[PATCH 0/4] iio: light: tsl2591: fix lux calculation and precision, add I2C ID table, report saturation

[Jan Remes <ciakval@gmail.com>]

From: Jan Remes <jan.remes@mycroftmind.com>

This series fixes several issues found while using the TSL2591 in
company products (Raspberry Pi CM5) and when testing (x86_64 laptops
with MCP2221 USB-I2C bridge).

The original field report found that the illumination value has always
been 0.0 (caused by division by zero on ARM).

Patch 1 fixes divisions by zero in the lux calculation, which occur with
LOW gain and short integration times, or in darkness when CH0 = 0.

Patch 2 adds an i2c_device_id table so the driver can be probed on systems
without CONFIG_OF.

Patch 3 makes the driver return an error instead of a bogus value when the
sensor is saturated.

Patch 4 improves the formula for calculating lux values to make the
returned value more accurate.

Patches 3 and 4 change existing behavior, I am OK with splitting the
series into two, if that makes things better.

AI assistance: Claude Code (Claude Opus 5.5) was used for research on
sensor behavior, datasheets and Adafruit library, to compare results
produced by old and new formula, to draft some code for patches 1 and 4.
I reviewed all of it and tested it on x86_64.

Jan Remes (4):
  iio: light: tsl2591: don't divide by zero
  iio: light: tsl2591: add I2C device ID table
  iio: light: tsl2591: report saturation
  iio: light: tsl2591: improve lux calculation precision

 drivers/iio/light/tsl2591.c | 58 +++++++++++++++++++++++++++----------
 1 file changed, 42 insertions(+), 16 deletions(-)


base-commit: a22dc7ebb21a6bd4c8b63bc2c1dd46a24945aae7
-- 
2.53.0