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Date: Tue, 11 Jun 2024 11:21:30 +0200
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Subject: Re: [PATCH V2 2/2] leds: add mp3326 driver
To: Yuxi Wang <Yuxi.Wang@monolithicpower.com>, pavel@ucw.cz, lee@kernel.org,
 robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org,
 wyx137120466@gmail.com
Cc: linux-leds@vger.kernel.org, devicetree@vger.kernel.org,
 linux-kernel@vger.kernel.org
References: <20240611083236.1609-1-Yuxi.Wang@monolithicpower.com>
 <20240611083236.1609-3-Yuxi.Wang@monolithicpower.com>
From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
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In-Reply-To: <20240611083236.1609-3-Yuxi.Wang@monolithicpower.com>
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On 11/06/2024 10:32, Yuxi Wang wrote:
> This commit adds support for MPS MP3326 LED driver.

Please do not use "This commit/patch/change", but imperative mood. See
longer explanation here:
https://elixir.bootlin.com/linux/v5.17.1/source/Documentation/process/submitting-patches.rst#L95

> 
> Signed-off-by: Yuxi Wang <Yuxi.Wang@monolithicpower.com>
> 
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index d721b254e1e4..3ca7be35c834 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig


> +/*
> + * PWM in the range of [0 255]
> + */
> +static int led_pwm_store(struct device *dev, struct device_attribute *attr,
> +			     const char *buf, size_t count)

Nope.

...

> +	}
> +	r_val = r_val * 255 / 4095 + (r_val * 255 % 4095) / (4095 / 2);
> +	g_val = g_val * 255 / 4095 + (g_val * 255 % 4095) / (4095 / 2);
> +	b_val = b_val * 255 / 4095 + (b_val * 255 % 4095) / (4095 / 2);
> +	if (led->num_colors == 1)
> +		return sysfs_emit(buf, "0x%x\n", r_val);
> +	else
> +		return sysfs_emit(buf, "0x%x 0x%x 0x%x\n", r_val, g_val, b_val);
> +}
> +
> +static int led_enable_store(struct device *dev,
> +				struct device_attribute *attr, const char *buf,
> +				size_t count)

Eeeee? store to enable LED? Really?

...

> +{
> +	struct led_classdev *lcdev = dev_get_drvdata(dev);
> +	struct mp3326_led *led = container_of(lcdev, struct mp3326_led, cdev);
> +	struct mp3326 *chip = led->private_data;
> +	int ret;
> +	uint val, i;


> +
> +static DEVICE_ATTR_RW(led_pwm);
> +static DEVICE_ATTR_RW(led_enable);
> +static DEVICE_ATTR_RO(led_short_fault);
> +static DEVICE_ATTR_RO(led_open_fault);

No, for multiple reasons:
1. Where ABI documentation?
2. There is a standard sysfs interface. No need for most of that. Please
explain why standard interface does not fit your needs - for each new
interface.

> +
> +static struct attribute *led_sysfs_attrs[] = {
> +	&dev_attr_led_pwm.attr,
> +	&dev_attr_led_enable.attr,
> +	&dev_attr_led_short_fault.attr,
> +	&dev_attr_led_open_fault.attr,
> +	NULL,
> +};
> +
> +ATTRIBUTE_GROUPS(led_sysfs);
> +
> +static int mp3326_add_led(struct mp3326 *chip, struct device_node *np,
> +			  int index)
> +{
> +	struct mp3326_led *led = &chip->leds[index];
> +	struct mc_subled *info;
> +	struct device_node *child;
> +	struct led_classdev *cdev;
> +	struct led_init_data init_data = {};
> +	int ret;
> +	int i = 0;
> +	int count;
> +	u32 color = 0;
> +	u32 reg = 0;
> +
> +	ret = of_property_read_u32(np, "color", &color);
> +	if (ret) {
> +		dev_err(&chip->client->dev, "Miss color in the node\n");
> +		return ret;
> +	}

Blank line

> +	led->private_data = chip;
> +	if (color == LED_COLOR_ID_RGB) {
> +		count = of_get_child_count(np);
> +		if (count != 3) {
> +			dev_err(&chip->client->dev,
> +				"RGB must have three node.\n");
> +			return -EINVAL;
> +		}
> +
> +		info = devm_kcalloc(&chip->client->dev, 3, sizeof(*info),
> +				    GFP_KERNEL);
> +		if (!info)
> +			return -ENOMEM;
> +
> +		for_each_available_child_of_node(np, child) {
> +			ret = of_property_read_u32(child, "reg", &reg);
> +			if (ret || reg > MAX_CHANNEL) {
> +				dev_err(&chip->client->dev,
> +					"reg must less or equal than %d\n",
> +					MAX_CHANNEL);
> +				return -EINVAL;
> +			}
> +
> +			ret = of_property_read_u32(child, "color", &color);
> +			if (ret) {
> +				dev_err(&chip->client->dev,
> +					"color must have value\n");
> +				return ret;
> +			}
> +
> +			if (color > 3 || !color) {
> +				dev_err(&chip->client->dev,
> +					"color must be Red, Green and Blue. The color is %d\n",
> +					color);
> +				return ret;
> +			}
> +			info[i].color_index = color;
> +			info[i].channel = reg;
> +			info[i].brightness = 0;
> +			i++;
> +		}
> +
> +		led->subled_info = info;
> +		led->num_colors = 3;
> +		cdev = &led->cdev;
> +		cdev->max_brightness = MAX_BRIGHTNESS;
> +		cdev->brightness_set_blocking = led_brightness_set;
> +		cdev->groups = led_sysfs_groups;
> +		init_data.fwnode = &np->fwnode;
> +
> +		ret = devm_led_classdev_register_ext(&chip->client->dev,
> +						     &led->cdev, &init_data);
> +
> +		if (ret) {
> +			dev_err(&chip->client->dev,
> +				"Unable register multicolor:%s\n", cdev->name);
> +			return ret;
> +		}
> +	} else {
> +		ret = of_property_read_u32(np, "reg", &reg);
> +		if (ret || reg > MAX_CHANNEL) {
> +			dev_err(&chip->client->dev,
> +				"reg must less or equal than %d\n",
> +				MAX_CHANNEL);
> +			return -EINVAL;
> +		}
> +		info = devm_kcalloc(&chip->client->dev, 1, sizeof(*info),
> +				    GFP_KERNEL);
> +		led->num_colors = 1;
> +		info[i].color_index = LED_COLOR_ID_WHITE;
> +		info[i].channel = reg;
> +		info[i].brightness = 0;
> +		led->subled_info = info;
> +		cdev = &led->cdev;
> +		cdev->max_brightness = MAX_BRIGHTNESS;
> +		cdev->brightness_set_blocking = led_brightness_set;
> +		cdev->groups = led_sysfs_groups;
> +		init_data.fwnode = &np->fwnode;
> +		ret = devm_led_classdev_register_ext(&chip->client->dev,
> +						     &led->cdev, &init_data);
> +		if (ret) {
> +			dev_err(&chip->client->dev, "Unable register led:%s\n",
> +				cdev->name);
> +			return ret;
> +		}
> +	}

