I do not get any audio output with my Focusrite Scarlett 18i8 with any of the 4. kernels from Fedora or CCRMA.  The audio input works and all the audio I/O ports are visible in jack and pulseaudio.  Audio output still works with kernel 3.18.9-201.rt5.1.fc21.ccrma.x86_64, the only 3. kernel left on my computer.