ivtv_dma_stream_dec_prepare
ivtv_dma_stream_dec_prepare(s, itv->dma_data_req_offset + IVTV_DECODER_OFFSET, 1);
ivtv_dma_stream_dec_prepare(s, itv->dma_data_req_offset + IVTV_DECODER_OFFSET, 0);
void ivtv_dma_stream_dec_prepare(struct ivtv_stream *s, u32 offset, int lock);