linux-kernel - Re: [PATCH] extcon: gpio: Request gpio pin before modifying its state

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Date:	Mon, 25 Nov 2013 02:37:13 +0000 (GMT)
From:	MyungJoo Ham <myungjoo.ham@...sung.com>
To:	Guenter Roeck <linux@...ck-us.net>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc:	최찬우 <cw00.choi@...sung.com>
Subject: Re: [PATCH] extcon: gpio: Request gpio pin before modifying its state

> Commit 338de0ca (extcon: gpio: Use gpio driver/chip debounce if supported)
> introduced a call to gpio_set_debounce() before actually requesting the
> respective gpio pin from the gpio subsystem.
> 
> The gpio subsystem expects that a gpio pin was requested before modifying its
> state. Not doing so results in a warning from gpiolib, and the gpio pin is
> auto-requested. This in turn causes the subsequent devm_gpio_request_one()
> to fail. So devm_gpio_request_one() must be called prior to calling
> gpio_set_debounce().
> 
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>

Thank you.


Acked-by: MyungJoo Ham <myungjoo.ham@...sung.com>

> ---
>  drivers/extcon/extcon-gpio.c |   11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/extcon/extcon-gpio.c b/drivers/extcon/extcon-gpio.c
> index 7e0dff5..4736a9c 100644
> --- a/drivers/extcon/extcon-gpio.c
> +++ b/drivers/extcon/extcon-gpio.c
> @@ -105,6 +105,12 @@ static int gpio_extcon_probe(struct platform_device *pdev)
>  	extcon_data->state_off = pdata->state_off;
>  	if (pdata->state_on && pdata->state_off)
>  		extcon_data->edev.print_state = extcon_gpio_print_state;
> +
> +	ret = devm_gpio_request_one(&pdev->dev, extcon_data->gpio, GPIOF_DIR_IN,
> +				    pdev->name);
> +	if (ret < 0)
> +		return ret;
> +
>  	if (pdata->debounce) {
>  		ret = gpio_set_debounce(extcon_data->gpio,
>  					pdata->debounce * 1000);
> @@ -117,11 +123,6 @@ static int gpio_extcon_probe(struct platform_device *pdev)
>  	if (ret < 0)
>  		return ret;
>  
> -	ret = devm_gpio_request_one(&pdev->dev, extcon_data->gpio, GPIOF_DIR_IN,
> -				    pdev->name);
> -	if (ret < 0)
> -		goto err;
> -
>  	INIT_DELAYED_WORK(&extcon_data->work, gpio_extcon_work);
>  
>  	extcon_data->irq = gpio_to_irq(extcon_data->gpio);
> -- 
> 1.7.9.7
> 
>