linux-kernel - Re: [PATCH v3 2/3] iio: light: ltr390: Add ALS channel and support for gain and resolution

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Message-ID: <20240729205329.57390e20@jic23-huawei>
Date: Mon, 29 Jul 2024 20:53:29 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Abhash Jha <abhashkumarjha123@...il.com>
Cc: linux-iio@...r.kernel.org, anshulusr@...il.com, lars@...afoo.de,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/3] iio: light: ltr390: Add ALS channel and support
 for gain and resolution

On Mon, 29 Jul 2024 17:20:54 +0530
Abhash Jha <abhashkumarjha123@...il.com> wrote:

> Add new ALS channel and allow reading raw and scale values.
> Also provide gain and resolution configuration for ALS channel.
> Add automatic mode switching between the UVS and ALS channel
> based on which channel is being accessed.
> The default mode in which the sensor start is ALS mode.
> 
> Signed-off-by: Abhash Jha <abhashkumarjha123@...il.com>
Hi Abhash,

Patch looks good but one quick question.
Why not present an IIO_LIGHT channel?  Needs to be converted
to be illuminance (with scale / offset applied) rather than IIO_INTENSITY
which we use when the frequency response is different from the requirements
to measure Lux (and the units get very vague!)

Looks like what you have here is close, but not quite the right scale
factor as not including integration time and the mysterious 0.6 on the datasheet.

If we can provide a signal scaled to illuminance that tends to be a lot
more useful for things like screen brightness control because it should
be close at least to other light sensors.

Jonathan