Re: [PATCH] power: supply: add stubs for notifier registration helpers

[Randy Dunlap]

On 8/5/26 11:54 AM, Elson Serrao wrote:
> power_supply_reg_notifier() and power_supply_unreg_notifier() are declared
> unconditionally, with no fallback when CONFIG_POWER_SUPPLY is disabled.
> Any driver that calls them unconditionally fails to link:
> 
> ERROR: modpost: "power_supply_unreg_notifier" [drivers/usb/dwc3/dwc3.ko]
> undefined!
> ERROR: modpost: "power_supply_reg_notifier" [drivers/usb/dwc3/dwc3.ko]
> undefined!
> 
> Fix this by adding stub functions for these calls.
> 
> Fixes: 7c87ef27af79 ("usb: dwc3: avoid probe deferral when USB power supply is not available")
> Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
> Closes: https://lore.kernel.org/all/a9dd53b3-0666-404a-99e0-76617ae3f944@xxxxxxxxxxxxx/
> Signed-off-by: Elson Serrao <elson.serrao@xxxxxxxxxxxxxxxx>

Tested-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Acked-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>

Thanks.

> ---
>  include/linux/power_supply.h | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
> index a9c056f13077..e749d2189335 100644
> --- a/include/linux/power_supply.h
> +++ b/include/linux/power_supply.h
> @@ -816,15 +816,18 @@ struct power_supply_battery_info {
>  	int bti_resistance_tolerance;
>  };
>  
> +#if IS_ENABLED(CONFIG_POWER_SUPPLY)
>  extern int power_supply_reg_notifier(struct notifier_block *nb);
>  extern void power_supply_unreg_notifier(struct notifier_block *nb);
> -#if IS_ENABLED(CONFIG_POWER_SUPPLY)
>  extern struct power_supply *power_supply_get_by_name(const char *name);
>  extern int __must_check power_supply_get_system_batteries(struct device *dev,
>  							  struct power_supply ***psys);
>  extern void power_supply_put_system_batteries(struct power_supply **psys, int count);
>  extern void power_supply_put(struct power_supply *psy);
>  #else
> +static inline int power_supply_reg_notifier(struct notifier_block *nb)
> +{ return -EOPNOTSUPP; }
> +static inline void power_supply_unreg_notifier(struct notifier_block *nb) {}
>  static inline void power_supply_put(struct power_supply *psy) {}
>  static inline struct power_supply *power_supply_get_by_name(const char *name)
>  { return NULL; }

-- 
~Randy