Blank line

> +	return ret;
> +}
> +
> +static int mp3326_parse_dt(struct mp3326 *chip)
> +{
> +	struct device_node *np = dev_of_node(&chip->client->dev);
> +	struct device_node *child;
> +	int ret;
> +	int i = 0;
> +
> +	for_each_available_child_of_node(np, child) {
> +		ret = mp3326_add_led(chip, child, i);
> +		if (ret)
> +			return ret;
> +		i++;
> +	}
> +
> +	ret = regmap_write(chip->regmap, MP3326_PWM_CTRL_CHANNEL_9_16, 0);
> +	if (ret)
> +		return ret;

Blank line

> +	ret = regmap_write(chip->regmap, MP3326_PWM_CTRL_CHANNEL_1_8, 0);
> +	if (ret)
> +		return ret;

Blank line

> +	return 0;
> +}
> +
> +static int mp3326_leds_probe(struct i2c_client *client)
> +{
> +	struct mp3326 *chip;
> +	const struct reg_field *reg_fields;
> +	int count, i, j;
> +
> +	count = device_get_child_node_count(&client->dev);
> +	if (!count) {

Drop {

Please run scripts/checkpatch.pl and fix reported warnings. Then please
run `scripts/checkpatch.pl --strict` and (probably) fix more warnings.
Some warnings can be ignored, especially from --strict run, but the code
here looks like it needs a fix. Feel free to get in touch if the warning
is not clear.

> +		return dev_err_probe(&client->dev, -EINVAL,
> +				     "Incorrect number of leds (%d)", count);
> +	}

blank line

> +	chip = devm_kzalloc(&client->dev, struct_size(chip, leds, count),
> +			    GFP_KERNEL);
> +	if (!chip)
> +		return -ENOMEM;
> +
> +	chip->client = client;
> +	chip->num_of_leds = count;
> +	i2c_set_clientdata(client, chip);
> +	chip->regmap = devm_regmap_init_i2c(client, &MP3326_regmap_config);
> +	if (IS_ERR(chip->regmap))
> +		return PTR_ERR(chip->regmap);
> +
> +	for (i = 0; i < MAX_CHANNEL; i++) {
> +		reg_fields = channels_reg_fields[i];
> +		for (j = 0; j < MAX_CTRL; j++) {
> +			chip->regmap_fields[i][j] = devm_regmap_field_alloc(
> +				&client->dev, chip->regmap, reg_fields[j]);
> +			if (IS_ERR(chip->regmap_fields[i][j]))
> +				return PTR_ERR(chip->regmap_fields[i][j]);
> +		}
> +	}

Blank line

> +	if (mp3326_parse_dt(chip))
> +		return 1;

What is one? This looks like some sort of user-space or downstream
approach. That's not how it works for upstream kernel. Do not introduce
your downstream/user-space/other-system coding style and programming
interface.

You must use Linux approach.

There is no way probe function returns a "1". See other files as example.


> +	else
> +		return 0;
> +}
> +
> +static const struct i2c_device_id mp3326_id[] = { { "mp3326", 0 }, {} };

This must be formatted as kernel coding style. See other files as an
example.

> +MODULE_DEVICE_TABLE(i2c, mp3326_id);
> +
> +static const struct of_device_id mp3326_of_match[] = { { .compatible =
> +								 "mps,mp3326" },
> +						       {} };
> +MODULE_DEVICE_TABLE(of, mp3326_of_match);
> +
> +static struct i2c_driver mp3326_driver = {
> +	.probe = mp3326_leds_probe,
> +	.driver = {
> +			.name = "mp3326_led",
> +			.of_match_table = mp3326_of_match,
> +		   },
> +	.id_table = mp3326_id,
> +};
> +
> +module_i2c_driver(mp3326_driver);
> +MODULE_AUTHOR("Yuxi Wang <Yuxi.Wang@monolithicpower.com>");
> +MODULE_DESCRIPTION("MPS MP3326 LED driver");
> +MODULE_LICENSE("GPL");

Best regards,
Krzysztof