Re: [PATCH 1/3] iio: mma8452: add freefall detection for Freescale's accelerometers

Martin Kepplinger
2015-11-24T05:21:27Z

Am 2015-11-17 um 20:24 schrieb Martin Kepplinger:
> Am 2015-11-14 um 20:03 schrieb Jonathan Cameron:
>> On 14/11/15 18:45, Martin Kepplinger wrote:
>>> Am 2015-11-14 um 19:03 schrieb Jonathan Cameron:
>>>> On 11/11/15 18:38, Martin Kepplinger wrote:
>>>>> This adds freefall event detection to the supported devices. It adds
>>>>> the in_accel_x&y&z_mag_falling_en iio event attribute, which activates
>>>>> freefall mode.
>>>>>
>>>>> In freefall mode, the current acceleration values of all activated axis
>>>>> are added and if the *sum* falls *under* the threshold specified
>>>>> (in_accel_mag_falling_value), the appropriate IIO event code
>>>>> is generated.
>>>>>
>>>>> By enabling freefall mode (in_accel_x&y&z_mag_falling_en)
>>>>> all 3 axis are enabled too as this describes a classic freefall
>>>>> detection. Of course the user is free to disable one or more directions.
>>>>>
>>>>> The values of rising and falling versions of various sysfs files are
>>>>> shared, which is compliant to the IIO specification.
>>>>>
>>>>> This is what the sysfs "events" directory for these devices looks
>>>>> like after this change:
>>>>>
>>>>> -rw-r--r-- 4096 Oct 23 08:45 in_accel_mag_falling_period
>>>>> -rw-r--r-- 4096 Oct 23 08:45 in_accel_mag_falling_value
>>>>> -rw-r--r-- 4096 Oct 23 08:45 in_accel_mag_rising_period
>>>>> -rw-r--r-- 4096 Oct 23 08:45 in_accel_mag_rising_value
>>>>> -r--r--r-- 4096 Oct 23 08:45 in_accel_scale
>>>>> -rw-r--r-- 4096 Oct 23 08:45 in_accel_x&y&z_mag_falling_en
>>>>> -rw-r--r-- 4096 Oct 23 08:45 in_accel_x_mag_falling_en
>>>>> -rw-r--r-- 4096 Oct 23 08:45 in_accel_x_mag_rising_en
>>>>> -rw-r--r-- 4096 Oct 23 08:45 in_accel_y_mag_falling_en
>>>>> -rw-r--r-- 4096 Oct 23 08:45 in_accel_y_mag_rising_en
>>>>> -rw-r--r-- 4096 Oct 23 08:45 in_accel_z_mag_falling_en
>>>>> -rw-r--r-- 4096 Oct 23 08:45 in_accel_z_mag_rising_en
>>>>>
>>>>> Signed-off-by: Martin Kepplinger <martin.kepplinger@theobroma-systems.com>
>>>>> Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
>>>> Looks pretty good to me (other than obviously the bits Lars already
>>>> picked up on!)
>>>>
>>>> My only real comment was that you could do the rest of the combined
>>>> possibilities whilst you are here (if you want to!) You've
>>>> picked the mostly obviously useful one though so maybe leave it
>>>> at that.
>>>
>>> I'm not sure what you mean. There is only in_accel_x&y&z_mag_falling_en
>>> documented. So my guess was to have this to enable freefall mode, taking
>>> into account the currently enabled falling axis
>>> (in_accel_x_mag_falling_en, ...).
>> Sure, but the set of modifiers allows for
>> in_accel_x&y_mag_falling_* etc and they aren't documented in this particular
>> form simply because no driver has used them yet ;)
>>
>
>
>
> I don't see how to do it in iio_event_spec only. Could you point me in
> the right direction, could well be I overlook something...
>
> I *can* add a channel for freefall purposes, something like:
>
> static const struct iio_chan_spec mma8653_channels[] = {
> MMA8652_CHANNEL(IIO_MOD_X, idx_axis_x, 10),
> MMA8652_CHANNEL(IIO_MOD_Y, idx_axis_y, 10),
> MMA8652_CHANNEL(IIO_MOD_Z, idx_axis_z, 10),
> MMA8652_CHANNEL(IIO_MOD_X_AND_Y_AND_Z, idx_axis_xyz, 10),
> IIO_CHAN_SOFT_TIMESTAMP(idx_timestamp),
> };
>
>
> just as an example, but then of course I get more than just events: In
> the device-directory:
>
> in_accel_x&y&z_calibbias
> in_accel_x&y&z_raw
> in_accel_x_calibbias
> in_accel_x_raw
> in_accel_y_calibbias
> in_accel_y_raw
> in_accel_z_calibbias
> in_accel_z_raw
>
>
> calibbias and raw are not (really) available for x&y&z. I could
> calculate a "raw" value, but calibbias doesn't make sense here. ...But
> again, maybe I'm on the wrong path!!
>
> thanks a lot!
>
> martin
>

Would this be the way to go? And just not support the generated file
that don't apply?

thanks,

martin