Messages in this thread | | | From | David Lechner <> | Date | Sat, 30 Sep 2023 16:23:19 -0500 | Subject | Re: [PATCH v3 14/27] staging: iio: resolver: ad2s1210: implement hysteresis as channel attr |
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On Sat, Sep 30, 2023 at 10:00 AM Jonathan Cameron <jic23@kernel.org> wrote: > > On Fri, 29 Sep 2023 12:53:00 -0500 > David Lechner <dlechner@baylibre.com> wrote: > > > On Fri, Sep 29, 2023 at 12:25 PM David Lechner <dlechner@baylibre.com> wrote: > > > > > > The AD2S1210 resolver has a hysteresis feature that can be used to > > > prevent flicker in the LSB of the position register. This can be either > > > enabled or disabled. Disabling hysteresis is useful for increasing > > > precision by oversampling. > > > > > > Signed-off-by: David Lechner <dlechner@baylibre.com> > > > --- > > > > ... > > > > > +static int ad2s1210_read_avail(struct iio_dev *indio_dev, > > > + struct iio_chan_spec const *chan, > > > + const int **vals, int *type, > > > + int *length, long mask) > > > +{ > > > + static const int hysteresis_available[] = { 0, 1 }; > > > > This is basically an enable/disable. Should the 1 value be changed to the > > appropriate radians value since this is hysteresis on the position > > (angle) channel? > > Good point. However it should be in the _raw units. The text is > slightly more explicit on this for > the variant of hysteresis applied to threshold events as it's > added or substracted from a threshold (and thresholds are in > _raw readings unless only _processed is available). > > Does that make 0, 1 correct as we are talking about LSB only? >
It is currently only correct (as a raw value) if the selected resolution is 16-bit. So I will need to fix this so the value is `1 << (16 - resolution)`.
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