New Feature Request in phosphor-pid-control

[Patrick Venture]

The thermal pid controller object only supports one input.  The PID
parameters determine whether its goal is to increase or decrease the
fan speed given a set-point.  My primary usecase was to have the value
as a margin, if the sensor value is 15C, and the setpoint is 10C, then
we're fine because 15 > 10.  However, if it's an absolute temperature
your goal would be the opposite, to speed the fans up until 15 went
down to 10.  Because of these opposite use-cases it wasn't clear what
behavior would be taken with multiple inputs.  We have another program
take dozens of inputs and make one margin value given a configuration,
and that's what is passed down to phosphor-pid-control.

My proposal is to support multiple inputs to the thermal controller
and there will be a new field in the configuration "min" "max" that
will decide the behavior.

Patrick