We've been having some issues which we initially thought were "can't be"s (as in, "that can't be happening") with regards to dropping characters on receive over the uarts on the MCF54415. Relatedly, we've seen some odd, rare cases where interrupts can be take ~150us to enter the ISR. I've so far implemented a dma driven DSPI driver (20-100% better throughput over IRQ driven) and recently made an example periodic sampling ADC app using DMA timers. I'm looking into adding DMA to our uart driver to give us a bigger buffers than the 4 byte FIFO in the hardware module, but I can't seem to find anything in the reference manual (version 3 or 4) about how to enable DMA requests instead of interrupts on the UART. Does anyone know the secret I'm missing?