You CANNOT use a blacklist for this! On PowerPC, there is a scaling driver that both supports and doesn't support ondemand, depending on the specific hardware. The ONLY correct solution is the first idea you had, but with a better patch. Combine the gconf stuff from your patch with the patch in Bug #229027, and you'll fix Bug #223812, Bug #229027, and Bug #229672 all in one fell swoop.
You CANNOT use a blacklist for this! On PowerPC, there is a scaling driver that both supports and doesn't support ondemand, depending on the specific hardware. The ONLY correct solution is the first idea you had, but with a better patch. Combine the gconf stuff from your patch with the patch in Bug #229027, and you'll fix Bug #223812, Bug #229027, and Bug #229672 all in one fell swoop.