Re: [PATCH v3 2/2] iio: light: veml3328: add support for new device

[Jonathan Cameron <jic23@kernel.org>]

On Sat, 30 May 2026 19:06:47 +0200
Joshua Crofts <joshua.crofts1@gmail.com> wrote:

> Add support for the Vishay VEML3328 RGB/IR light sensor communicating
> via I2C (SMBus compatible).
> 
> Also add a new entry for said driver into Kconfig and Makefile.
> 
> Assisted-by: Gemini:3.1-Pro
> Signed-off-by: Joshua Crofts <joshua.crofts1@gmail.com>
Hi Joshua,

I didn't find anything extras so this is just some more explanation for
the Sashiko comments.

Give we are approaching the end of the cycle, feel free to do a new version
quicker than normal if you are sure on what needs changing.

Jonathan

> diff --git a/drivers/iio/light/veml3328.c b/drivers/iio/light/veml3328.c
> new file mode 100644
> index 000000000000..1def67fd9b51
> --- /dev/null
> +++ b/drivers/iio/light/veml3328.c

> +static int veml3328_read_raw(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan,
> +			     int *val, int *val2, long mask)
> +{
> +	struct veml3328_data *data = iio_priv(indio_dev);
> +	struct regmap *regmap = data->regmap;
> +	struct device *dev = regmap_get_device(regmap);
> +	unsigned int reg_val;
> +	int it_inx, gain_inx;
> +	int ret;
> +
> +	PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(dev, pm);
> +	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
> +	if (ret)
> +		return ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		ret = regmap_read(regmap, chan->address, &reg_val);
> +		if (ret)
> +			return ret;
> +
> +		*val = reg_val;
> +		return IIO_VAL_INT;
> +
> +	case IIO_CHAN_INFO_INT_TIME:
> +		ret = regmap_read(regmap, VEML3328_REG_CONF, &reg_val);
> +		if (ret)
> +			return ret;
> +
> +		it_inx = FIELD_GET(VEML3328_CONF_IT_MASK, reg_val);
> +		if (it_inx >= ARRAY_SIZE(veml3328_it_times))
> +			return -EINVAL;
> +
> +		*val = veml3328_it_times[it_inx][0];
> +		*val2 = veml3328_it_times[it_inx][1];
> +		return IIO_VAL_INT_PLUS_MICRO;
> +
> +	case IIO_CHAN_INFO_SCALE:
> +		ret = regmap_read(regmap, VEML3328_REG_CONF, &reg_val);
> +		if (ret)
> +			return ret;
> +
> +		it_inx = FIELD_GET(VEML3328_CONF_IT_MASK, reg_val);
> +		gain_inx = FIELD_GET(VEML3328_CONF_GAIN_MASK, reg_val);
> +
> +		if (it_inx >= ARRAY_SIZE(veml3328_it_times) || gain_inx >= 4)
> +			return -EINVAL;
> +
> +		/* Stride by 2 through the flattened array to match (val, val2) */
> +		*val = veml3328_scale_vals[it_inx][gain_inx * 2];
> +		*val2 = veml3328_scale_vals[it_inx][gain_inx * 2 + 1];
> +
> +		return IIO_VAL_INT_PLUS_MICRO;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int veml3328_read_avail(struct iio_dev *indio_dev,
> +			       struct iio_chan_spec const *chan,
> +			       const int **vals, int *type, int *length,
> +			       long mask)
> +{
> +	struct veml3328_data *data = iio_priv(indio_dev);
> +	struct regmap *regmap = data->regmap;
> +	struct device *dev = regmap_get_device(data->regmap);
> +	unsigned int reg_val;
> +	int ret, it_inx;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_INT_TIME:
> +		*length = ARRAY_SIZE(veml3328_it_times) * 2;
> +		*vals = (const int *)veml3328_it_times;
> +		*type = IIO_VAL_INT_PLUS_MICRO;
> +		return IIO_AVAIL_LIST;
> +
> +	case IIO_CHAN_INFO_SCALE:

Under the hood, like all the cleanup.h magic, this instantiates a local
variable - the cleanup scope is tided to that and scope for switch statements
is a funny thing - it's not per case, but rather the whole switch.
Hence need to add {} to define the scope for this case block.

