BAPM is a power management feature that handles power budgeting between the CPU/GPUs on APUs. Up to now BAPM has been disabled by default, but for fixing some power-related bugs, this feature is looking to be turned on post-3.16 merge window for some AMD APU hardware.
The BAPM functionality will be enabled by default for Kaveri and Kabini along with Trinity and Richland boards. Besides enabling this power management feature, the latest Radeon Linux 3.16 fixes queue has also some other basic fixes. The main reason for enabling this APU power feature now is to address outstanding bugs. The BAPM support was already found within the Radeon kernel driver but disabled by default as the code still required further work.
The Radeon fixes pull can be found via this pull request, which was already submitted to Linus Torvalds by DRM sub-system maintainer David Airlie.