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

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Message-ID: <aIDriADP9O38eNNT@smile.fi.intel.com>
Date: Wed, 23 Jul 2025 17:02:48 +0300
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: Akshay Jindal <akshayaj.lkd@...il.com>
Cc: anshulusr@...il.com, jic23@...nel.org, dlechner@...libre.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 Tue, Jul 22, 2025 at 01:24:18AM +0530, Akshay Jindal wrote:
> Some IIO sensors provide a status bit indicating whether the current data
> register holds freshly measured data or stale data previously read.
> 
> Expose this status via a new read-only sysfs attribute, 'data_fresh',
> which returns:
>   - 1 if the data is freshly sampled
>   - 0 if the data is stale
> 
> This attribute allows userspace to observe data freshness directly, which
> can be useful for debugging or application-level filtering.
> 
> Document the attribute under Documentation/ABI/testing/sysfs-bus-iio.

> +What:		/sys/.../iio:deviceX/data_fresh
> +KernelVersion:	6.16

No way it can make this version. Neither v6.17 if I understood that this
feature is proposed in this patch.

> +Contact:	linux-iio@...r.kernel.org
> +Description:
> +		Read-only attribute indicating whether the sensor data currently
> +		available in the device is freshly measured or stale.
> +
> +		Returns:
> +			1 - Data is freshly measured
> +			0 - Data is stale (previously read or not yet updated)
> +
> +		Provides userspace visibility into data_freshness status which
> +		can be used for debugging and informational use.

...

>  
> +#define LTR390_DATA_STATUS_MASK		BIT(3)

Missing blank line.

>  /*
>   * At 20-bit resolution (integration time: 400ms) and 18x gain, 2300 counts of
>   * the sensor are equal to 1 UV Index [Datasheet Page#8].

-- 
With Best Regards,
Andy Shevchenko