linux-kernel - Re: [PATCH] power: bq27xxx_battery: avoid unused function warnings

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Message-ID: <56534266.4060708@ti.com>
Date:	Mon, 23 Nov 2015 10:44:22 -0600
From:	"Andrew F. Davis" <afd@...com>
To:	Arnd Bergmann <arnd@...db.de>, <linux-pm@...r.kernel.org>
CC:	Andreas Dannenberg <dannenberg@...com>,
	Pali Rohar <pali.rohar@...il.com>,
	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
	<linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	David Woodhouse <dwmw2@...radead.org>
Subject: Re: [PATCH] power: bq27xxx_battery: avoid unused function warnings

On 11/23/2015 07:42 AM, Arnd Bergmann wrote:
> We can configure the bq27xxx_battery driver with neither the I2C
> nor the platform driver backends, which leaves out all references
> to some of the symbols, causing a couple of warnings in many
> randconfig builds:
>
> drivers/power/bq27xxx_battery.c:288:12: warning: 'bq27xxx_regs' defined but not used [-Wunused-variable]
> drivers/power/bq27xxx_battery.c:994:12: warning: 'bq27xxx_powersupply_init' defined but not used [-Wunused-function]
> drivers/power/bq27xxx_battery.c:1029:13: warning: 'bq27xxx_powersupply_unregister' defined but not used [-Wunused-function]
>
> I first tried replacing the existing #ifdefs with if(IS_ENABLED()
> statements, but that failed because the i2c framework does not
> declare functions when they are left out of the kernel.
>
> This just marks the unused functions as __maybe_unused, which is
> a correct description here. A better fix would be to restructure
> the driver into separate files and only build the common parts
> if at least one of the two bus specific drivers is enabled, but
> that requires much more work and testing on real hardware.
>
> For the time being, my simpler change at least avoids the warnings.
>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>
> diff --git a/drivers/power/bq27xxx_battery.c b/drivers/power/bq27xxx_battery.c
> index 880233ce9343..6c3a447f378b 100644
> --- a/drivers/power/bq27xxx_battery.c
> +++ b/drivers/power/bq27xxx_battery.c
> @@ -285,7 +285,7 @@ static u8 bq27421_regs[] = {
>   	0x18,	/* AP		*/
>   };
>
> -static u8 *bq27xxx_regs[] = {
> +static u8 *bq27xxx_regs[] __maybe_unused = {
>   	[BQ27000] = bq27000_regs,
>   	[BQ27010] = bq27010_regs,
>   	[BQ27500] = bq27500_regs,
> @@ -991,7 +991,7 @@ static void bq27xxx_external_power_changed(struct power_supply *psy)
>   	schedule_delayed_work(&di->work, 0);
>   }
>
> -static int bq27xxx_powersupply_init(struct bq27xxx_device_info *di,
> +static int __maybe_unused bq27xxx_powersupply_init(struct bq27xxx_device_info *di,
>   				    const char *name)
>   {
>   	int ret;
> @@ -1026,7 +1026,7 @@ static int bq27xxx_powersupply_init(struct bq27xxx_device_info *di,
>   	return 0;
>   }
>
> -static void bq27xxx_powersupply_unregister(struct bq27xxx_device_info *di)
> +static void __maybe_unused bq27xxx_powersupply_unregister(struct bq27xxx_device_info *di)
>   {
>   	/*
>   	 * power_supply_unregister call bq27xxx_battery_get_property which
>

The current organization of this driver has caused a lot of problems like this,
it has been discussed that it should just be re-organized before. I went ahead
and finally did this, I'll push the patch here in a bit, should take care of this and
several other issues.
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