I don't want to comment on the political issues here, but having worked or at least read a number of software stacks on top of kernel 2.6, I can say that all users of the brightness class interface _I_ have seen are using the max_brightness attribute.
I therefore see no reason to worry about changes, although I clearly want to state that I don't see a reason to change it in the first place. The brightness class interface exposes the hardware capability of a device, which is inherently device specific, that's why max_brightness has been an attribute since this class first hit mainline. Bottom line: Don't change it in kernel. If you decide against my recommendation, don't worry either, userland will not break. Cheers, -- :M:
