Re: [PATCH v6 5/5] iio: dac: Add AD5529R DAC driver support

[Jonathan Cameron]

On Wed, 15 Jul 2026 13:41:08 +0200
Janani Sunil <janani.sunil@xxxxxxxxxx> wrote:

> Add support for AD5529R 16-channel, 12/16 bit Digital to Analog Converter
> from Analog Devices.
> 
> The device communicates over SPI and supports per-channel output range
> configuration. An optional external 4.096V reference can be used in
> place of the internal reference.
> 
> Signed-off-by: Janani Sunil <janani.sunil@xxxxxxxxxx>
Hi Janini

Fairly quick review as it is end of day here now.
A few things inline.

Thanks,

Jonathan


> diff --git a/drivers/iio/dac/ad5529r.c b/drivers/iio/dac/ad5529r.c
> new file mode 100644
> index 000000000000..c279dc530d68
> --- /dev/null
> +++ b/drivers/iio/dac/ad5529r.c

> +static int ad5529r_reset(struct ad5529r_state *st)
> +{
> +	struct reset_control *rst;
> +	int ret;
> +
> +	rst = devm_reset_control_get_optional_exclusive(&st->spi->dev, NULL);
> +	if (IS_ERR(rst))
> +		return PTR_ERR(rst);
> +
> +	if (rst) {
> +		ret = reset_control_assert(rst);
> +		if (ret)
> +			return ret;
> +
Nothing on the datasheet to say how long it needs to be asserted?

If it is very small maybe add a comment to say that here.
> +		ret = reset_control_deassert(rst);
> +		if (ret)
> +			return ret;

> +
> +static int ad5529r_probe(struct spi_device *spi)
> +{
> +	struct device *dev = &spi->dev;
> +	struct iio_dev *indio_dev;
> +	struct ad5529r_state *st;
> +	struct regmap_config regmap_8bit_cfg = ad5529r_regmap_8bit_config;
> +	struct regmap_config regmap_16bit_cfg = ad5529r_regmap_16bit_config;

I would fill both of these in using a designated initializer and do
it once we know the remaining fields.


	regmap_8bit_cfg = (struct regmap_config) {
		.name = "ad5529r-8bit",
		.reg_bits = 16,
		.val_bits = 8,
		.max_register = AD5529R_8BIT_REG_MAX,
		.read_flag_mask = AD5529R_SPI_READ_FLAG,
		.rd_table = &ad5529r_8bit_readable_table,
		.wr_table = &ad5529r_8bit_writeable_table,
		.reg_base = ...	
	};

That keeps everything in once place and removes the indirection of a template
that we then override parts of.


> +	bool external_vref;
> +	u32 dev_addr = 0;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	st = iio_priv(indio_dev);
> +
> +	st->spi = spi;
> +
> +	st->model_data = spi_get_device_match_data(spi);
> +	if (!st->model_data)
> +		return dev_err_probe(dev, -EINVAL,
> +				     "Failed to identify device variant\n");
> +
> +	device_property_read_u32(dev, "spi-device-addr", &dev_addr);
> +	if (dev_addr > 3)
> +		return dev_err_probe(dev, -EINVAL,
> +				     "spi-device-addr %u out of range [0, 3]\n",
> +				     dev_addr);
> +	regmap_8bit_cfg.reg_base = dev_addr << AD5529R_ADDR_SHIFT;
> +	regmap_16bit_cfg.reg_base = dev_addr << AD5529R_ADDR_SHIFT;
> +
> +	ret = devm_regulator_bulk_get_enable(dev, ARRAY_SIZE(ad5529r_supply_names),
> +					     ad5529r_supply_names);
> +	if (ret)
> +		return dev_err_probe(dev, ret,
> +				     "Failed to get and enable regulators\n");
> +
> +	ret = devm_regulator_get_enable_optional(dev, "hvss");
> +	if (ret && ret != -ENODEV)
> +		return dev_err_probe(dev, ret,
> +				     "Failed to get and enable hvss regulator\n");
> +
> +	ret = devm_regulator_get_enable_optional(dev, "vref");
> +	if (ret == -ENODEV)
> +		external_vref = false;
> +	else if (!ret)
> +		external_vref = true;
> +	else
> +		return dev_err_probe(dev, ret,
> +				     "Failed to get and enable vref regulator\n");

Slightly prefer these last two flipped so get the error of the way
a bit earlier.

> +