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staging: iio: isl29018: add documentation about the infrared suppression

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Add documentation from the ISL29018 Data Sheet (FN6619.4, Oct 8, 2012)
about the infrared suppression that can be controlled
with the proximity_on_chip_ambient_infrared_suppression sysfs attribute.

Signed-off-by: Brian Masney <masneyb@onstation.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Brian Masney 2016-10-06 20:48:34 -04:00 committed by Jonathan Cameron
parent 88efa2baf1
commit e748e2801a
1 changed files with 18 additions and 0 deletions
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18
drivers/staging/iio/light/isl29018.c
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@ -307,6 +307,24 @@ static ssize_t in_illuminance_integration_time_available_show
return len;
}
/*
* From ISL29018 Data Sheet (FN6619.4, Oct 8, 2012) regarding the
* infrared suppression:
*
* Proximity Sensing Scheme: Bit 7. This bit programs the function
* of the proximity detection. Logic 0 of this bit, Scheme 0, makes
* full n (4, 8, 12, 16) bits (unsigned) proximity detection. The range
* of Scheme 0 proximity count is from 0 to 2^n. Logic 1 of this bit,
* Scheme 1, makes n-1 (3, 7, 11, 15) bits (2's complementary)
* proximity_less_ambient detection. The range of Scheme 1
* proximity count is from -2^(n-1) to 2^(n-1) . The sign bit is extended
* for resolutions less than 16. While Scheme 0 has wider dynamic
* range, Scheme 1 proximity detection is less affected by the
* ambient IR noise variation.
*
* 0 Sensing IR from LED and ambient
* 1 Sensing IR from LED with ambient IR rejection
*/
static ssize_t proximity_on_chip_ambient_infrared_suppression_show
(struct device *dev, struct device_attribute *attr,
char *buf)