linux-kernel - Re: [PATCH 2/5] i2c-mux-gpio: Return an error if no config data found

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Date:   Wed, 24 Apr 2019 21:25:50 +0000
From:   Peter Rosin <peda@...ntia.se>
To:     Serge Semin <fancer.lancer@...il.com>,
        Peter Korsgaard <peter.korsgaard@...co.com>
CC:     Serge Semin <Sergey.Semin@...latforms.ru>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/5] i2c-mux-gpio: Return an error if no config data found

On 2019-04-24 14:34, Serge Semin wrote:
> It's pointless and might be even errors prone to proceed with further
> initialization if neither of- no platform-based settings were discovered.
> Just return an error in this case.
> 
> Signed-off-by: Serge Semin <fancer.lancer@...il.com>
> ---
>  drivers/i2c/muxes/i2c-mux-gpio.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/i2c/muxes/i2c-mux-gpio.c b/drivers/i2c/muxes/i2c-mux-gpio.c
> index 24cf6ec02e75..a14fe132b0c3 100644
> --- a/drivers/i2c/muxes/i2c-mux-gpio.c
> +++ b/drivers/i2c/muxes/i2c-mux-gpio.c
> @@ -132,7 +132,7 @@ static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
>  static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
>  					struct platform_device *pdev)
>  {
> -	return 0;
> +	return -EINVAL;
>  }
>  #endif
>  
> @@ -142,6 +142,9 @@ static int i2c_mux_gpio_probe_plat(struct gpiomux *mux,
>  	struct i2c_mux_gpio_platform_data *data = dev_get_platdata(&pdev->dev);
>  	struct gpio_chip *gpio;
>  
> +	if (!data)
> +		return -EINVAL;
> +
>  	/*
>  	 * If a GPIO chip name is provided, the GPIO pin numbers provided are
>  	 * relative to its base GPIO number. Otherwise they are absolute.
> @@ -175,11 +178,10 @@ static int i2c_mux_gpio_probe(struct platform_device *pdev)
>  	if (!mux)
>  		return -ENOMEM;
>  
> -	if (!dev_get_platdata(&pdev->dev))
> +	ret = i2c_mux_gpio_probe_plat(mux, pdev);
> +	if (ret)
>  		ret = i2c_mux_gpio_probe_dt(mux, pdev);
> -	else
> -		ret = i2c_mux_gpio_probe_plat(mux, pdev);
> -	if (ret < 0)
> +	if (ret)
>  		return ret;

I notice that after this patch, all probe failures from non-dt configs
will return -EINVAL from the dummy i2c_mux_gpio_probe_dt that gets
called on i2c_mux_gpio_probe_plat failure.

So, any -EPROBE_DEFER is now lost. That probably doesn't fly.

Cheers,
Peter

>  
>  	parent = i2c_get_adapter(mux->data.parent);
>