Re: [PATCH v10 6/6] iio: magnetometer: Add mmc5633 sensor

[Andy Shevchenko <andriy.shevchenko@intel.com>]

On Tue, Nov 04, 2025 at 10:46:44AM -0500, Frank Li wrote:
> Add mmc5633 sensor basic support.
> - Support read 20 bits X/Y/Z magnetic.
> - Support I3C HDR mode to send start measurememt command.
> - Support I3C HDR mode to read all sensors data by one command.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
with some nit-picks below.

...

> +static int mmc5633_take_measurement(struct mmc5633_data *data, int address)
> +{
> +	unsigned int reg_status;
> +	int ret;

> +	int val;

regmap API uses unsigned int for value field.

> +	val = (address == MMC5633_TEMPERATURE) ? MMC5633_CTRL0_MEAS_T : MMC5633_CTRL0_MEAS_M;
> +	ret = regmap_write(data->regmap, MMC5633_REG_CTRL0, val);
> +	if (ret < 0)
> +		return ret;
> +
> +	val = (address == MMC5633_TEMPERATURE) ?
> +	      MMC5633_STATUS1_MEAS_T_DONE_BIT : MMC5633_STATUS1_MEAS_M_DONE_BIT;
> +	ret = regmap_read_poll_timeout(data->regmap, MMC5633_REG_STATUS1, reg_status,
> +				       reg_status & val,
> +				       10 * USEC_PER_MSEC,
> +				       100 * 10 * USEC_PER_MSEC);
> +	if (ret) {
> +		dev_err(regmap_get_device(data->regmap), "data not ready\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}

...

> +static int mmc5633_read_measurement(struct mmc5633_data *data, int address, void *buf, size_t sz)
> +{
> +	struct device *dev = regmap_get_device(data->regmap);
> +	u8 data_cmd[2], status[2];
> +	int ret, val, ready;

Ditto.

> +	if (mmc5633_is_support_hdr(data)) {
> +		struct i3c_xfer xfers_wr_cmd[] = {
> +			{
> +				.cmd = 0x3b,
> +				.len = 2,
> +				.data.out = data_cmd,
> +			}
> +		};
> +		struct i3c_xfer xfers_rd_sta_cmd[] = {
> +			{
> +				.cmd = 0x23 | BIT(7), /* RDSTA CMD */
> +				.len = 2,
> +				.data.in = status,
> +			},
> +		};
> +		struct i3c_xfer xfers_rd_data_cmd[] = {
> +			{
> +				.cmd = 0x22 | BIT(7), /* RDLONG CMD */
> +				.len = sz,
> +				.data.in = buf,
> +			},
> +		};

Still do not see a justification for an array to use, but as I said I leave it
to Jonathan to decide.

> +		data_cmd[0] = 0;
> +		data_cmd[1] = (address == MMC5633_TEMPERATURE) ?
> +			      MMC5633_HDR_CTRL0_MEAS_T : MMC5633_HDR_CTRL0_MEAS_M;
> +
> +		ret = i3c_device_do_xfers(data->i3cdev, xfers_wr_cmd,
> +					  ARRAY_SIZE(xfers_wr_cmd), I3C_HDR_DDR);
> +		if (ret < 0)
> +			return ret;
> +
> +		ready = (address == MMC5633_TEMPERATURE) ?
> +			MMC5633_STATUS1_MEAS_T_DONE_BIT : MMC5633_STATUS1_MEAS_M_DONE_BIT;
> +		ret = read_poll_timeout(i3c_device_do_xfers, val,

> +					val ||
> +					status[0] & ready,

One line and probably you want to add parentheses for better understanding, not
everybody remembers the operator precedence by heart.

> +					10 * USEC_PER_MSEC,
> +					100 * 10 * USEC_PER_MSEC, 0,
> +					data->i3cdev, xfers_rd_sta_cmd,
> +					ARRAY_SIZE(xfers_rd_sta_cmd), I3C_HDR_DDR);
> +		if (ret) {
> +			dev_err(dev, "data not ready\n");
> +			return ret;
> +		}
> +		if (val) {
> +			dev_err(dev, "i3c transfer error\n");
> +			return val;
> +		}
> +		return i3c_device_do_xfers(data->i3cdev, xfers_rd_data_cmd,
> +					   ARRAY_SIZE(xfers_rd_data_cmd), I3C_HDR_DDR);
> +	}
> +
> +	/* Fallback to use SDR/I2C mode */
> +	ret = mmc5633_take_measurement(data, address);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (address == MMC5633_TEMPERATURE)
> +		/*
> +		 * Put tempeature to last byte of buff to align HDR case.
> +		 * I3C will early terminate data read if previous data is not
> +		 * available.
> +		 */
> +		return regmap_bulk_read(data->regmap, MMC5633_REG_TOUT, buf + sz - 1, 1);
> +
> +	return regmap_bulk_read(data->regmap, MMC5633_REG_XOUT0, buf, sz);
> +}

...

> +static int mmc5633_read_avail(struct iio_dev *indio_dev,
> +			      struct iio_chan_spec const *chan,
> +			      const int **vals,
> +			      int *type,
> +			      int *length,
> +			      long mask)

Other functions use different style, I believe it can occupy less LoCs.

...

> +static int mmc5633_i3c_probe(struct i3c_device *i3cdev)
> +{
> +	struct device *dev = i3cdev_to_dev(i3cdev);
> +	struct regmap *regmap;
> +	char *name;

> +	name = devm_kasprintf(dev, GFP_KERNEL, "mmc5633(%s)", dev_name(dev));

I agree on idea behind this, but I think () can be problematic for some shell
scripts, I would go with the simple mmc5633_%s or similar.

> +	if (!name)
> +		return -ENOMEM;
> +
> +	regmap = devm_regmap_init_i3c(i3cdev, &mmc5633_regmap_config);
> +	if (IS_ERR(regmap))
> +		return dev_err_probe(dev, PTR_ERR(regmap),
> +				     "Failed to register i3c regmap\n");
> +
> +	return mmc5633_common_probe(regmap, name, i3cdev);
> +}

-- 
With Best Regards,
Andy Shevchenko