linux-kernel - Re: [PATCH v5 8/9] pinctrl: axp209: add support for AXP813 GPIOs

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Date:   Fri, 8 Dec 2017 14:41:37 +0100
From:   Quentin Schulz <quentin.schulz@...e-electrons.com>
To:     linus.walleij@...aro.org, robh+dt@...nel.org, mark.rutland@....com,
        wens@...e.org, linux@...linux.org.uk,
        maxime.ripard@...e-electrons.com, lee.jones@...aro.org
Cc:     linux-gpio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        thomas.petazzoni@...e-electrons.com, linux-sunxi@...glegroups.com
Subject: Re: [PATCH v5 8/9] pinctrl: axp209: add support for AXP813 GPIOs

Hi all,

There is a bug below.

On 05/12/2017 15:46, Quentin Schulz wrote:
> The AXP813 has only two GPIOs. GPIO0 can either be used as a GPIO, an
> LDO regulator or an ADC. GPIO1 can be used either as a GPIO or an LDO
> regulator.
> 
> Moreover, the status bit of the GPIOs when in input mode is not offset
> by 4 unlike the AXP209.
> 
> Signed-off-by: Quentin Schulz <quentin.schulz@...e-electrons.com>
> Acked-by: Maxime Ripard <maxime.ripard@...e-electrons.com>
> Acked-by: Rob Herring <robh@...nel.org>
[...]

>  static int axp20x_pctl_probe(struct platform_device *pdev)
>  {
>  	struct axp20x_dev *axp20x = dev_get_drvdata(pdev->dev.parent);
>  	struct axp20x_pctl *pctl;
> +	struct device *dev = &pdev->dev;
>  	struct pinctrl_desc *pctrl_desc;
>  	int ret;
>  
> @@ -388,9 +413,9 @@ static int axp20x_pctl_probe(struct platform_device *pdev)
>  	pctl->chip.set			= axp20x_gpio_set;
>  	pctl->chip.direction_input	= axp20x_gpio_input;
>  	pctl->chip.direction_output	= axp20x_gpio_output;
> -	pctl->chip.ngpio		= 3;
> +	pctl->chip.ngpio		= pctl->desc->npins;
>  
> -	pctl->desc = &axp20x_data;
> +	pctl->desc = (struct axp20x_pctrl_desc *)of_device_get_match_data(dev);
>  	pctl->regmap = axp20x->regmap;
>  	pctl->dev = &pdev->dev;
>  

I am using pctl->desc before retrieving it, thus dereferencing from a
null pointer.

We just have to move
pctl->chip.ngpio		= pctl->desc->npins;
after
pctl->desc = (struct axp20x_pctrl_desc *)of_device_get_match_data(dev);

Linus, I guess that I should send a patch to fix this or is there an
other way not to have to apply such a small and dumb patch?

Quentin
-- 
Quentin Schulz, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com