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

[Jonathan Cameron <jic23@kernel.org>]

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;
>  	}