Otherwise you enter this switch via another path and the local variable
is unassigned, but the __free() that cleans it up is set. Hence you get
a use of undefined variable.

> +		PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(dev, pm);
> +		ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
> +		if (ret)
> +			return ret;
> +
> +		ret = regmap_read(regmap, VEML3328_REG_CONF, &reg_val);
> +		if (ret)
> +			return ret;
> +
> +		it_inx = FIELD_GET(VEML3328_CONF_IT_MASK, reg_val);
> +		if (it_inx >= ARRAY_SIZE(veml3328_it_times))
> +			return -EINVAL;
> +
> +		*length = 8;
> +		*vals = (const int *)veml3328_scale_vals[it_inx];
> +		*type = IIO_VAL_INT_PLUS_MICRO;
> +		return IIO_AVAIL_LIST;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int veml3328_write_raw(struct iio_dev *indio_dev,
> +			      struct iio_chan_spec const *chan,
> +			      int val, int val2, long mask)
> +{
> +	struct veml3328_data *data = iio_priv(indio_dev);
> +	struct regmap *regmap = data->regmap;
> +	struct device *dev = regmap_get_device(regmap);
> +	unsigned int reg_val;
> +	int i, it_inx;
> +	int ret;
> +
> +	PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(dev, pm);
> +	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
> +	if (ret)
> +		return ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_INT_TIME:
> +		if (val != 0)
> +			return -EINVAL;
> +
> +		for (i = 0; i < ARRAY_SIZE(veml3328_it_times); i++) {
> +			if (veml3328_it_times[i][1] == val2)
> +				break;
> +		}
> +
> +		if (i == ARRAY_SIZE(veml3328_it_times))
> +			return -EINVAL;
> +
> +		return regmap_update_bits(regmap, VEML3328_REG_CONF,
> +					  VEML3328_CONF_IT_MASK,
> +					  FIELD_PREP(VEML3328_CONF_IT_MASK, i));
> +
> +	case IIO_CHAN_INFO_SCALE:
> +		ret = regmap_read(regmap, VEML3328_REG_CONF, &reg_val);

Hmm. The comment made by sashiko on this is also possibly correct.
The write to INT_TIME can race with the write to INFO_SCALE.  Whilst that's
not a normal use model (one thread would typically set up all the parameters)
you could end up with picking a scale based on an int time that isn't the current
one. I'd just throw a guard(mutex)(&data->lock) above this whole switch so we don't have
to think about it. (and a mutex in data, plus initialization etc).


> +		if (ret)
> +			return ret;
> +
> +		it_inx = FIELD_GET(VEML3328_CONF_IT_MASK, reg_val);
> +		if (it_inx >= ARRAY_SIZE(veml3328_it_times))
> +			return -EINVAL;
> +
> +		for (i = 0; i < 4; i++) {
> +			if (val == veml3328_scale_vals[it_inx][i * 2] &&
> +			    val2 == veml3328_scale_vals[it_inx][i * 2 + 1])
> +				break;
> +		}
> +
> +		if (i == 4)
> +			return -EINVAL;
> +
> +		return regmap_update_bits(regmap, VEML3328_REG_CONF,
> +					  VEML3328_CONF_GAIN_MASK,
> +					  FIELD_PREP(VEML3328_CONF_GAIN_MASK, i));
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct iio_info veml3328_info = {
> +	.read_raw = veml3328_read_raw,
> +	.write_raw = veml3328_write_raw,
> +	.read_avail = veml3328_read_avail,
> +};
> +
> +static int veml3328_probe(struct i2c_client *client)
> +{

> +
> +	pm_runtime_set_active(dev);
> +	pm_runtime_set_autosuspend_delay(dev, 2000);
> +	pm_runtime_use_autosuspend(dev);

As per other thread check this results in power down.
If it doesn't, try moving autosupend calls after devm_pm_runtime_enable()
and see if that is enough.  Otherwise, you can either manipulate the counters
or I think just call pm_runtime_idle() to force it off immediately.


> +
> +	ret = devm_pm_runtime_enable(dev);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Failed to enable runtime PM\n");
> +
> +	return devm_iio_device_register(dev, indio_dev);
> +}