linux-kernel - Re: [PATCH] pinctrl: at91: allow use of of gpio-line-names property

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Date:   Wed, 8 Dec 2021 13:33:25 +0100
From:   Alexander Dahl <ada@...rsis.com>
To:     Peter Rosin <peda@...ntia.se>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Ludovic Desroches <ludovic.desroches@...rochip.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>
Subject: Re: [PATCH] pinctrl: at91: allow use of of gpio-line-names property

Hello Peter,

Am Tue, Dec 07, 2021 at 12:32:03AM +0100 schrieb Peter Rosin:
> If no line name is given (by not having a gpio-line-names property,
> or by having empty "" strings for some lines), fall back to the
> existing pioC12-style line name scheme.
> 
> It is useful to be able to explicitly name lines from the schematics
> or its function, rather than having the MCU names forced upon every
> user.

+1 from me. 

I asked about this some months ago, but I saw no clear
direction in the discussion. So for reference:

https://lore.kernel.org/linux-gpio/946021874.11132.1615900079722@seven.thorsis.com/

HTH & Greets
Alex

> Signed-off-by: Peter Rosin <peda@...ntia.se>
> ---
>  drivers/pinctrl/pinctrl-at91.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> I don't know if it's sane to fall back to the pioC12-style on empty
> strings, or if someone adding a gpio-line-names property should be
> responsible for filling in those names "by hand". I generally don't
> care what "unused" pins are named, so either is fine by me...
> 
> Cheers,
> Peter
> 
> diff --git a/drivers/pinctrl/pinctrl-at91.c b/drivers/pinctrl/pinctrl-at91.c
> index 6022496bb6a9..4f108d07e6ad 100644
> --- a/drivers/pinctrl/pinctrl-at91.c
> +++ b/drivers/pinctrl/pinctrl-at91.c
> @@ -1821,7 +1821,7 @@ static int at91_gpio_probe(struct platform_device *pdev)
>  	int irq, i;
>  	int alias_idx = of_alias_get_id(np, "gpio");
>  	uint32_t ngpio;
> -	char **names;
> +	const char **names;
>  
>  	BUG_ON(alias_idx >= ARRAY_SIZE(gpio_chips));
>  	if (gpio_chips[alias_idx]) {
> @@ -1890,8 +1890,15 @@ static int at91_gpio_probe(struct platform_device *pdev)
>  		goto clk_enable_err;
>  	}
>  
> -	for (i = 0; i < chip->ngpio; i++)
> -		names[i] = kasprintf(GFP_KERNEL, "pio%c%d", alias_idx + 'A', i);
> +	if (of_property_read_string_array(np, "gpio-line-names",
> +					  names, chip->ngpio) != chip->ngpio)
> +		memset(names, 0, chip->ngpio * sizeof(char *));
> +
> +	for (i = 0; i < chip->ngpio; i++) {
> +		if (!names[i] || !names[i][0])
> +			names[i] = kasprintf(GFP_KERNEL,
> +					     "pio%c%d", alias_idx + 'A', i);
> +	}
>  
>  	chip->names = (const char *const *)names;
>  
> -- 
> 2.20.1
>