linux-kernel - Re: [PATCH] gpio: mxs: use dynamic allocation of base

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Message-ID: <33714d4c-31a9-527c-f80a-1f51c9a37f98@i2se.com>
Date:   Mon, 27 Feb 2023 18:52:19 +0100
From:   Stefan Wahren <stefan.wahren@...e.com>
To:     Dario Binacchi <dario.binacchi@...rulasolutions.com>,
        linux-kernel@...r.kernel.org
Cc:     Bartosz Golaszewski <brgl@...ev.pl>,
        Fabio Estevam <festevam@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        NXP Linux Team <linux-imx@....com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Shawn Guo <shawnguo@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-gpio@...r.kernel.org
Subject: Re: [PATCH] gpio: mxs: use dynamic allocation of base

Hi Dario,

Am 26.02.23 um 21:53 schrieb Dario Binacchi:
> Since commit 502df79b860563d7 ("gpiolib: Warn on drivers still using static
> gpiobase allocation"), one or more warnings are printed during boot on
> systems where static allocation of GPIO base is used:
>
> [    0.136834] gpio gpiochip0: Static allocation of GPIO base is deprecated, use dynamic allocation.
> [    0.142753] gpio gpiochip1: Static allocation of GPIO base is deprecated, use dynamic allocation.
> [    0.148452] gpio gpiochip2: Static allocation of GPIO base is deprecated, use dynamic allocation.
> [    0.154341] gpio gpiochip3: Static allocation of GPIO base is deprecated, use dynamic allocation.
> [    0.160097] gpio gpiochip4: Static allocation of GPIO base is deprecated, use dynamic allocation.
>
> So let's follow the suggestion and use dynamic allocation.

i understand the motivation of avoiding these warnings.

AFAIK the MXS platform is older than the dynamic allocation of GPIO 
base. In the perfect world all applications has been migrated to 
libgpiod / chardev GPIO. But i'm really concerned this hasn't happend 
yet, at least for this platform. So i believe this change break 
applications, since it affects userspace.

Best regards

>
> Signed-off-by: Dario Binacchi <dario.binacchi@...rulasolutions.com>
> ---
>
>   drivers/gpio/gpio-mxs.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpio-mxs.c b/drivers/gpio/gpio-mxs.c
> index 7f59e5d936c2..b48a7c1fb7c1 100644
> --- a/drivers/gpio/gpio-mxs.c
> +++ b/drivers/gpio/gpio-mxs.c
> @@ -330,7 +330,7 @@ static int mxs_gpio_probe(struct platform_device *pdev)
>   
>   	port->gc.to_irq = mxs_gpio_to_irq;
>   	port->gc.get_direction = mxs_gpio_get_direction;
> -	port->gc.base = port->id * 32;
> +	port->gc.base = -1;
>   
>   	err = gpiochip_add_data(&port->gc, port);
>   	if (err)