RE: [PATCH v2 07/10] iio: core: Introduce IIO_CHAN_INFO_FILTER_OUTLIERS_THRESH and _PERIOD

From: Tirdea, Irina
Date: Tue Jan 27 2015 - 11:21:11 EST



> -----Original Message-----
> From: Jonathan Cameron [mailto:jic23@xxxxxxxxxx]
> Sent: 26 January, 2015 21:02
> To: Baluta, Daniel
> Cc: Tirdea, Irina; linux-iio@xxxxxxxxxxxxxxx; Linux Kernel Mailing List; Dogaru, Vlad; Hartmut Knaack; Lars-Peter Clausen; Peter
> Meerwald
> Subject: Re: [PATCH v2 07/10] iio: core: Introduce IIO_CHAN_INFO_FILTER_OUTLIERS_THRESH and _PERIOD
>
> On 26/01/15 14:40, Daniel Baluta wrote:
> > On Mon, Jan 26, 2015 at 1:07 AM, Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
> >> On 11/01/15 19:10, Irina Tirdea wrote:
> >>> The pedometer needs to filter out false steps that might be generated by
> >>> tapping the foot, sitting, etc. To do that it computes the number of
> >>> steps that occur in a given time and decides the user is moving only
> >>> if this value is over a threshold. E.g.: the user starts moving only
> >>> if he takes 4 steps in 3 seconds. This filter is applied only when
> >>> the user starts moving.
> >>>
> >>> A device that has such pedometer functionality is Freescale's MMA9553L:
> >>> http://www.freescale.com/files/sensors/doc/ref_manual/MMA9553LSWRM.pdf.
> >>>
> >>> To export this feature, this patch introduces
> >>> IIO_CHAN_INFO_FILTER_OUTLIERS_THRESH and IIO_CHAN_INFO_FILTER_OUTLIERS_PERIOD.
> >>> For the pedometer, in_steps_filter_outlier_thresh will specify the number of
> >>> steps that need to occur in in_steps_filter_outlier_period seconds so that
> >>> the pedometer decides the user is moving.
> >>>
> >>> Signed-off-by: Irina Tirdea <irina.tirdea@xxxxxxxxx>
> >> I wonder if the naming here is infact too generic. They aren't what
> >> people would normally think of as outliers. That would be removing
> >> missidentified steps mid way through grabbing data (to my mind).
> >>
> >> These are almost a 'debounce' of the transition from stationary to
> >> walking... Maybe there is another better term. All suggestions welcome!
> >
> > What about:
> >
> > in_steps_debounce_count instead of in_steps_filter_outlier_thresh
> > and
> > in_steps_debounce_delay instead of in_steps_filter_outlier_period.
> >
> > Also in_steps_debounce_time could work for in_steps_filter_outlier_period.
> Hmm. Slight preference for debounce_time.
>
> I can't come up with a better option, but we'd best see if anyone else has
> a better idea for a day or two!

I also agree with in_steps_debounce_count and in_steps_debounce_time, but I'll wait a couple of days before sending v3 maybe someone comes up with something better.
Thanks Daniel and Jonathan!

> >
> >>
> >>> ---
> >>> Documentation/ABI/testing/sysfs-bus-iio | 21 +++++++++++++++++++++
> >>> drivers/iio/industrialio-core.c | 2 ++
> >>> include/linux/iio/iio.h | 2 ++
> >>> 3 files changed, 25 insertions(+)
> >>>
> >>> diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
> >>> index c03a140..e009f49 100644
> >>> --- a/Documentation/ABI/testing/sysfs-bus-iio
> >>> +++ b/Documentation/ABI/testing/sysfs-bus-iio
> >>> @@ -1193,3 +1193,24 @@ Description:
> >>> This attribute is used to read the current speed value of the
> >>> user (which is the norm or magnitude of the velocity vector).
> >>> Units after application of scale are m/s.
> >>> +
> >>> +What: /sys/.../iio:deviceX/in_steps_filter_outliers_period
> >>> +KernelVersion: 3.20
> >>> +Contact: linux-iio@xxxxxxxxxxxxxxx
> >>> +Description:
> >>> + Specifies the number of seconds in which we compute the
> >>> + values so we can decide if they are outlier values and
> >>> + need to be filter out. These computed values are then
> >>> + compared with in_steps_filter_outliers_thresh. E.g. for steps:
> >>> + specifies number of seconds in which we compute the steps
> >>> + that occur in order to decide if the consumer is making steps.
> >>> +
> >>> +What: /sys/.../iio:deviceX/in_steps_filter_outliers_thresh
> >>> +KernelVersion: 3.20
> >>> +Contact: linux-iio@xxxxxxxxxxxxxxx
> >>> +Description:
> >>> + Specifies a threshold for filtering outlier values: if value
> >>> + measured in in_steps_filter_outliers_period seconds is below
> >>> + threshold, we filter it out. E.g. for steps: specifies number
> >>> + of steps that must occur within in_steps_filter_outliers_period
> >>> + for the pedometer to decide the consumer is making steps.
> >>> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> >>> index 4ee6fdf..81678b3 100644
> >>> --- a/drivers/iio/industrialio-core.c
> >>> +++ b/drivers/iio/industrialio-core.c
> >>> @@ -126,6 +126,8 @@ static const char * const iio_chan_info_postfix[] = {
> >>> [IIO_CHAN_INFO_ENABLE] = "en",
> >>> [IIO_CHAN_INFO_CALIBHEIGHT] = "calibheight",
> >>> [IIO_CHAN_INFO_CALIBWEIGHT] = "calibweight",
> >>> + [IIO_CHAN_INFO_FILTER_OUTLIERS_THRESH] = "filter_outliers_thresh",
> >>> + [IIO_CHAN_INFO_FILTER_OUTLIERS_PERIOD] = "filter_outliers_period",
> >>> };
> >>>
> >>> /**
> >>> diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
> >>> index 752a929..b6b12ac 100644
> >>> --- a/include/linux/iio/iio.h
> >>> +++ b/include/linux/iio/iio.h
> >>> @@ -41,6 +41,8 @@ enum iio_chan_info_enum {
> >>> IIO_CHAN_INFO_ENABLE,
> >>> IIO_CHAN_INFO_CALIBHEIGHT,
> >>> IIO_CHAN_INFO_CALIBWEIGHT,
> >>> + IIO_CHAN_INFO_FILTER_OUTLIERS_THRESH,
> >>> + IIO_CHAN_INFO_FILTER_OUTLIERS_PERIOD,
> >>> };
> >>>
> >>> enum iio_shared_by {
> >>>
> >>
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