dm6467t cannot complete encode 1080p@30fps

I'm trying to use dm6467T complete encode 1080P@30fps, i'm using dvsdk_3_10_11_19 release and h264fhdvenc encoder.  I was able to achieve coding, but only 26fps,now DSP use 660MHz and DDR 270MHz,When I raise dm6467 and DDR PLL register values,such as DSP use 720MHz and DDR 330MHz,My system appears arm926_dma_flush_range error ,what can i do to modify,  Thanks