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

Andy Shevchenko
2025-03-19T12:11:47Z

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