ASoC: q6asm-dai: add gapless support

Add support to gapless playback by implementing metadata,
next_track, drain and partial drain support.

Gapless on Q6ASM is implemented by opening 2 streams in a single
q6asm stream and toggling them on next track.
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Tested-by: Vinod Koul <vkoul@kernel.org>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Vinod Koul <vkoul@kernel.org>
Link: https://lore.kernel.org/r/20200727093806.17089-10-srinivas.kandagatla@linaro.orgSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/qcom/qdsp6/q6asm-dai.c

@@ -64,11 +64,14 @@ struct q6asm_dai_rtd {
 	uint16_t bits_per_sample;
 	uint16_t source; /* Encoding source bit mask */
 	struct audio_client *audio_client;
+	uint32_t next_track_stream_id;
+	bool next_track;
 	uint32_t stream_id;
 	uint16_t session_id;
 	enum stream_state state;
 	uint32_t initial_samples_drop;
 	uint32_t trailing_samples_drop;
+	bool notify_on_drain;
 };
 
 struct q6asm_dai_data {
@@ -507,13 +510,19 @@ static void compress_event_handler(uint32_t opcode, uint32_t token,
 	struct q6asm_dai_rtd *prtd = priv;
 	struct snd_compr_stream *substream = prtd->cstream;
 	unsigned long flags;
+	u32 wflags = 0;
 	uint64_t avail;
-	uint32_t bytes_written;
+	uint32_t bytes_written, bytes_to_write;
+	bool is_last_buffer = false;
 
 	switch (opcode) {
 	case ASM_CLIENT_EVENT_CMD_RUN_DONE:
 		spin_lock_irqsave(&prtd->lock, flags);
 		if (!prtd->bytes_sent) {
+			q6asm_stream_remove_initial_silence(prtd->audio_client,
+						    prtd->stream_id,
+						    prtd->initial_samples_drop);
+
 			q6asm_write_async(prtd->audio_client, prtd->stream_id,
 					  prtd->pcm_count, 0, 0, 0);
 			prtd->bytes_sent += prtd->pcm_count;
@@ -523,7 +532,30 @@ static void compress_event_handler(uint32_t opcode, uint32_t token,
 		break;
 
 	case ASM_CLIENT_EVENT_CMD_EOS_DONE:
-		prtd->state = Q6ASM_STREAM_STOPPED;
+		spin_lock_irqsave(&prtd->lock, flags);
+		if (prtd->notify_on_drain) {
+			if (substream->partial_drain) {
+				/*
+				 * Close old stream and make it stale, switch
+				 * the active stream now!
+				 */
+				q6asm_cmd_nowait(prtd->audio_client,
+						 prtd->stream_id,
+						 CMD_CLOSE);
+				/*
+				 * vaild stream ids start from 1, So we are
+				 * toggling this between 1 and 2.
+				 */
+				prtd->stream_id = (prtd->stream_id == 1 ? 2 : 1);
+			}
+
+			snd_compr_drain_notify(prtd->cstream);
+			prtd->notify_on_drain = false;
+
+		} else {
+			prtd->state = Q6ASM_STREAM_STOPPED;
+		}
+		spin_unlock_irqrestore(&prtd->lock, flags);
 		break;
 
 	case ASM_CLIENT_EVENT_DATA_WRITE_DONE:
@@ -539,13 +571,32 @@ static void compress_event_handler(uint32_t opcode, uint32_t token,
 		}
 
 		avail = prtd->bytes_received - prtd->bytes_sent;
+		if (avail > prtd->pcm_count) {
+			bytes_to_write = prtd->pcm_count;
+		} else {
+			if (substream->partial_drain || prtd->notify_on_drain)
+				is_last_buffer = true;
+			bytes_to_write = avail;
+		}
+
+		if (bytes_to_write) {
+			if (substream->partial_drain && is_last_buffer) {
+				wflags |= ASM_LAST_BUFFER_FLAG;
+				q6asm_stream_remove_trailing_silence(prtd->audio_client,
+						     prtd->stream_id,
+						     prtd->trailing_samples_drop);
+			}
 
