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

[Jonathan Cameron]

Jon Brenner <jbrenner@xxxxxxxxxxx> wrote:

>Replies in-line,
>
>
>> -----Original Message-----
>> From: Jonathan Cameron [mailto:jic23@xxxxxxxxx]
>> Sent: Wednesday, April 04, 2012 3:40 AM
>> To: Jon Brenner
>> Cc: jic23@xxxxxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx;
>linux-iio@xxxxxxxxxxxxxxx;
>> linux-kernel@xxxxxxxxxxxxxxx
>> Subject: Re: Proposed addition to 'IIO interface' for color light
>sensing devices
>> 
>> 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@xxxxxxxxxxxxxxx
>> > 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?
>Yes.
>At channel 0 - correct?
Yup. It is the first illuminance channel.
>
>So we now have illuminance0_input and in_cct0 - correct?
Should be in_illuminance0_input and in_cct0_input
Otherwise yes.  Maybe don't skimp on chars and have in_colourtemp_input 
>
>Clear uses chan 0 and as before, chan 1 - so as before intensityN_raw
>mapped to both - correct?
Don't necessarily need indexes if using modifiers. We don't bother for inertial sensors... event codes include modifiers so they are optional.  Channel can have index or modifier or both...
>
>Red is channel 1 - so we have in_intensity1_red_raw -  correct?
>
>Green = intensity2_green_raw.. and so on correct?
>> >
>> > 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.
>> 
>
>Proximity remains at channel 0 correct?
Yes
>
>
>> >
>> > Channel specific interrupt event / sources are not presented at
>this
>> > time.
>> >
>> > Any thoughts or comments are welcomed.
>> >
>> > Jon Brenner
>> >
>> > --
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