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

[Andy Shevchenko]

On Mon, Jul 20, 2026 at 12:38:33PM +0200, Jean-Baptiste Maneyrol via B4 Relay wrote:

> Current interrupt timestamp alignment only changes the final timestamp.
> When the watermark is in use, we have a batch of samples for each
> interrupt. The current code doesn't manage to align the timestamp
> because the jitter is too high.
> 
> Instead modify the estimated inter interrupt period and use that to
> adjust the timestamp alignment over the batch in a linear fashion.

...

>  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?

> +		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