Hi Steen
I did try using DMA mode on the Kinetis but had a difficulty with the DMA memory rights so didn't complete that part of the work at the time. In the meantime I think that I know how to solve it but again don't think that it would make much difference due to the fact that the data tranfer rate to the SD card is not critical (I didn't notice any performance advantages using DMA on an NXP ARM so didn't give this any priority). The utFAT interface is a "blocking" interface and so it can't continue until the SD card's write operation has completed; the transfer time is probably just as fast with or without DMA since the CPU doesn't do anything else during the process (only exception would be interrupts taking place but these are also short in comparison). The SD card's serial speed (4 bit width) is limited to about 25MHz (approx. 12MBytes per second) and so the CPU will be able to supply that rate just as well as DMA HW doing it and, as you have also seen, the transfer time is almost neglectible in comparison to the SD card's sector write speed.
Regards
Mark