Re: [RFC PATCH 3/4] iio: accel: fxls8962af: add hw buffered sampling

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Thu, 29 Apr 2021 09:40:00 +0200
Sean Nyekjaer <sean@geanix.com> wrote:

> On 28/04/2021 18.32, Jonathan Cameron wrote:
> >> When buffered sampling is enabled, the accelerometer will dump data into
> >> the internal fifo and interrupt at watermark. Then the driver flushes
> >> all data to the iio buffer.
> >> As the accelerometer doesn't have internal timestamps, they are aproximated
> >> between to interrupts.  
> > two?
> >
> > This tends to be a noisy approach, so people often try to apply a filter.
> > However, no need to do that for an initial version.
> >
> > There are some things in here referring to enabling triggered modes, but I'm
> > not seeing code to actually do so.  The fun question when dealing with fifos
> > and triggered mode is what the interface is to switch between the two.
> > One option I think we've used before is to just have 'no trigger' match
> > up to fifo mode and if a trigger is set, don't use the fifo.
> >  
> Thanks Jonathan.
> 
> Fixed the above text to:
> As the accelerometer doesn't have internal timestamps,
> they are approximated between the current and last interrupt.
Nice.

> 
> I don't know the correct term here, the accelerometer via the watermark, 
> is doing interrupts.
> Is that called no-trigger / trigger ?

Triggers are one per scan (Set of samples take at approximately the same time)
So anything involving a fifo is without trigger (we don't expose anything because
it is of no use for doing synchronous capture across multiple devices).

One day I'll add a terminology section to the docs!

J

> 
> /Sean