linux-kernel - Re: [PATCH 1/4] gpio-f7188x: Add GPIO support for Nuvoton NCT6116

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Date:   Thu, 28 Jul 2022 23:33:36 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Henning Schild <henning.schild@...mens.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Linus Walleij <linus.walleij@...aro.org>,
        Tasanakorn Phaipool <tasanakorn@...il.com>,
        Sheng-Yuan Huang <syhuang3@...oton.com>,
        Kuan-Wei Ho <cwho@...oton.com>
Subject: Re: [PATCH 1/4] gpio-f7188x: Add GPIO support for Nuvoton NCT6116

On Thu, Jul 28, 2022 at 5:57 PM Henning Schild
<henning.schild@...mens.com> wrote:
>
> Add GPIO support for Nuvoton NCT6116 chip. Nuvoton SuperIO chips are
> very similar to the ones from Fintek. In other subsystems they also
> share drivers and are called a family of drivers.
>
> For the GPIO subsystem the only difference is that the direction bit is
> reversed and that there is only one data bit per pin. On the SuperIO
> level the logical device is another one.

...

> +#define SIO_GPIO_ENABLE                0x30    /* GPIO enable */

I don't see how it's being utilized... (But okay, it might be good to
have as a hint for a reader who has no access to the documentation).

...

> +       if (sio->device == SIO_LD_GPIO_NUVOTON) {

Everywhere else you use `device == SIO_LD_GPIO_FINTEK`, perhaps here
for consistency? However, I would rather see a field that clearly
states that it's an inverted value. Then you can use

  if (sio->dir_inv)
    ...do something...

> +               if (dir & BIT(offset))
> +                       return GPIO_LINE_DIRECTION_IN;
> +
> +               return GPIO_LINE_DIRECTION_OUT;
> +       }
> +
> +       if (dir & BIT(offset))
>                 return GPIO_LINE_DIRECTION_OUT;
>
>         return GPIO_LINE_DIRECTION_IN;

-- 
With Best Regards,
Andy Shevchenko