I managed to deal DMA transfer i tried to put receive a buffer data located in ram from UART and then to transmit back on same uart on request all buffer. with DMA support only and interrupts.
First u must configure the timer but don't start it, second configure the dac for DMA requests.
Afther that enable clock surce from SIM for DMA and DMAMUX and set channel source for DMA channel in your case is the timer surce wich will triger the dma.
Afther that you must set address source wichi will be the file start address and destination address wich will be the address of the DAC register, and the corresponding offsets.
THis is my example
https://community.freescale.com/message/105316#105316