On Thu, 20 Feb 2025 10:42:27 +0000
Lothar Rubusch <l.rubusch@xxxxxxxxx> wrote:
> Set the suppress bit feature to the double tap detection, whenever
> double tap is enabled.
>
> Any tap event is defined by a rising signal edge above threshold, i.e.
> duration time starts counting; and the falling edge under threshold
> within duration time, i.e. then the tap event is issued. This means
> duration is used individually for each tap event.
>
> For double tap detection after a single tap, a latency time needs to be
> specified. Usually tap events, i.e. spikes above and returning below
> threshold will be ignored within latency. After latency, the window
> time starts counting for a second tap detection which has to happen
> within a duration time.
>
> If the suppress bit is not set, spikes within latency time are ignored.
> Setting the suppress bit will invalidate the double tap function. The
> sensor will thus be able to save the window time for double tap
> detection, and follow a more strict definition of what signal qualifies
> for a double tap.
>
> In a summary having the suppress bit set, fewer signal spikes will be
> considered as double taps. This is an optional add on to double tap,
> thus a separate patch.
>
> Signed-off-by: Lothar Rubusch <l.rubusch@xxxxxxxxx>
> ---
> drivers/iio/accel/adxl345_core.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/drivers/iio/accel/adxl345_core.c b/drivers/iio/accel/adxl345_core.c
> index c014bdf84e66..10cd81dd08bb 100644
> --- a/drivers/iio/accel/adxl345_core.c
> +++ b/drivers/iio/accel/adxl345_core.c
> @@ -34,6 +34,7 @@
> #define ADXL345_INT2 1
>
> #define ADXL345_REG_TAP_AXIS_MSK GENMASK(2, 0)
> +#define ADXL345_REG_TAP_SUPPRESS_MSK BIT(3)
>
> enum adxl345_axis {
> ADXL345_Z_EN = BIT(0),
> @@ -258,6 +259,18 @@ static int adxl345_set_singletap_en(struct adxl345_state *st,
>
> static int adxl345_set_doubletap_en(struct adxl345_state *st, bool en)
> {
> + int ret;
> +
> + /*
> + * generally suppress detection of spikes during the latency period as
Local style has large comments as sentences so capital letter at start and a full stop
at the end preferred.
> + * double taps here, this is fully optional for double tap detection
> + */
> + ret = regmap_update_bits(st->regmap, ADXL345_REG_TAP_AXIS,
> + ADXL345_REG_TAP_SUPPRESS_MSK,
> + en ? ADXL345_TAP_SUPPRESS : 0x00);
> + if (ret)
> + return ret;
> +
> return _adxl345_set_tap_int(st, ADXL345_DOUBLE_TAP, en);
> }
>
