linux-kernel - Re: [PATCH 2/2] pinctrl: Add Cypress cy8c95x0 support

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Date:   Thu, 21 Apr 2022 22:53:02 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Patrick Rudolph <patrick.rudolph@...ements.com>
Cc:     Naresh Solanki <naresh.solanki@...ements.com>,
        linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org
Subject: Re: [PATCH 2/2] pinctrl: Add Cypress cy8c95x0 support

Hi Patrick, Naresh,

thanks for your patch! This is a VERY good looking driver so I don't
think we will need a lot of iterations before it is finished. (Famous
last words, but it looks very good.)

On Tue, Apr 19, 2022 at 9:17 AM Patrick Rudolph
<patrick.rudolph@...ements.com> wrote:

> +static const struct i2c_device_id cy8c95x0_id[] = {
> +       { "cy8c9520", 20, },
> +       { "cy8c9540", 40, },
> +       { "cy8c9560", 60, },
> +       { }

So here is the ngpios for each expander.

> +       chip->tpin = chip->driver_data & CY8C95X0_GPIO_MASK;
> +       ngpios = -1;
> +       if (client->dev.of_node)
> +               of_property_read_u32(client->dev.of_node, "ngpios", &ngpios);
> +
> +       if (ngpios < 0 || ngpios > (chip->driver_data & CY8C95X0_GPIO_MASK))
> +               ngpios = chip->driver_data & CY8C95X0_GPIO_MASK;

So why should this be configurable from the device tree at all?

I understand if not all gpios are used, but we usually just expose all
GPIOs on an expander.

Yours,
Linus Walleij