Re: [PATCH 1/2] iio: invensense: better timestamp alignment when using watermark

[Andy Shevchenko]

On Fri, Jul 17, 2026 at 02:39:40PM +0200, Jean-Baptiste Maneyrol via B4 Relay wrote:

> Current interrupt timestamp alignment only change the next coming
> timestamp. For watermark where we have a batch of samples per
> interrupt, it doesn't manage to align timestamp since modification
> is limited because of jitter.
> 
> Implement a better version that instead modify the period to align
> to interrupt timestamp. Period is now computed by align timestamp
> if interrupt interval is valid, or we use the computed estimation.

...

> -/* compute jitter, min and max following jitter in per mille */
> -#define INV_SENSORS_TIMESTAMP_JITTER(_val, _jitter)		\
> -	(div_s64((_val) * (_jitter), 1000))
> +/* compute min and max following jitter in per mille */
>  #define INV_SENSORS_TIMESTAMP_MIN(_val, _jitter)		\
>  	(((_val) * (1000 - (_jitter))) / 1000)

Side note: Just noticed "per mille" for which we now have a constant defined
in units.h :-)

...

> -static void inv_align_timestamp_it(struct inv_sensors_timestamp *ts)
> +static uint32_t inv_align_timestamp_it(struct inv_sensors_timestamp *ts,

Please, use kernel types. u32 here. I think we used to have such a discussion
a year or couple of years ago and become to an agreement that at some point
the types should be changed in the driver before accepting any new changes
to it.

> +				       unsigned int sample_nb)

...

>  	/* if interrupt interval is valid, sync with interrupt timestamp */
> -	if (valid)

Leave this line as is, just add assignment and 'else' branch.

> -		inv_align_timestamp_it(ts);
> +	ts->period = valid ? inv_align_timestamp_it(ts, sample_nb) :
> +			     ts->mult * ts->chip_period.val;
>  }

-- 
With Best Regards,
Andy Shevchenko