Could we just say this is always true because state[i+1] consumes less than state[i] ?
And then just remove the 'set_power_state' function, and the field 'driver->power_specified' ?
That will cleanup the code and fix this problem, no ?
I totally agree with your analysis. Even if a driver were to set proper usage values (and the power_specified bit), none of the existing governors would care about those actual numbers (and since the vast majority of drivers uses fake values anyway, this is not likely to change in the future). This seems to be a classic example of unnecessary over-engineering.
I am mostly interested in getting that bug fixed right now, but removing unnecessary code is always a good thing. If you think it would have a good chance of getting merged, I would be happy to draft up a larger patch that refactors power_usage away completely.