I'm currently using a cc6 dual-lite to transfer data between an stm32. Running at 115200 baud over uart with dma, I sometimes miss some bytes. For example I have a test that sends 512 bytes of data 4 times a second. Enabling debug of the imx uart driver shows that it doesn't always get 512 bytes. Sometimes it gets under 512 (eg 500). I would have expected in those cases to see 500 bytes followed by 12 bytes.
Running uart in interrupt mode has no problems but I plan to increase the baud rate up to 1Mbps.