linux-kernel - Re: [PATCH v2] regulator: wm8994: Don't use devres for enable GPIOs

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Date:   Wed, 21 Nov 2018 11:42:06 +0100
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Charles Keepax <ckeepax@...nsource.cirrus.com>, broonie@...nel.org
Cc:     linus.walleij@...aro.org, lgirdwood@...il.com,
        linux-kernel@...r.kernel.org, patches@...nsource.cirrus.com
Subject: Re: [PATCH v2] regulator: wm8994: Don't use devres for enable GPIOs

Hi Charles,

On 2018-11-21 11:13, Charles Keepax wrote:
> The regulator core takes over managing the lifetime of the enable GPIO
> once the regulator is registered. As such we shouldn't register the
> enable GPIO using devm, or it will be freed twice.
>
> Reported-by: Marek Szyprowski <m.szyprowski@...sung.com>
> Signed-off-by: Charles Keepax <ckeepax@...nsource.cirrus.com>
> ---
>
> Again only build tested.

Thanks for the patch. It fixes the observed GPIOlib warning.

Tested-by: Marek Szyprowski <m.szyprowski@...sung.com>

It might sense to add:

Fixes: 1d2f46814d20 ("regulator: wm8994: Pass descriptor instead of GPIO
number")


Linus, Mark: Similar issue is probably in the other regulator drivers,
which use enable GPIO allocated by devm_gpio_get*(). This driver is
simply the first one, which we observed it. It would be great if one
would take a look into regulator_register() error path, because for some
cases the GPIO will be freed, for the other - not.

> Thanks,
> Charles
>
>  drivers/regulator/wm8994-regulator.c | 14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/regulator/wm8994-regulator.c b/drivers/regulator/wm8994-regulator.c
> index d7fec533c4032..46e6b4ee1491a 100644
> --- a/drivers/regulator/wm8994-regulator.c
> +++ b/drivers/regulator/wm8994-regulator.c
> @@ -147,11 +147,14 @@ static int wm8994_ldo_probe(struct platform_device *pdev)
>  	config.regmap = wm8994->regmap;
>  	config.init_data = &ldo->init_data;
>  
> -	/* Look up LDO enable GPIO from the parent device node */
> -	gpiod = devm_gpiod_get_optional(pdev->dev.parent,
> -					id ? "wlf,ldo2ena" : "wlf,ldo1ena",
> -					GPIOD_OUT_LOW |
> -					GPIOD_FLAGS_BIT_NONEXCLUSIVE);
> +	/*
> +	 * Look up LDO enable GPIO from the parent device node, we don't
> +	 * use devm because the regulator core will free the GPIO
> +	 */
> +	gpiod = gpiod_get_optional(pdev->dev.parent,
> +				   id ? "wlf,ldo2ena" : "wlf,ldo1ena",
> +				   GPIOD_OUT_LOW |
> +				   GPIOD_FLAGS_BIT_NONEXCLUSIVE);
>  	if (IS_ERR(gpiod))
>  		return PTR_ERR(gpiod);
>  	config.ena_gpiod = gpiod;
> @@ -184,6 +187,7 @@ static int wm8994_ldo_probe(struct platform_device *pdev)
>  	return 0;
>  
>  err:
> +	gpiod_put(gpiod);
>  	return ret;
>  }
>  

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland