Re: Proposed addition to 'IIO interface' for color light sensing devices

[Jonathan Cameron <jic23@cam.ac.uk>]

Not sure who else would be interested in this discussion so if anyone can cc
any interested parties that would be great! (
> I would like to propose the following addition to the 'IIO device
> interface' for color light sensing devices to accommodate CCT (AKA color
> temperature) and access to the raw RGB channel data for user analysis.
>
> IIO channel type name: CCT
>
> The CCT ABI should be documented similar to as follows:
> In sys-bus-iio-light:
> What:		/sys/bus/iio/devices/device[n]/cct[_input|_raw]
> KernelVersion:	3.3.0
> Contact:	linux-iio@vger.kernel.org
> Description:
> 		This should return the correlated color temperature from
> the RGBC color sensor
> 		expressed as SI unit (degree kelvin).
> 		If it comes back in SI units, it should also
> include_input else it
> 		should include _raw to signify it is not in SI units.
Works for me though the formatting of the above is somewhat different from
our current docs...
>
> IIO modifiers:
> IIO_MOD_LIGHT_RED
> IIO_MOD_LIGHT_GREEN
> IIO_MOD_LIGHT_BLUE
So these modifiers apply to intensity channels?   Colour temp is built from
multiple raw sensors I believe (like illuminance is often done?)
Hence it's another 'virtual' channel we compute?
>
> The 'clear' and IR channels are already covered by the use of IIO_LIGHT
> and IIO ILLUMINANCE (and respective modifiers).
> The RGB modifiers will help to express the relative frequencies to their
> respective channel, and appear to fit well with the overall convention.
>
> And last but not least, the textual modifier names "red", "green", and
> "blue" be accommodated within 'industrialio-core'.
Fine with me.

>
> Channel specific interrupt event / sources are not presented at this
> time.
>
> Any thoughts or comments are welcomed.
>
> Jon Brenner
>
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