-		if (avail >= prtd->pcm_count) {
 			q6asm_write_async(prtd->audio_client, prtd->stream_id,
-					   prtd->pcm_count, 0, 0, 0);
-			prtd->bytes_sent += prtd->pcm_count;
+					  bytes_to_write, 0, 0, wflags);
+
+			prtd->bytes_sent += bytes_to_write;
 		}
 
+		if (prtd->notify_on_drain && is_last_buffer)
+			q6asm_cmd_nowait(prtd->audio_client,
+					 prtd->stream_id, CMD_EOS);
+
 		spin_unlock_irqrestore(&prtd->lock, flags);
 		break;
 
@@ -625,9 +676,15 @@ static int q6asm_dai_compr_free(struct snd_soc_component *component,
 	struct snd_soc_pcm_runtime *rtd = stream->private_data;
 
 	if (prtd->audio_client) {
-		if (prtd->state)
+		if (prtd->state) {
 			q6asm_cmd(prtd->audio_client, prtd->stream_id,
 				  CMD_CLOSE);
+			if (prtd->next_track_stream_id) {
+				q6asm_cmd(prtd->audio_client,
+					  prtd->next_track_stream_id,
+					  CMD_CLOSE);
+			}
+		}
 
 		snd_dma_free_pages(&prtd->dma_buffer);
 		q6asm_unmap_memory_regions(stream->direction,
@@ -902,6 +959,32 @@ static int q6asm_dai_compr_set_metadata(struct snd_soc_component *component,
 		break;
 	case SNDRV_COMPRESS_ENCODER_DELAY:
 		prtd->initial_samples_drop = metadata->value[0];
+		if (prtd->next_track_stream_id) {
+			ret = q6asm_open_write(prtd->audio_client,
+					       prtd->next_track_stream_id,
+					       prtd->codec.id,
+					       prtd->codec.profile,
+					       prtd->bits_per_sample,
+				       true);
+			if (ret < 0) {
+				dev_err(component->dev, "q6asm_open_write failed\n");
+				return ret;
+			}
+			ret = __q6asm_dai_compr_set_codec_params(component, stream,
+								 &prtd->codec,
+								 prtd->next_track_stream_id);
+			if (ret < 0) {
+				dev_err(component->dev, "q6asm_open_write failed\n");
+				return ret;
+			}
+
+			ret = q6asm_stream_remove_initial_silence(prtd->audio_client,
+						    prtd->next_track_stream_id,
+						    prtd->initial_samples_drop);
+			prtd->next_track_stream_id = 0;
+
+		}
+
 		break;
 	default:
 		ret = -EINVAL;
@@ -935,6 +1018,14 @@ static int q6asm_dai_compr_trigger(struct snd_soc_component *component,
 		ret = q6asm_cmd_nowait(prtd->audio_client, prtd->stream_id,
 				       CMD_PAUSE);
 		break;
+	case SND_COMPR_TRIGGER_NEXT_TRACK:
+		prtd->next_track = true;
+		prtd->next_track_stream_id = (prtd->stream_id == 1 ? 2 : 1);
+		break;
+	case SND_COMPR_TRIGGER_DRAIN:
+	case SND_COMPR_TRIGGER_PARTIAL_DRAIN:
+		prtd->notify_on_drain = true;
+		break;
 	default:
 		ret = -EINVAL;
 		break;

sound/soc/qcom/qdsp6/q6asm.h

@@ -33,6 +33,7 @@ enum {
 
 #define MAX_SESSIONS	8
 #define FORMAT_LINEAR_PCM   0x0000
+#define ASM_LAST_BUFFER_FLAG           BIT(30)
 
 struct q6asm_flac_cfg {
         u32 sample_rate;