> -static int crb_pm_runtime_resume(struct device *dev)
> +static __maybe_unused int crb_pm_runtime_resume(struct device *dev)
>  {
>  	struct tpm_chip *chip = dev_get_drvdata(dev);
>  	struct crb_priv *priv = dev_get_drvdata(&chip->dev); @@ -536,7
> +535,7 @@ static int crb_pm_runtime_resume(struct device *dev)
>  	return crb_cmd_ready(dev, priv);
>  }
> 
> -static int crb_pm_suspend(struct device *dev)
> +static __maybe_unused int crb_pm_suspend(struct device *dev)
>  {
>  	int ret;
> 
> @@ -547,7 +546,7 @@ static int crb_pm_suspend(struct device *dev)
>  	return crb_pm_runtime_suspend(dev);
>  }

It's enough to 
#endif /* CONFIG_PM */
#ifdef CONFIG_PM_SLEEP
> -static int crb_pm_resume(struct device *dev)
> +static __maybe_unused int crb_pm_resume(struct device *dev)
>  {
>  	int ret;
> 
> @@ -558,8 +557,6 @@ static int crb_pm_resume(struct device *dev)
>  	return tpm_pm_resume(dev);
>  }
> 
> -#endif /* CONFIG_PM */
And 
#endif CONFIG_PM_SLEEP

> -
>  static const struct dev_pm_ops crb_pm = {
>  	SET_SYSTEM_SLEEP_PM_OPS(crb_pm_suspend, crb_pm_resume)
>  	SET_RUNTIME_PM_OPS(crb_pm_runtime_suspend,
> crb_pm_runtime_resume, NULL)
> --
> 2.9.0