linux-kernel - Re: [PATCH v3 1/7] gpio: gpio-ep93xx: fix BUG

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Date:   Thu, 28 Jan 2021 17:19:45 +0100
From:   Alexander Sverdlin <alexander.sverdlin@...il.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Nikita Shubin <nikita.shubin@...uefel.me>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 1/7] gpio: gpio-ep93xx: fix BUG_ON port F usage

Hello Nikita,

On Thu, 2021-01-28 at 18:11 +0200, Andy Shevchenko wrote:
> > +/*
> > + * F Port index in GPIOCHIP'S array is 5
> > + * but we use index 2 for stored values and offsets
> > + */
> > +#define EP93XX_GPIO_F_PORT_INDEX 5
> 
> Hmm... Why not to use an array with holes instead.
> 
> ...
> 
> > +       if (port == EP93XX_GPIO_F_PORT_INDEX)
> > +               port = 2;
> 
> Sorry, but I'm not in favour of this as it adds confusion.
> See above for the potential way to solve.

well, I was thinking the same yesterday. It just adds another
level on confusion into the code, which even the author got
wrong :)

Array with holes would be more obvious, but one can also embedd
the necessary values into struct ep93xx_gpio_bank.

-- 
Alexander Sverdlin.