linux-kernel - Re: [PATCH 2/3] regulator: Only free GPIOs if the core requested them

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Message-ID: <0716cd43-2f2d-cac9-5bb7-dffcbd3a4795@samsung.com>
Date:   Fri, 23 Nov 2018 10:24:46 +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 2/3] regulator: Only free GPIOs if the core requested
 them

Hi Charles,

On 2018-11-22 18:30, Charles Keepax wrote:
> Currently, the regulator core will take ownership of any GPIO passed
> into it. Makes end driver code fairly error prone as the normal devm_
> patterns of allocation don't work. Update the regulator core to only
> free the GPIO if it requested it, this allows the drivers to manage the
> GPIO lifetime as they normally would.
>
> Reported-by: Marek Szyprowski <m.szyprowski@...sung.com>
> Signed-off-by: Charles Keepax <ckeepax@...nsource.cirrus.com>

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

> ---
>  drivers/regulator/core.c | 19 +++++++++++--------
>  1 file changed, 11 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
> index dbe2f2e6e6254..9da7d27c7145e 100644
> --- a/drivers/regulator/core.c
> +++ b/drivers/regulator/core.c
> @@ -83,6 +83,7 @@ struct regulator_enable_gpio {
>  	u32 enable_count;	/* a number of enabled shared GPIO */
>  	u32 request_count;	/* a number of requested shared GPIO */
>  	unsigned int ena_gpio_invert:1;
> +	unsigned int locally_requested:1;
>  };
>  
>  /*
> @@ -2233,19 +2234,20 @@ static int regulator_ena_gpio_request(struct regulator_dev *rdev,
>  		}
>  	}
>  
> +	pin = kzalloc(sizeof(struct regulator_enable_gpio), GFP_KERNEL);
> +	if (pin == NULL)
> +		return -ENOMEM;
> +
>  	if (!config->ena_gpiod) {
>  		ret = gpio_request_one(config->ena_gpio,
>  				       GPIOF_DIR_OUT | config->ena_gpio_flags,
>  				       rdev_get_name(rdev));
> -		if (ret)
> +		if (ret) {
> +			kfree(pin);
>  			return ret;
> -	}
> +		}
>  
> -	pin = kzalloc(sizeof(struct regulator_enable_gpio), GFP_KERNEL);
> -	if (pin == NULL) {
> -		if (!config->ena_gpiod)
> -			gpio_free(config->ena_gpio);
> -		return -ENOMEM;
> +		pin->locally_requested = 1;
>  	}
>  
>  	pin->gpiod = gpiod;
> @@ -2270,7 +2272,8 @@ static void regulator_ena_gpio_free(struct regulator_dev *rdev)
>  		if (pin->gpiod == rdev->ena_pin->gpiod) {
>  			if (pin->request_count <= 1) {
>  				pin->request_count = 0;
> -				gpiod_put(pin->gpiod);
> +				if (pin->locally_requested)
> +					gpiod_put(pin->gpiod);
>  				list_del(&pin->list);
>  				kfree(pin);
>  				rdev->ena_pin = NULL;

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