ASoC: dmaengine_pcm: Consider DMA cache caused delay in pointer callback

Some DMA engines can have big FIFOs which adds to the latency.
The DMAengine framework can report the FIFO utilization in bytes. Use this
information for the delay reporting.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>

sound/core/pcm_dmaengine.c

@@ -256,9 +256,16 @@ snd_pcm_uframes_t snd_dmaengine_pcm_pointer(struct snd_pcm_substream *substream)
 
 	status = dmaengine_tx_status(prtd->dma_chan, prtd->cookie, &state);
 	if (status == DMA_IN_PROGRESS || status == DMA_PAUSED) {
+		struct snd_pcm_runtime *runtime = substream->runtime;
+		int sample_bytes = snd_pcm_format_physical_width(
+							runtime->format);
+
 		buf_size = snd_pcm_lib_buffer_bytes(substream);
 		if (state.residue > 0 && state.residue <= buf_size)
 			pos = buf_size - state.residue;
+
+		sample_bytes = (sample_bytes / 8) * runtime->channels;
+		runtime->delay = state.in_flight_bytes / sample_bytes;
 	}
 
 	return bytes_to_frames(substream->runtime, pos);

sound/soc/soc-pcm.c

@@ -1208,7 +1208,7 @@ static snd_pcm_uframes_t soc_pcm_pointer(struct snd_pcm_substream *substream)
 	}
 	delay += codec_delay;
 
-	runtime->delay = delay;
+	runtime->delay += delay;
 
 	return offset;
 }