On 12/4/23 12:29, Jonathan Cameron wrote:
On Mon, 27 Nov 2023 22:26:53 +0100
Marek Vasut <marex@xxxxxxx> wrote:
The ISL76682 is very basic ALS which only supports ALS or IR mode
in four ranges, 1k/4k/16k/64k LUX. There is no IRQ support or any
other fancy functionality.
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Reviewed-by: Matti Vaittinen <mazziesaccount@xxxxxxxxx>
Signed-off-by: Marek Vasut <marex@xxxxxxx>
There is a additional question on what scale means for
an IR channel. There aren't any well defined units (as it depends
on the sensitivity curve) so in general we avoid providing scale
for intensity readings.
The datasheet has a vague go at working around this problem by
using counts relative to IR measurement in daylight which would
measure 210 LUX. (via faking that with a 850nm green led??)
That's far from a standard..
We do have precedence of scale applied to intensity channels
so I guess the ship has sailed.
Perhaps we should just add an explicit not to the ABI docs
to cover that changing the scale in these sensors will result
in the counts changing, but multiplying raw by scale isn't going
to give any sensible units.
So probably not a thing to fix in this series, but to address
separately.
Is something like this what you have in mind ?
diff --git a/Documentation/ABI/testing/sysfs-bus-iio
b/Documentation/ABI/testing/sysfs-bus-iio
index 0eadc08c3a139..584607f560d02 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -618,7 +618,9 @@ KernelVersion: 2.6.35
Contact: linux-iio@xxxxxxxxxxxxxxx
Description:
If a discrete set of scale values is available, they
- are listed in this attribute.
+ are listed in this attribute. Unlike illumination,
+ multiplying intensity by intensity_scale does not
+ yield value with any standardized unit .
What: /sys/bus/iio/devices/iio:deviceX/out_voltageY_hardwaregain
What: /sys/bus/iio/devices/iio:deviceX/in_intensity_hardwaregain
