Re: [PATCH v2 7/7] iio: bu27034: Add a read only HWARDWAREGAIN

Jonathan Cameron
2024-07-07T13:14:16Z

On Fri, 5 Jul 2024 13:55:49 +0300
Matti Vaittinen <mazziesaccount@gmail.com> wrote:

Typo in patch title. If nothing much else comes up I can fix whilst applying.

> The ROHM BU27034 light sensor has two data channels for measuring
> different frequencies of light. The result from these channels is
> combined into Lux value while the raw channel values are reported via
> intensity channels.
>
> Both of the intensity channels have adjustable gain setting which
> impacts the scale of the raw channels. Eg, doubling the gain will double
> the values read from the raw channels, which halves the scale value. The
> integration time can also be set for the sensor. This does also have an
> impact to the scale of the intensity channels because increasing the
> integration time will also increase the values reported via the raw
> channels.
>
> Impact of integration time to the scale and the fact that the scale value
> does not start from '1', can make it hard for a human reader to compute the
> gain values based on the scale.
>
> Add read-only HARDWAREGAIN to help debugging.
>
> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>

Rest of this series looks good to me and I'm fine making appropriate tweaks
for stuff I identified whilst applying.

Will give a bit of time for DT maintainers to look at the renames and check
we haven't missed anything subtle there.

Jonathan

>
> ---
> Revision history:
> v1 => v2:
> - fix switch case fallthrough warning by adding explicit return
> ---
> drivers/iio/light/rohm-bu27034.c | 15 ++++++++++++++-
> 1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iio/light/rohm-bu27034.c b/drivers/iio/light/rohm-bu27034.c
> index ec4f9bef83f8..76711c3cdf7c 100644
> --- a/drivers/iio/light/rohm-bu27034.c
> +++ b/drivers/iio/light/rohm-bu27034.c
> @@ -148,7 +148,8 @@ static const struct iio_itime_sel_mul bu27034_itimes[] = {
> .type = IIO_INTENSITY, \
> .channel = BU27034_CHAN_##_name, \
> .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
> - BIT(IIO_CHAN_INFO_SCALE), \
> + BIT(IIO_CHAN_INFO_SCALE) | \
> + BIT(IIO_CHAN_INFO_HARDWAREGAIN), \
> .info_mask_separate_available = BIT(IIO_CHAN_INFO_SCALE), \
> .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_INT_TIME), \
> .info_mask_shared_by_all_available = \
> @@ -989,6 +990,13 @@ static int bu27034_read_raw(struct iio_dev *idev,
>
> return IIO_VAL_INT_PLUS_MICRO;
>
> + case IIO_CHAN_INFO_HARDWAREGAIN:
> + ret = bu27034_get_gain(data, chan->channel, val);
> + if (ret)
> + return ret;
> +
> + return IIO_VAL_INT;
> +
> case IIO_CHAN_INFO_SCALE:
> return bu27034_get_scale(data, chan->channel, val, val2);
>
> @@ -1033,12 +1041,17 @@ static int bu27034_write_raw_get_fmt(struct iio_dev *indio_dev,
> struct iio_chan_spec const *chan,
> long mask)
> {
> + struct bu27034_data *data = iio_priv(indio_dev);
>
> switch (mask) {
> case IIO_CHAN_INFO_SCALE:
> return IIO_VAL_INT_PLUS_NANO;
> case IIO_CHAN_INFO_INT_TIME:
> return IIO_VAL_INT_PLUS_MICRO;
> + case IIO_CHAN_INFO_HARDWAREGAIN:
> + dev_dbg(data->dev,
> + "HARDWAREGAIN is read-only, use scale to set\n");
> + return -EINVAL;
> default:
> return -EINVAL;
> }