linux-kernel - Re: [PATCH 09/15] gpio: support ROHM BD71815 GPOs

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Date:   Sat, 9 Jan 2021 01:45:50 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Matti Vaittinen <matti.vaittinen@...rohmeurope.com>
Cc:     Matti Vaittinen <mazziesaccount@...il.com>,
        Lee Jones <lee.jones@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-power@...rohmeurope.com,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>
Subject: Re: [PATCH 09/15] gpio: support ROHM BD71815 GPOs

On Fri, Jan 8, 2021 at 2:39 PM Matti Vaittinen
<matti.vaittinen@...rohmeurope.com> wrote:

> Support GPO(s) found from ROHM BD71815 power management IC. The IC has two
> GPO pins but only one is properly documented in data-sheet. The driver
> exposes by default only the documented GPO. The second GPO is connected to
> E5 pin and is marked as GND in data-sheet. Control for this undocumented
> pin can be enabled using a special DT property.
>
> This driver is derived from work by Peter Yang <yanglsh@...est-tech.com>
> although not so much of original is left.
>
> Signed-off-by: Matti Vaittinen <matti.vaittinen@...rohmeurope.com>

Overall this looks good!

> +       depends on MFD_ROHM_BD71828

I suppose this makes i possible to merge out-of-order with the
core patches actually.

> +#define DEBUG

Why? Development artifact?

> +#include <linux/kthread.h>

You certainly do not need this.

> +#include <linux/mfd/rohm-bd71815.h>
> +#include <linux/mfd/rohm-generic.h>

I guess registers come from these? Do you need both?
Add a comment about what they provide.

> +       g->chip.ngpio = 1;
> +       if (g->e5_pin_is_gpo)
> +               g->chip.ngpio = 2;

Overwriting value, how not elegant.

if (g->e5_pin_is_gpo)
  g->chip.ngpio = 2;
else
  g->chip.ngpio = 1;

> +       g->chip.parent = pdev->dev.parent;
> +       g->chip.of_node = pdev->dev.parent->of_node;
> +       g->regmap = dev_get_regmap(pdev->dev.parent, NULL);
> +       g->dev = &pdev->dev;
> +
> +       ret = devm_gpiochip_add_data(&pdev->dev, &g->chip, g);
> +       if (ret < 0) {
> +               dev_err(&pdev->dev, "could not register gpiochip, %d\n", ret);
> +               return ret;
> +       }

It's a bit confusing how you use pdev->dev.parent for some stuff
and &pdev->dev for some.

What about assinging

struct device *dev = pdev->dev.parent;

and use dev for all the calls, it looks like it'd work fine.

Yours,
Linus Walleij