On Fri, 13 Aug 2021 11:46:24 +0800
hui.liu <hui.liu@xxxxxxxxxxxx> wrote:
> On Thu, 2021-08-12 at 19:07 +0100, Jonathan Cameron wrote:
> > On Thu, 12 Aug 2021 13:48:43 +0800
> > Hui Liu <hui.liu@xxxxxxxxxxxx> wrote:
> >
> > > Add support IIO_CHAN_INFO_RAW case.
> >
> > Why?
> >
> > We almost never support both RAW and PROCESSED as userspace should be
> > fine to use either. There are a few reasons we've let drivers do
> > this but I would like know why it matters to you and it definitely
> > needs to be in the patch description.
> >
> Hi Jonathan,
>
> 1. To support ADC consumers' different types of requirement: some
> consumers want to call iio_read_channel_raw to get raw data, the others
> use iio_read_channel_processed to get voltage.
Give an example of the consumer using the raw channel readback (without
acess to any scaling information?)
> 2. In our origin driver, if consumer call iio_read_channel_processed,
> read back value is raw data.
>
> Could we use SCALE instead of PROCESSED in patch for next version, or
> what's your suggestion?
That would unfortunately be a userspace ABI change. We can add interfaces
but taking them away is normally a problem :(
Your reasons here are fine, subject to information on what consumer cares
about having _RAW, please resend the patch with this information added
to the description.
Thanks,
Jonathan
>
> Thanks.
>
> > >
> > > Signed-off-by: Hui Liu <hui.liu@xxxxxxxxxxxx>
> > > ---
> > > drivers/iio/adc/mt6577_auxadc.c | 16 +++++++++++++++-
> > > 1 file changed, 15 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/iio/adc/mt6577_auxadc.c
> > > b/drivers/iio/adc/mt6577_auxadc.c
> > > index 79c1dd68b909..e995d43287b2 100644
> > > --- a/drivers/iio/adc/mt6577_auxadc.c
> > > +++ b/drivers/iio/adc/mt6577_auxadc.c
> > > @@ -60,7 +60,8 @@ static const struct mtk_auxadc_compatible
> > > mt6765_compat = {
> > > .type = IIO_VOLTAGE,
> > > \
> > > .indexed = 1,
> > > \
> > > .channel = (idx), \
> > > - .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), \
> > > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> > > \
> > > + BIT(IIO_CHAN_INFO_PROCESSED), \
> > > }
> > >
> > > static const struct iio_chan_spec mt6577_auxadc_iio_channels[] = {
> > > @@ -181,6 +182,19 @@ static int mt6577_auxadc_read_raw(struct
> > > iio_dev *indio_dev,
> > > struct mt6577_auxadc_device *adc_dev = iio_priv(indio_dev);
> > >
> > > switch (info) {
> > > + case IIO_CHAN_INFO_RAW:
> > > + *val = mt6577_auxadc_read(indio_dev, chan);
> > > + if (*val < 0) {
> > > + dev_notice(indio_dev->dev.parent,
> > > + "failed to sample data on
> > > channel[%d]\n",
> > > + chan->channel);
> > > + return *val;
> > > + }
> > > + if (adc_dev->dev_comp->sample_data_cali)
> > > + *val = mt_auxadc_get_cali_data(*val, true);
> > > +
> > > + return IIO_VAL_INT;
> > > +
> > > case IIO_CHAN_INFO_PROCESSED:
> > > *val = mt6577_auxadc_read(indio_dev, chan);
> > > if (*val < 0) {
> >
> >
