linux-kernel - Re: [PATCH v2] gpiolib: fix allocation of mixed dynamic/static GPIOs

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Message-ID: <c4c26104-80a0-ceff-bf06-0a02813acbfc@csgroup.eu>
Date:   Sat, 29 Apr 2023 06:23:25 +0000
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Andreas Kemnade <andreas@...nade.info>,
        "linus.walleij@...aro.org" <linus.walleij@...aro.org>,
        "brgl@...ev.pl" <brgl@...ev.pl>,
        "andy.shevchenko@...il.com" <andy.shevchenko@...il.com>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Tony Lindgren <tony@...mide.com>,
        Aaro Koskinen <aaro.koskinen@....fi>,
        "linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>
Subject: Re: [PATCH v2] gpiolib: fix allocation of mixed dynamic/static GPIOs



Le 28/04/2023 à 21:45, Andreas Kemnade a écrit :
> If static allocation and dynamic allocation GPIOs are present,
> dynamic allocation pollutes the numberspace for static allocation,
> causing static allocation to fail.
> Enfore dynamic allocation above GPIO_DYNAMIC_BASE.
> 
> Seen on a GTA04 when omap-gpio (static) and twl-gpio (dynamic)
> raced:
> [some successful registrations of omap_gpio instances]
> [    2.553833] twl4030_gpio twl4030-gpio: gpio (irq 145) chaining IRQs 161..178
> [    2.561401] gpiochip_find_base: found new base at 160
> [    2.564392] gpio gpiochip5: (twl4030): added GPIO chardev (254:5)
> [    2.564544] gpio gpiochip5: registered GPIOs 160 to 177 on twl4030
> [...]
> [    2.692169] omap-gpmc 6e000000.gpmc: GPMC revision 5.0
> [    2.697357] gpmc_mem_init: disabling cs 0 mapped at 0x0-0x1000000
> [    2.703643] gpiochip_find_base: found new base at 178
> [    2.704376] gpio gpiochip6: (omap-gpmc): added GPIO chardev (254:6)
> [    2.704589] gpio gpiochip6: registered GPIOs 178 to 181 on omap-gpmc
> [...]
> [    2.840393] gpio gpiochip7: Static allocation of GPIO base is deprecated, use dynamic allocation.
> [    2.849365] gpio gpiochip7: (gpio-160-191): GPIO integer space overlap, cannot add chip
> [    2.857513] gpiochip_add_data_with_key: GPIOs 160..191 (gpio-160-191) failed to register, -16
> [    2.866149] omap_gpio 48310000.gpio: error -EBUSY: Could not register gpio chip
> 
> On that device it is fixed invasively by
> commit 92bf78b33b0b4 ("gpio: omap: use dynamic allocation of base")
> but lets also fix that for devices where there is still
> a mixture of static and dynamic allocation.
> 
> Fixes: 7b61212f2a07 ("gpiolib: Get rid of ARCH_NR_GPIOS")
> Signed-off-by: Andreas Kemnade <andreas@...nade.info>

Reviewed-by: <christophe.leroy@...roup.eu>

> ---
> Changes in V2:
>     handle also the case of overlapping static allocation
>     across DYNAMIC_BASE
> 
>   drivers/gpio/gpiolib.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 19bd23044b017..4472214fcd43a 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -193,6 +193,8 @@ static int gpiochip_find_base(int ngpio)
>   			break;
>   		/* nope, check the space right after the chip */
>   		base = gdev->base + gdev->ngpio;
> +		if (base < GPIO_DYNAMIC_BASE)
> +			base = GPIO_DYNAMIC_BASE;
>   	}
>   
>   	if (gpio_is_valid(base)) {