dma_hwdesc_addr
desc->next = dma_hwdesc_addr(priv, next_hwdesc);
regmap_write(priv->map, JZ_REG_LCD_DA0, dma_hwdesc_addr(priv, next_id));
regmap_write(priv->map, JZ_REG_LCD_DA1, dma_hwdesc_addr(priv, 1));
hwdesc->next = dma_hwdesc_addr(priv, next_id);