Re: [PATCH v2 2/3] iio: inv_sensors: better timestamp alignment when using watermark

[Andy Shevchenko <andriy.shevchenko@intel.com>]

On Mon, Jul 20, 2026 at 03:07:05PM +0000, Jean-Baptiste Maneyrol wrote:
> >________________________________________
> >From: Andy Shevchenko <andriy.shevchenko@intel.com>
> >Sent: Monday, July 20, 2026 13:33
> >On Mon, Jul 20, 2026 at 12:38:33PM +0200, Jean-Baptiste Maneyrol via B4 Relay wrote:

...

> >>  void inv_sensors_timestamp_interrupt(struct inv_sensors_timestamp *ts,
> >
> >>       if (sample_nb == 0)
> >>               return;
> >>
> >> +     /* no previous data, compute theoretical value from interrupt */
> >> +     if (ts->timestamp == 0) {
> >> +             /* elapsed time: sensor period * sensor samples number */
> >> +             interval = (s64)ts->period * (s64)sample_nb;
> >
> >The both variables are unsigned. Why do we cast them to the signed type?
> >
> Hello Andy,
> 
> the idea here is to have a (timestamp - interval) doing the difference on
> variables of the same type, s64. I tried to avoid difference between signed
> and unsigned values that can be problematic.
> 
> Interval is s64 for this reason, and that's why I cast the 2 u32 values to
> s64 (which should not be a problem).
> 
> Is that OK like this or do you prefer I change to u64 (with implicit
> conversion to s64 when assigning to interval)?

It was just a question. If you think it's better as is, I'm fine.

> >> +             ts->timestamp = timestamp - interval;
> >> +     }

...

> >> -     /* no previous data, compute theoretical value from interrupt */
> >> -     if (ts->timestamp == 0) {
> >> -             /* elapsed time: sensor period * sensor samples number */
> >> -             interval = (s64)ts->period * (s64)sample_nb;
> >
> >Yeah, I see this is the original code, but consider revisiting.
> >
> >> -             ts->timestamp = it->up - interval;
> >> -             return;
> >> -     }

-- 
With Best Regards,
Andy Shevchenko