linux-kernel - Re: [PATCH 1/3] auxdisplay: Add 7 segment LED display driver

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Date: Mon, 26 Feb 2024 04:32:06 +0200
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Chris Packham <chris.packham@...iedtelesis.co.nz>
Cc: ojeda@...nel.org, robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org, 
	conor+dt@...nel.org, andrew@...n.ch, gregory.clement@...tlin.com, 
	sebastian.hesselbarth@...il.com, geert@...ux-m68k.org, pavel@....cz, 
	lee@...nel.org, devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-leds@...r.kernel.org
Subject: Re: [PATCH 1/3] auxdisplay: Add 7 segment LED display driver

On Sun, Feb 25, 2024 at 11:34 PM Chris Packham
<chris.packham@...iedtelesis.co.nz> wrote:
>
> Add a driver for a 7 segment LED display. At the moment only one
> character is supported but it should be possible to expand this to
> support more characters and/or 14 segment displays in the future.

(I try to comment only on the things that will remain after rebasing
on top of auxdisplay:for-next)

..

> +config SEG_LED
> +       bool "Generic 7 segment LED display"

Why can't it be a module?

> +       select LINEDISP
> +       help
> +         This driver supports a generic 7 segment LED display made up
> +         of GPIO pins connected to the individual segments.

Checkpatch wants 3+ lines of help, I would add the module name (after
changing it to be tristate, etc).

..

> + * The GPIOs are wired to the 7 segments in a clock wise fashion starting from

clockwise

> + * the top.

..

> + * The decimal point LED presnet on some devices is currently not

present

> + * supported.

..

> +#include <linux/gpio/consumer.h>
> +#include <linux/kernel.h>
> +#include <linux/map_to_7segment.h>
> +#include <linux/module.h>

> +#include <linux/of.h>

This is not used. And actually shouldn't be in a new code like this
with rare exceptions.

> +#include <linux/platform_device.h>

This is rather semirandom, please use IWYU (Include What You Use)
principle. We have, among others, container_of.h, types.h, err.h,
bitmap.h, mod_devicetable.h.

..

With

    sturct device *dev = &pdev->dev;

the below code will be neater.

> +       priv = devm_kzalloc(&pdev->dev, struct_size(priv, curr, 1), GFP_KERNEL);
> +       if (!priv)
> +               return -ENOMEM;
> +       priv->num_char = 1;
> +
> +       platform_set_drvdata(pdev, priv);
> +
> +       priv->segment_gpios = devm_gpiod_get_array(&pdev->dev, "segment", GPIOD_OUT_LOW);
> +       if (IS_ERR(priv->segment_gpios))
> +               return PTR_ERR(priv->segment_gpios);

..

> +static struct platform_driver seg_led_driver = {
> +       .probe = seg_led_probe,
> +       .remove = seg_led_remove,
> +       .driver = {
> +               .name = "seg-led",
> +               .of_match_table = seg_led_of_match,
> +       },
> +};

> +

Redundant blank line.

> +module_platform_driver(seg_led_driver);
> +
> +MODULE_AUTHOR("Chris Packham <chris.packham@...iedtelesis.co.nz>");
> +MODULE_DESCRIPTION("7 segment LED driver");
> +MODULE_LICENSE("GPL");

> +

Seems like a redundant blank line at the end of the file.

-- 
With Best Regards,
Andy Shevchenko