Re: [PATCH] gpiolib: fix allocation of mixed dynamic/static GPIOs

[Christophe Leroy <christophe.leroy@xxxxxxxxxx>]

Le 27/04/2023 à 00:03, Andreas Kemnade a écrit :
> [Vous ne recevez pas souvent de courriers de andreas@xxxxxxxxxxxx. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
> 
> 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.

Hum ....

Commit 7b61212f2a07 ("gpiolib: Get rid of ARCH_NR_GPIOS") was supposed 
to enforce dynamic allocation above GPIO_DYNAMIC_BASE already.

Can you describe what is going wrong exactly with the above commit ?

Thanks
Christophe

> 
> Seen on a GTA04 when omap-gpio (static) and twl-gpio (dynamic)
> raced.
> 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")
> Suggested-by: andy.shevchenko@xxxxxxxxx
> Signed-off-by: Andreas Kemnade <andreas@xxxxxxxxxxxx>
> ---
>   drivers/gpio/gpiolib.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 19bd23044b017..18b68d0aec7db 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -188,6 +188,10 @@ static int gpiochip_find_base(int ngpio)
>          int base = GPIO_DYNAMIC_BASE;
> 
>          list_for_each_entry(gdev, &gpio_devices, list) {
> +               /* do not pollute area for static allocation */
> +               if (gdev->base < GPIO_DYNAMIC_BASE)
> +                       continue;
> +
>                  /* found a free space? */
>                  if (gdev->base >= base + ngpio)
>                          break;
> --
> 2.39.2
>