Re: [PATCH] iio: inv_sensors: fix estimated value larger than interrupt timestamp

[Jonathan Cameron]

On Tue, 25 Aug 2026 13:31:38 +0000
Jean-Baptiste Maneyrol <Jean-Baptiste.Maneyrol@xxxxxxx> wrote:

> >
> >
> >________________________________________
> >From: Andy Shevchenko <andriy.shevchenko@xxxxxxxxx>
> >Sent: Monday, August 24, 2026 17:32
> >To: Jean-Baptiste Maneyrol
> >Cc: Jonathan Cameron; David Lechner; Nuno Sá; Andy Shevchenko; Jonathan Cameron; linux-iio@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; stable@xxxxxxxxxxxxxxx
> >Subject: Re: [PATCH] iio: inv_sensors: fix estimated value larger than interrupt timestamp
> >
> >On Mon, Aug 24, 2026 at 05: 16: 58PM +0200, Jean-Baptiste Maneyrol via B4 Relay wrote: > When interrupt timestamp interval is not valid, we use an estimated value > that can in rare case be bigger than the interrupt timestamp. This is >
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> >On Mon, Aug 24, 2026 at 05:16:58PM +0200, Jean-Baptiste Maneyrol via B4 Relay wrote:
> >  
> >> When interrupt timestamp interval is not valid, we use an estimated value
> >> that can in rare case be bigger than the interrupt timestamp. This is
> >> obviously wrong, so better use interrupt timestamp in this case.  
> >
> >...
> >  
> >> -             ts->period = ts->mult * ts->chip_period.val;
> >> +             ts->period = min(ts->mult * ts->chip_period.val, period);  
> >
> >It's u32 * u32, how is this guaranteed to be always under the u32 result?  
> 
> Hello Andy,
> 
> (ts->mult * ts->chip_period.val) is an estimation of the sampling period of
> the chip in ns. It is limited by maximum setting 8kHz (125000) and minimum
> setting 1.5625Hz (640000000), with a 2% margin. Meaning maximum value is
> 652800000, which is below the 32 bits limit.
> 
> ts->chip_period.val is an estimation of the internal frequency which is 8kHz.
> It's value will always be around 125000, with a 2% margin. Maximum value
> being 127500.
> 
> ts->mult will change from 8kHz setting (1) to 1.5625Hz setting (5120).
> 
> Thanks,
> JB
Seems fine to me so applied to the fixes-togreg branch of iio.git

Thanks

Jonathan

> 
> >
> >--
> >With Best Regards,
> >Andy Shevchenko
> >
> >
> >
>