Re: [RFC PATCH 3/8] iio: core: Introduce new MOTION event

[Daniel Baluta <daniel.baluta@intel.com>]

On Sat, Oct 4, 2014 at 4:12 PM, Jonathan Cameron <jic23@kernel.org> wrote:
> On 02/10/14 14:43, Daniel Baluta wrote:
>> This is to be used by drivers to signal detection of motion. We also
>> add some possible values for motion as IIO events modifiers:
>>       * running
>>       * jogging
>>       * walking
>>       * still
>>
>> These values are supported by Frescale's MMA9553 sensor:
>>
>> http://freescale.com/files/sensors/doc/ref_manual/MMA9553LSWRM.pdf
>>
>> Signed-off-by: Daniel Baluta <daniel.baluta@intel.com>
>> Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
> Hmm.. This is the interesting one.
> Not immediately obvious how best to represent this stuff.
>> ---
>>  Documentation/ABI/testing/sysfs-bus-iio | 7 +++++++
>>  drivers/iio/industrialio-core.c         | 4 ++++
>>  drivers/iio/industrialio-event.c        | 1 +
>>  include/linux/iio/types.h               | 7 ++++++-
>>  4 files changed, 18 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
>> index d760b02..070346d 100644
>> --- a/Documentation/ABI/testing/sysfs-bus-iio
>> +++ b/Documentation/ABI/testing/sysfs-bus-iio
>> @@ -808,6 +808,13 @@ Description:
>>               number or direction is not specified, applies to all channels of
>>               this type.
>>
>> +What:                /sys/.../events/in_activity_motion_either_en
>> +KernelVersion:       3.17
>> +Contact:     linux-iio@vger.kernel.org
>> +Description:
>> +             Enables or disables motion detection. Each time motion is detected an
>> +             event of this type will be generated.
>> +
> The either bit seems a bit random but I can see there is no particularly obvious
> alternative.
>
> We really need a clean way of representing a multilevel 'state change' like this.
>
> Looking at the event code, I almost wonder if we would be better using the
> direction element for running, walking etc rather than a modifier.
>
> Having said that we will probably also get devices where this is polled rather than
> event.  'What activity is currently going on?'
> If we take that view modifiers make sense as it becomes
> 'Is the user running?'  Perhaps even offering a confidence interval, e.g units as
> percentage
> in_activity_running_input 0..100
> in_activity_walking_input 0..100
> etc
>

This is clear.

> Then our event becomes a state change event (yup we'll need to add that)

So this means we will have a single event type named "state_change"?
Or better "transition".

>
> /events/in_activity_walking_rising_en  will then cause events when the percentage
> confidence on a state rises above the provided threshold or goes above it
> (default of 50% perhaps on devices which only report one state).

Then here the attribute name will be:
/events/in_activity_state_change_walking_rising_en

or if we call the event type "transition" this will be:
/events/in_activity_transition_walking_rising_en

I am a little bit confused :).

>
> /events/in_activity_walking_falling_en will do the leaving case.
>
> Note these are just some quick initial thoughts on alternative methods.
> I'll want to think on this more and get responses from more interested
> parties!
>
>>  What:                /sys/bus/iio/devices/iio:deviceX/trigger/current_trigger
>>  KernelVersion:       2.6.35
>>  Contact:     linux-iio@vger.kernel.org
>> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
>> index 67e8561..e453ef9 100644
>> --- a/drivers/iio/industrialio-core.c
>> +++ b/drivers/iio/industrialio-core.c
>> @@ -92,6 +92,10 @@ static const char * const iio_modifier_names[] = {
>>       [IIO_MOD_NORTH_TRUE] = "from_north_true",
>>       [IIO_MOD_NORTH_MAGN_TILT_COMP] = "from_north_magnetic_tilt_comp",
>>       [IIO_MOD_NORTH_TRUE_TILT_COMP] = "from_north_true_tilt_comp",
>> +     [IIO_MOD_RUNNING] = "running",
>> +     [IIO_MOD_JOGGING] = "jogging",
>> +     [IIO_MOD_WALKING] = "walking",
>> +     [IIO_MOD_STILL] = "still",
>>  };
>>
>>  /* relies on pairs of these shared then separate */
>> diff --git a/drivers/iio/industrialio-event.c b/drivers/iio/industrialio-event.c
>> index 0c1e37e..eca5af2 100644
>> --- a/drivers/iio/industrialio-event.c
>> +++ b/drivers/iio/industrialio-event.c
>> @@ -197,6 +197,7 @@ static const char * const iio_ev_type_text[] = {
>>       [IIO_EV_TYPE_ROC] = "roc",
>>       [IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
>>       [IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
>> +     [IIO_EV_TYPE_MOTION] = "motion",
>>  };
>>
>>  static const char * const iio_ev_dir_text[] = {
>> diff --git a/include/linux/iio/types.h b/include/linux/iio/types.h
>> index d58769a..003638d 100644
>> --- a/include/linux/iio/types.h
>> +++ b/include/linux/iio/types.h
>> @@ -60,7 +60,11 @@ enum iio_modifier {
>>       IIO_MOD_NORTH_MAGN,
>>       IIO_MOD_NORTH_TRUE,
>>       IIO_MOD_NORTH_MAGN_TILT_COMP,
>> -     IIO_MOD_NORTH_TRUE_TILT_COMP
>> +     IIO_MOD_NORTH_TRUE_TILT_COMP,
>> +     IIO_MOD_RUNNING,
>> +     IIO_MOD_JOGGING,
>> +     IIO_MOD_WALKING,
>> +     IIO_MOD_STILL,
>>  };
>>
>>  enum iio_event_type {
>> @@ -69,6 +73,7 @@ enum iio_event_type {
>>       IIO_EV_TYPE_ROC,
>>       IIO_EV_TYPE_THRESH_ADAPTIVE,
>>       IIO_EV_TYPE_MAG_ADAPTIVE,
>> +     IIO_EV_TYPE_MOTION,
>>  };
>>
>>  enum iio_event_info {
>>
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