Re: [PATCH v5 10/11] input: misc: Add support for MAX7360 rotary

[Andy Shevchenko]

On Tue, Mar 18, 2025 at 05:26:26PM +0100, Mathieu Dubois-Briand wrote:
> Add driver for Maxim Integrated MAX7360 rotary encoder controller,
> supporting a single rotary switch.

...

> +	help
> +	  If you say yes here you get support for the rotary encoder on the
> +	  Maxim MAX7360 I/O Expander.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called max7360_rotary.

Seems all your patches have unaligned line widths in the help texts.

...

+ bitfield.h
+ device/devres.h
+ dev_printk.h

> +#include <linux/init.h>
> +#include <linux/input.h>
> +#include <linux/interrupt.h>
> +#include <linux/mfd/max7360.h>
> +#include <linux/property.h>

> +#include <linux/of.h>

Why?

> +#include <linux/platform_device.h>
> +#include <linux/pm_wakeirq.h>
> +#include <linux/regmap.h>

> +#include <linux/slab.h>

Not needed.

+ types.h

...

> +static irqreturn_t max7360_rotary_irq(int irq, void *data)
> +{
> +	struct max7360_rotary *max7360_rotary = data;
> +	int val;
> +	int ret;
> +
> +	ret = regmap_read(max7360_rotary->regmap, MAX7360_REG_RTR_CNT, &val);
> +	if (ret < 0) {
> +		dev_err(&max7360_rotary->input->dev,
> +			"Failed to read rotary counter\n");
> +		return IRQ_NONE;
> +	}
> +
> +	if (val == 0) {
> +		dev_dbg(&max7360_rotary->input->dev,
> +			"Got a spurious interrupt\n");
> +
> +		return IRQ_NONE;
> +	}
> +
> +	input_report_rel(max7360_rotary->input, max7360_rotary->axis,
> +			 (int8_t)val);

This is strange:
1) why casting to begin with?
2) why to C type and not kernel (s8) type?

> +	input_sync(max7360_rotary->input);
> +
> +	return IRQ_HANDLED;
> +}

...

> +static int max7360_rotary_hw_init(struct max7360_rotary *max7360_rotary)
> +{
> +	int val;
> +	int ret;
> +
> +	val = FIELD_PREP(MAX7360_ROT_DEBOUNCE, max7360_rotary->debounce_ms) |
> +		FIELD_PREP(MAX7360_ROT_INTCNT, 1) | MAX7360_ROT_INTCNT_DLY;
> +	ret = regmap_write(max7360_rotary->regmap, MAX7360_REG_RTRCFG, val);
> +	if (ret) {
> +		dev_err(&max7360_rotary->input->dev,
> +			"Failed to set max7360 rotary encoder configuration\n");

> +		return ret;
> +	}
> +
> +	return 0;

Just

	return ret;

?

> +}

...

> +static int max7360_rotary_probe(struct platform_device *pdev)
> +{
> +	struct max7360_rotary *max7360_rotary;

	struct device *dev = &pdev->dev;

> +	struct input_dev *input;
> +	int irq;
> +	int ret;

> +	if (!pdev->dev.parent)
> +		return dev_err_probe(&pdev->dev, -ENODEV, "No parent device\n");

Just check for regmap.

> +	irq = platform_get_irq_byname(to_platform_device(pdev->dev.parent),
> +				      "inti");

One line (and instead of that dance with container_of(), just use
fwnode_irq_get_byname().

> +	if (irq < 0)
> +		return irq;
> +
> +	max7360_rotary = devm_kzalloc(&pdev->dev, sizeof(*max7360_rotary),
> +				      GFP_KERNEL);

One line.

> +	if (!max7360_rotary)
> +		return -ENOMEM;
> +
> +	max7360_rotary->regmap = dev_get_regmap(pdev->dev.parent, NULL);
> +	if (!max7360_rotary->regmap)

> +		dev_err_probe(&pdev->dev, -ENODEV,
> +			      "Could not get parent regmap\n");

One line.

> +	device_property_read_u32(pdev->dev.parent, "linux,axis",
> +				 &max7360_rotary->axis);
> +	device_property_read_u32(pdev->dev.parent, "rotary-debounce-delay-ms",
> +				 &max7360_rotary->debounce_ms);

No, instead of parent, make sure that fwnode is propagated to the children (and
tadaam, it's done in MFD already).

> +	if (max7360_rotary->debounce_ms > MAX7360_ROT_DEBOUNCE_MAX)
> +		return dev_err_probe(&pdev->dev, -EINVAL,
> +				     "Invalid debounce timing: %u\n",
> +				     max7360_rotary->debounce_ms);
> +
> +	input = devm_input_allocate_device(&pdev->dev);
> +	if (!input)
> +		return -ENOMEM;
> +
> +	max7360_rotary->input = input;
> +
> +	input->id.bustype = BUS_I2C;
> +	input->name = pdev->name;
> +	input->dev.parent = &pdev->dev;
> +
> +	input_set_capability(input, EV_REL, max7360_rotary->axis);
> +	input_set_drvdata(input, max7360_rotary);
> +
> +	ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
> +					max7360_rotary_irq,

> +					IRQF_TRIGGER_LOW | IRQF_ONESHOT | IRQF_SHARED,

What's wrong with the firmware description of the interrupt?

> +					"max7360-rotary", max7360_rotary);
> +	if (ret)
> +		return dev_err_probe(&pdev->dev, ret,
> +				     "Failed to register interrupt\n");
> +
> +	ret = input_register_device(input);
> +	if (ret)

> +		return dev_err_probe(&pdev->dev, ret,
> +				     "Could not register input device\n");

One line.

> +	platform_set_drvdata(pdev, max7360_rotary);

Is it used?

> +	device_init_wakeup(&pdev->dev, true);
> +	ret = dev_pm_set_wake_irq(&pdev->dev, irq);
> +	if (ret)
> +		dev_warn(&pdev->dev, "Failed to set up wakeup irq: %d\n", ret);
> +
> +	ret = max7360_rotary_hw_init(max7360_rotary);
> +	if (ret)
> +		return dev_err_probe(&pdev->dev, ret,
> +				     "Failed to initialize max7360 rotary\n");

In the other driver the HW initialisation and wake setup were swapped,
can you choose one way? Otherwise both cases need a comment to explain
the order of calls.

> +	return 0;
> +}

-- 
With Best Regards,
Andy Shevchenko