Hi! 2022-07-21 at 21:15, Paul Cercueil wrote: > When the IIO channel has a scale_available attribute, we want the values > contained to be properly converted the same way the scale value is. > > Since rescale_process_scale() may change the encoding type, we must > convert the IIO_AVAIL_LIST to a IIO_AVAIL_LIST_WITH_TYPE. > > Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx> > --- > drivers/iio/afe/iio-rescale.c | 85 +++++++++++++++++++++++++++++++++ > include/linux/iio/afe/rescale.h | 2 + > 2 files changed, 87 insertions(+) > > diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c > index 6949d2151025..5c9970b93384 100644 > --- a/drivers/iio/afe/iio-rescale.c > +++ b/drivers/iio/afe/iio-rescale.c > @@ -232,6 +232,18 @@ static int rescale_read_avail(struct iio_dev *indio_dev, > *type = IIO_VAL_INT; > return iio_read_avail_channel_raw(rescale->source, > vals, length); > + case IIO_CHAN_INFO_SCALE: > + if (rescale->chan_processed) { I think it is wrong to simply feed the info-scale to the source channel if it happens to be processed. It still needs the inverse rescale. But see below. > + return iio_read_avail_channel_attribute(rescale->source, > + vals, type, > + length, > + IIO_CHAN_INFO_SCALE); > + } else if (rescale->scale_len) { > + *length = rescale->scale_len; > + *vals = rescale->scale_data; > + return IIO_AVAIL_LIST_WITH_TYPE; > + } > + fallthrough; > default: > return -EINVAL; > } > @@ -266,11 +278,74 @@ static ssize_t rescale_write_ext_info(struct iio_dev *indio_dev, > buf, len); > } > > +static int rescale_init_scale_avail(struct device *dev, struct rescale *rescale) > +{ > + int ret, type, length, *data; > + const int *scale_raw; > + unsigned int i; > + size_t out_len; > + > + ret = iio_read_avail_channel_attribute(rescale->source, &scale_raw, > + &type, &length, > + IIO_CHAN_INFO_SCALE); > + if (ret < 0) > + return ret; > + > + switch (ret) { > + case IIO_AVAIL_LIST_WITH_TYPE: > + out_len = length; > + break; > + case IIO_AVAIL_LIST: > + if (type == IIO_VAL_INT) > + out_len = length * 3 / 1; > + else > + out_len = length * 3 / 2; > + break; > + default: > + /* TODO: Support IIO_AVAIL_RANGE */ > + return -EOPNOTSUPP; > + } > + > + data = devm_kzalloc(dev, sizeof(*data) * out_len, GFP_KERNEL); > + if (!data) > + return -ENOMEM; > + > + if (ret == IIO_AVAIL_LIST_WITH_TYPE) { > + memcpy(data, scale_raw, sizeof(*scale_raw) * length); > + } else if (type == IIO_VAL_INT) { > + for (i = 0; i < length; i++) { > + data[i * 3 + 0] = scale_raw[i]; > + data[i * 3 + 2] = IIO_VAL_INT; > + } > + } else { > + for (i = 0; i < length / 2; i++) { > + data[i * 3 + 0] = scale_raw[i * 2]; > + data[i * 3 + 1] = scale_raw[i * 2 + 1]; > + data[i * 3 + 2] = type; > + } > + } > + > + for (i = 0; i < out_len; i += 3) { > + ret = rescale_process_scale(rescale, data[i + 2], > + &data[i], &data[i + 1]); > + if (ret < 0) > + return ret; > + > + data[i + 2] = ret; > + } > + > + rescale->scale_len = out_len; > + rescale->scale_data = data; > + > + return 0; > +} > + > static int rescale_configure_channel(struct device *dev, > struct rescale *rescale) > { > struct iio_chan_spec *chan = &rescale->chan; > struct iio_chan_spec const *schan = rescale->source->channel; > + int ret; > > chan->indexed = 1; > chan->output = schan->output; > @@ -303,6 +378,16 @@ static int rescale_configure_channel(struct device *dev, > !rescale->chan_processed) > chan->info_mask_separate_available |= BIT(IIO_CHAN_INFO_RAW); > > + if (iio_channel_has_available(schan, IIO_CHAN_INFO_SCALE)) { > + chan->info_mask_separate_available |= BIT(IIO_CHAN_INFO_SCALE); > + > + if (!rescale->chan_processed) { > + ret = rescale_init_scale_avail(dev, rescale); > + if (ret) > + return ret; > + } > + } > + Does a (sane) processed channel really have a scale? That seems a bit fringe. Wouldn't it be better to conditionally publish availability of info-scale so that it isn't visible for processed channels and dodge that rabbit-hole? In either case, the above commented implementation of info-scale for rescaled processed channels is wrong (I think...). Cheers, Peter > return 0; > } > > diff --git a/include/linux/iio/afe/rescale.h b/include/linux/iio/afe/rescale.h > index 6eecb435488f..74de2962f864 100644 > --- a/include/linux/iio/afe/rescale.h > +++ b/include/linux/iio/afe/rescale.h > @@ -26,6 +26,8 @@ struct rescale { > s32 numerator; > s32 denominator; > s32 offset; > + int scale_len; > + int *scale_data; > }; > > int rescale_process_scale(struct rescale *rescale, int scale_type,