TODO for slave dma 1. Move remaining drivers to use new slave interface 2. Remove old slave pointer machansim 3. Make issue_pending to start the transaction in below drivers - mpc512x_dma - imx-dma - imx-sdma - mxs-dma.c - dw_dmac - intel_mid_dma 4. Check other subsystems for dma drivers and merge/move to dmaengine 5. Remove dma_slave_config's dma direction.