linux-kernel - Re: [PATCH v2 2/2] gpio: ds4520: Add ADI DS4520 GPIO Expander Support

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Date:   Tue, 2 May 2023 18:55:04 +0300
From:   andy.shevchenko@...il.com
To:     Okan Sahin <okan.sahin@...log.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        linux-gpio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] gpio: ds4520: Add ADI DS4520 GPIO Expander Support

Tue, May 02, 2023 at 02:05:16AM +0300, Okan Sahin kirjoitti:
> The DS4520 is a 9-bit nonvolatile (NV) I/O expander.
> It offers users a digitally programmable alternative
> to hardware jumpers and mechanical switches that are
> being used to control digital logic node.

...

> +#include <linux/device.h>
> +#include <linux/gpio/driver.h>
> +#include <linux/gpio/regmap.h>
> +#include <linux/i2c.h>

Missing property.h.

> +#include <linux/regmap.h>

...

> +#define NUMBER_OF_GPIO	9
> +
> +#define PULLUP0		0xF0
> +#define IO_CONTROL0	0xF2
> +#define IO_STATUS0	0xF8

No namespace for the above?

...

> +	struct gpio_regmap_config config = {0};

0 is not needed.

> +	ngpio = NUMBER_OF_GPIO;

Do you really need this? Can Device Tree be sufficient here? (We have a
GPIO-wide property for that).

...

> +	ret = device_property_read_u32(dev, "reg", &base);
> +	if (ret)
> +		return -EINVAL;

Why shadowing error?

...

> +	regmap = devm_regmap_init_i2c(client, &ds4520_regmap_config);
> +	if (IS_ERR(regmap)) {

> +		ret = PTR_ERR(regmap);
> +		dev_err_probe(dev, ret,
> +			      "Failed to allocate register map\n");
> +		return ret;

	return dev_err_probe();

> +	}

...

> +	config.ngpio = ngpio;

Why do you use temporary variable ngpio and not assign directly here?

-- 
With Best Regards,
Andy Shevchenko