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References: <20230428194541.510674-1-andreas@kemnade.info>
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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Sat, 29 Apr 2023 14:10:46 +0300
Message-ID: <CAHp75Vfv5kO2q+xF6=fRMfMsM3xajfRs8iR10d06dfogBfYAOg@mail.gmail.com>
Subject: Re: [PATCH v2] gpiolib: fix allocation of mixed dynamic/static GPIOs
To:     Andreas Kemnade <andreas@kemnade.info>
Cc:     linus.walleij@linaro.org, brgl@bgdev.pl,
        christophe.leroy@csgroup.eu, linux-gpio@vger.kernel.org,
        linux-kernel@vger.kernel.org, Tony Lindgren <tony@atomide.com>,
        Aaro Koskinen <aaro.koskinen@iki.fi>,
        linux-omap@vger.kernel.org
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On Fri, Apr 28, 2023 at 10:45=E2=80=AFPM Andreas Kemnade <andreas@kemnade.i=
nfo> wrote:
>
> 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.

Enforce

> 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 16=
1..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 deprecat=
ed, 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

let's

> a mixture of static and dynamic allocation.

It might be that it can be optimized, but OK for now. Thanks for fixing it.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> Fixes: 7b61212f2a07 ("gpiolib: Get rid of ARCH_NR_GPIOS")
> Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
> ---
> 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 =3D gdev->base + gdev->ngpio;
> +               if (base < GPIO_DYNAMIC_BASE)
> +                       base =3D GPIO_DYNAMIC_BASE;
>         }
>
>         if (gpio_is_valid(base)) {
> --
> 2.39.2
>


--=20
With Best Regards,
Andy Shevchenko