Matthew,
I actually removed the opp-modifier table from my device tree for now. Along with doing that, I am able to add any opp tuple to the opp table in the device tree and the kernel seems to configure it. For example, running at 50MHZ draws less current than at 100MHZ , which draws less than at 150MHZ, and so on. (For testing, I'm using the same voltage values for each opp).
Having said that, I'm not sure how the kernel is actually calculating the clock control register values. At first I assumed that discrete opp values were being defined somewhere, but that seems to not be the case. I even tested using an opp of 1 KHz just to see what would happen. The kernel struggled to finish booting and the uart interface was really delayed, but it worked. The point is, I'm not sure what kind of rounding is going on between user defined opp frequency values and the real mpu frequency that gets set. I wish I knew how to measure or locate the actual mpu frequency.
Cheers,
Nolan