linux-kernel - Re: [PATCH 1/2] iio: light: ltr390: Add sysfs attribute to report data freshness

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Message-ID: <CAE3SzaQcsuHihe2-7VTnXAKYab03Cyu1kAPsA2-E4d1kQzCCNQ@mail.gmail.com>
Date: Thu, 24 Jul 2025 22:25:14 +0530
From: Akshay Jindal <akshayaj.lkd@...il.com>
To: Jonathan Cameron <jic23@...nel.org>
Cc: David Lechner <dlechner@...libre.com>, anshulusr@...il.com, nuno.sa@...log.com, 
	andy@...nel.org, shuah@...nel.org, linux-iio@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] iio: light: ltr390: Add sysfs attribute to report
 data freshness

On Thu, Jul 24, 2025 at 6:09 PM Jonathan Cameron <jic23@...nel.org> wrote:
> Agreed.  Is the interrupt wired on this board?  If it is and you
> want to do filtering with the knowledge that the data is fresh then
> add a data ready trigger and buffered capture support.
> It's a much bigger job, but it is standard ABI and as such of more
> general use.
>
> Jonathan
>
Yes, the interrupt is wired in and enabled.

For LTR390, data_freshness is not the same as data-ready.
Here the sensor does not support a data-ready interrupt.
It only supports threshold violation interrupts where thresholds are
configurable.
LTR390 datasheet Pg 17:
https://optoelectronics.liteon.com/upload/download/DS86-2015-0004/LTR-390UV_Final_%20DS_V1%201.pdf

Correct me, if I am wrong, but as per my understanding, trigger based interrupts
are more appropriate where the application requires storing multiple samples
in a buffer at specific time intervals, provided the sensor supports
data-ready interrupts.

Thanks,
Akshay