The iio_gts helpers build available times and scales tables based on the
times and gains arrays given from the driver. The driver should be able
to list all valid register values so that conversion from register valu
to correct gain/time works for all supported register values.
It might be more convenient for drivers to list these times and gains in
the order where they're listed in the data-sheet than ascending order.
However, for user who requests the supported scales / times it is more
convenient to get the results in asscending order. Also, listing
duplicated values is not meaning for the user.
Hence the GTS heler should do sorting and deduplication of the scales
and times when it builds the tables listing the available times/scales.
Note, currently duplicated gain values aren't handled by GTS-helpers.
Unsort the gain and time arrays in the test code, and add duplicates to
time array in order to test the sorting and deduplicating works.
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://lore.kernel.org/r/365cc6de3c17a457db738f5fdf8dd3bd6f50d5f2.1714480171.git.mazziesaccount@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Some light sensors can adjust both the HW-gain and integration time.
There are cases where adjusting the integration time has similar impact
to the scale of the reported values as gain setting has.
IIO users do typically expect to handle scale by a single writable 'scale'
entry. Driver should then adjust the gain/time accordingly.
It however is difficult for a driver to know whether it should change
gain or integration time to meet the requested scale. Usually it is
preferred to have longer integration time which usually improves
accuracy, but there may be use-cases where long measurement times can be
an issue. Thus it can be preferable to allow also changing the
integration time - but mitigate the scale impact by also changing the gain
underneath. Eg, if integration time change doubles the measured values,
the driver can reduce the HW-gain to half.
The theory of the computations of gain-time-scale is simple. However,
some people (undersigned) got that implemented wrong for more than once.
Hence some gain-time-scale helpers were introduced.
Add some simple tests to verify the most hairy functions.
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://lore.kernel.org/r/0f7505b43f91394dc3bb636369489c897b7e01a7.1705328293.git.mazziesaccount@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
