linux-kernel - Re: [PATCH v2] gpio: pca953x: add support for open drain pins on PCAL6524

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Date:   Mon, 15 Feb 2021 14:53:46 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Alban Bedel <alban.bedel@...q.com>
Cc:     "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] gpio: pca953x: add support for open drain pins on PCAL6524

Hint: don't forget to include reviewers from previous version

On Thu, Feb 11, 2021 at 7:52 PM Alban Bedel <alban.bedel@...q.com> wrote:
>
> From a quick glance at various datasheets the PCAL6524 and the
> PCAL6534 seems to be the only chips in this family that support
> setting the drive mode of single pins. Other chips either don't
> support it at all, or can only set the drive mode of whole banks,
> which doesn't map to the GPIO API.
>
> Add a new flag, PCAL65xx_REGS, to mark chips that have the extra
> registers needed for this feature. Then mark the needed register banks
> as readable and writable, here we don't set OUT_CONF as writable,
> although it is, as we only need to read it. Finally add a function
> that configures the OUT_INDCONF register when the GPIO API sets the
> drive mode of the pins.

...

> +#define PCAL65xx_REGS          BIT(10)

Can we have it as a _TYPE, please?

...

> +#define PCAL65xx_BANK_INDOUT_CONF BIT(8 + 12)

IND is a bit ambiguous based on the description below.
After you elaborate, I probably can propose better naming.

...

> + *   - PCAL65xx with individual pin configuration
> + *     Individual pin output config    0x40 + 12 * bank_size   RW

Not sure I understand what "individual" means here (no, I haven't
looked into the datasheet).

...

> +       if (config == PIN_CONFIG_DRIVE_OPEN_DRAIN)
> +               val = mask;
> +       else if (config == PIN_CONFIG_DRIVE_PUSH_PULL)
> +               val = 0;
> +       else
> +               return -EINVAL;

Switch-case will look more naturally here (despite being longer in
terms of LOCs).

...

> +exit:

exit_unlock:

> +       mutex_unlock(&chip->i2c_lock);
> +       return ret;

...

> +#define OF_L65XX(__nrgpio) OF_953X(__nrgpio, PCA_LATCH_INT | PCAL65xx_REGS)

When you change to the type, it will go accordingly. Don't add
LATCH_INT to the macro.

-- 
With Best Regards,
Andy Shevchenko