Re: [PATCH v5 3/3] iio: dac: Add AD5529R DAC driver support

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Channels not specified in the device tree are exposed to userspace but their hardware range is not explicitly configured.
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commit eb86f7024ceca6fa634016d239f7ccfbf35f6a11
Author: Janani Sunil <janani.sunil@analog.com>
Date:   Wed Jul 1 06:40:41 2026 +0000

iio: dac: Add AD5529R DAC driver support

This commit adds support for the Analog Devices AD5529R 16-channel, 12/16-bit
Digital to Analog Converter. The device communicates over SPI and supports
per-channel output range configuration.

> diff --git a/drivers/iio/dac/ad5529r.c b/drivers/iio/dac/ad5529r.c
> new file mode 100644
> --- /dev/null
> +++ b/drivers/iio/dac/ad5529r.c
[ ... ]
> +static int ad5529r_parse_channel_ranges(struct device *dev,
> +					struct ad5529r_state *st)
> +{
> +	s32 vals[2];
> +	int ret, range_idx;
> +	u32 ch;
> +
> +	device_for_each_child_node_scoped(dev, child) {
> +		ret = fwnode_property_read_u32(child, "reg", &ch);
> +		if (ret)
[ ... ]
> +		st->output_range_idx[ch] = range_idx;
> +		ret = regmap_write(st->regmap_16bit,
> +				   AD5529R_REG_OUT_RANGE(ch), range_idx);
> +		if (ret)
> +			return dev_err_probe(dev, ret,
> +					     "Failed to configure range for ch %u\n",
> +					     ch);
> +	}
> +
> +	return 0;
> +}
[ ... ]
> +static int ad5529r_probe(struct spi_device *spi)
> +{
[ ... ]
> +	ret = ad5529r_parse_channel_ranges(dev, st);
> +	if (ret)
> +		return ret;
> +
> +	indio_dev->name = st->model_data->model_name;
> +	indio_dev->info = &ad5529r_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = st->model_data->channels;
> +	indio_dev->num_channels = st->model_data->num_channels;

[Severity: High]
If a channel is omitted from the device tree during
ad5529r_parse_channel_ranges(), will it remain uninitialized in hardware
while still being unconditionally exposed to userspace here?

Since ad5529r_parse_channel_ranges() only configures the output range
registers for channels explicitly defined in the device tree child nodes,
unlisted channels will retain whatever state the hardware bootloader or reset
left them in.

The software state for these unlisted channels in st->output_range_idx
defaults to 0 (AD5529R_RANGE_0V_5V). Could this discrepancy cause unexpected
high-voltage outputs if userspace writes to these unconfigured hardware
channels?

> +
> +	return devm_iio_device_register(dev, indio_dev);
> +}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260701-ad5529r-driver-v5-0-ed087900e642@analog.com?part=3