Hi,

Arnd Bergmann <arnd@arndb.de> writes:
> Starting with v4.8-rc5, we get a warning about the dwc3_pci_pm_dummy function
> when CONFIG_PM_SLEEP is disabled:
>
> drivers/usb/dwc3/dwc3-pci.c:253:12: warning: 'dwc3_pci_pm_dummy' defined but not used
>
> Using __maybe_unused instead of #ifdef lets the compiler figure out
> whether it should drop the definitions silently and avoids this warning.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Fixes: f6c274e11e3b ("usb: dwc3: pci: runtime_resume child device")
> ---
>  drivers/usb/dwc3/dwc3-pci.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
>
> After we fixed all other warnings reported by kernelci.org, this is
> now the only thing we get a warning for in the configurations we build,
> so it would be good to get this fixed before v4.8 to get a clean
> build for the first time in a release.
>
> diff --git a/drivers/usb/dwc3/dwc3-pci.c b/drivers/usb/dwc3/dwc3-pci.c
> index 0a32430f4c41..6a82b36f0d59 100644
> --- a/drivers/usb/dwc3/dwc3-pci.c
> +++ b/drivers/usb/dwc3/dwc3-pci.c
> @@ -234,8 +234,7 @@ static const struct pci_device_id dwc3_pci_id_table[] = {
>  };
>  MODULE_DEVICE_TABLE(pci, dwc3_pci_id_table);
>  
> -#ifdef CONFIG_PM
> -static int dwc3_pci_runtime_suspend(struct device *dev)
> +static int __maybe_unused dwc3_pci_runtime_suspend(struct device *dev)
>  {
>  	if (device_run_wake(dev))
>  		return 0;
> @@ -243,14 +242,14 @@ static int dwc3_pci_runtime_suspend(struct device *dev)
>  	return -EBUSY;
>  }
>  
> -static int dwc3_pci_runtime_resume(struct device *dev)
> +static int __maybe_unused dwc3_pci_runtime_resume(struct device *dev)
>  {
>  	struct platform_device *dwc3 = dev_get_drvdata(dev);
>  
>  	return pm_runtime_get(&dwc3->dev);
>  }
>  
> -static int dwc3_pci_pm_dummy(struct device *dev)
> +static int __maybe_unused dwc3_pci_pm_dummy(struct device *dev)
>  {
>  	/*
>  	 * There's nothing to do here. No, seriously. Everything is either taken
> @@ -262,7 +261,6 @@ static int dwc3_pci_pm_dummy(struct device *dev)
>  	 */
>  	return 0;
>  }
> -#endif /* CONFIG_PM */

seems like it would've been enough to define dwc3_pci_pm_dummy() if
CONFIG_PM_SLEEP. Right? IOW:

diff --git a/drivers/usb/dwc3/dwc3-pci.c b/drivers/usb/dwc3/dwc3-pci.c
index 0a32430f4c41..6df0f5dad9a4 100644
--- a/drivers/usb/dwc3/dwc3-pci.c
+++ b/drivers/usb/dwc3/dwc3-pci.c
@@ -249,7 +249,9 @@ static int dwc3_pci_runtime_resume(struct device *dev)
 
        return pm_runtime_get(&dwc3->dev);
 }
+#endif /* CONFIG_PM */
 
+#ifdef CONFIG_PM_SLEEP
 static int dwc3_pci_pm_dummy(struct device *dev)
 {
        /*
@@ -262,7 +264,7 @@ static int dwc3_pci_pm_dummy(struct device *dev)
         */
        return 0;
 }
-#endif /* CONFIG_PM */
+#endif /* CONFIG_PM_SLEEP */
 
 static struct dev_pm_ops dwc3_pci_dev_pm_ops = {
        SET_SYSTEM_SLEEP_PM_OPS(dwc3_pci_pm_dummy, dwc3_pci_pm_dummy)

Can you check if this is enough for you? Works just fine here.

-- 
balbi