Hi Andy,
This is a tricky one, I'll give some examples why (I think) the code
is needed as is.
On Mon, Jun 23, 2025 at 12:17 PM Andy Shevchenko
<andriy.shevchenko@xxxxxxxxx> wrote:
>
> On Sun, Jun 22, 2025 at 03:50:09PM +0000, Lothar Rubusch wrote:
> > Inactivity and free-fall events are essentially the same type of sensor
> > events. Therefore, inactivity detection (normally set for periods between 1
> > and 255 seconds) can be extended for shorter durations to support free-fall
> > detection.
> >
> > For periods shorter than 1 second, the driver automatically configures the
> > threshold and duration using the free-fall register. For periods longer
> > than 1 second, it uses the inactivity threshold and duration using the
> > inactivity registers.
> >
> > When using the free-fall register, the link bit is not set, which means
> > auto-sleep cannot be enabled if activity detection is also active.
>
> ...
>
> > -static int adxl345_set_inact_time(struct adxl345_state *st, u32 val_s)
> > +static int adxl345_set_inact_time(struct adxl345_state *st, u32 val_int,
> > + u32 val_fract)
> > {
> > int max_boundary = U8_MAX;
> > int min_boundary = 10;
> > - unsigned int val = min(val_s, U8_MAX);
> > + unsigned int val;
>
> You see, I even suggested splitting this assignment to begin with.
> The change will be clearer with that done.
>
> > enum adxl345_odr odr;
> > unsigned int regval;
> > int ret;
> >
> > - if (val == 0) {
> > + if (val_int == 0 && val_fract == 0) {
The case for 0sec, 0.0 or setting "0" and fract will consequently be
"0". 0 is an invalid input for this period and sensor, so it will
default to an optimized period based on given ODR.
> > + /* Generated inactivity time based on ODR */
> > ret = regmap_read(st->regmap, ADXL345_REG_BW_RATE, ®val);
> > if (ret)
> > return ret;
>
> > odr = FIELD_GET(ADXL345_BW_RATE_MSK, regval);
> > val = clamp(max_boundary - adxl345_odr_tbl[odr][0],
> > min_boundary, max_boundary);
> > + st->inact_time_ms = MILLI * val;
> > +
> > + /* Inactivity time in s */
> > + return regmap_write(st->regmap, ADXL345_REG_TIME_INACT, val);
> > + } else if (val_int == 0 && val_fract > 0) {
>
> val_fract check is not needed here.
>
Case for e.g. 0.123, numbers under 1s. This goes into the free-fall register.
> > + /* time < 1s, free-fall */
> > +
> > + /*
> > + * Datasheet max. value is 255 * 5000 us = 1.275000 seconds.
> > + *
> > + * Recommended values between 100ms and 350ms (0x14 to 0x46)
> > + */
> > + st->inact_time_ms = DIV_ROUND_UP(val_fract, MILLI);
> > +
> > + return regmap_write(st->regmap, ADXL345_REG_TIME_FF,
> > + DIV_ROUND_CLOSEST(val_fract, 5));
> > + } else if (val_int > 0) {
>
> if now is redundant here, right?
>
So, this will be 1s through 255s. Periods above 1sec. This goes into
the inactivity register.
> > + /* Time >= 1s, inactivity */
> > + st->inact_time_ms = MILLI * val_int;
> > +
> > + return regmap_write(st->regmap, ADXL345_REG_TIME_INACT, val_int);
> > }
> >
> > - return regmap_write(st->regmap, ADXL345_REG_TIME_INACT, val);
> > + /* Do not support negative or wrong input. */
> > + return -EINVAL;
> > }
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
