ASoC: SOF: pcm: Improve the pcm trigger sequence

The recommended sequence for triggering the host DMA is to first program
the DMA in the FW before setting the RUN bit to start the stream in the
host. With IPC3, this sequence is honored because the FW programs the
DMA when the HW_PARAMS IPC is sent during PCM hw_params and then the host
sets the RUN bit during sof_pcm_trigger(). But with IPC4,
sof_pcm_trigger() sends the SET_PIPELINE_STATE IPC to program the DMA in
the FW after the DMA RUN bit is set.

In order to minimize the impact for IPC3, introduce a new flag as part
of struct sof_ipc_pcm_ops, ipc_first_on_start, which will be set for IPC4
only. With this flag set, the SET_PIPELINE_STATE IPC will be sent before
the DMA RUN bit is set by the host during the START/PAUSE_RELEASE
triggers.
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Link: https://lore.kernel.org/r/20230322094346.6019-4-peter.ujfalusi@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/ipc4-pcm.c

@@ -835,5 +835,6 @@ const struct sof_ipc_pcm_ops ipc4_pcm_ops = {
 	.dai_link_fixup = sof_ipc4_pcm_dai_link_fixup,
 	.pcm_setup = sof_ipc4_pcm_setup,
 	.pcm_free = sof_ipc4_pcm_free,
-	.delay = sof_ipc4_pcm_delay
+	.delay = sof_ipc4_pcm_delay,
+	.ipc_first_on_start = true
 };

sound/soc/sof/pcm.c

@@ -301,6 +301,8 @@ static int sof_pcm_trigger(struct snd_soc_component *component,
 		ipc_first = true;
 		break;
 	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
+		if (pcm_ops && pcm_ops->ipc_first_on_start)
+			ipc_first = true;
 		break;
 	case SNDRV_PCM_TRIGGER_START:
 		if (spcm->stream[substream->stream].suspend_ignored) {
@@ -312,6 +314,9 @@ static int sof_pcm_trigger(struct snd_soc_component *component,
 			spcm->stream[substream->stream].suspend_ignored = false;
 			return 0;
 		}
+
+		if (pcm_ops && pcm_ops->ipc_first_on_start)
+			ipc_first = true;
 		break;
 	case SNDRV_PCM_TRIGGER_SUSPEND:
 		if (sdev->system_suspend_target == SOF_SUSPEND_S0IX &&
@@ -336,19 +341,28 @@ static int sof_pcm_trigger(struct snd_soc_component *component,
 		return -EINVAL;
 	}
 
-	/*
-	 * DMA and IPC sequence is different for start and stop. Need to send
-	 * STOP IPC before stop DMA
-	 */
 	if (!ipc_first)
 		snd_sof_pcm_platform_trigger(sdev, substream, cmd);
 
 	if (pcm_ops && pcm_ops->trigger)
 		ret = pcm_ops->trigger(component, substream, cmd);
 
-	/* need to STOP DMA even if trigger IPC failed */
-	if (ipc_first)
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
+	case SNDRV_PCM_TRIGGER_START:
+		/* invoke platform trigger to start DMA only if pcm_ops is successful */
+		if (ipc_first && !ret)
+			snd_sof_pcm_platform_trigger(sdev, substream, cmd);
+		break;
+	case SNDRV_PCM_TRIGGER_SUSPEND:
+	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
+	case SNDRV_PCM_TRIGGER_STOP:
+		/* invoke platform trigger to stop DMA even if pcm_ops failed */
 		snd_sof_pcm_platform_trigger(sdev, substream, cmd);
+		break;
+	default:
+		break;
+	}
 
 	/* free PCM if reset_hw_params is set and the STOP IPC is successful */
 	if (!ret && reset_hw_params)

sound/soc/sof/sof-audio.h

@@ -106,6 +106,8 @@ struct snd_sof_dai_config_data {
  * @delay: Function pointer for pcm delay calculation
  * @reset_hw_params_during_stop: Flag indicating whether the hw_params should be reset during the
  *				 STOP pcm trigger
+ * @ipc_first_on_start: Send IPC before invoking platform trigger during
+ *				START/PAUSE_RELEASE triggers
  */
 struct sof_ipc_pcm_ops {
 	int (*hw_params)(struct snd_soc_component *component, struct snd_pcm_substream *substream,
@@ -120,6 +122,7 @@ struct sof_ipc_pcm_ops {
 	snd_pcm_sframes_t (*delay)(struct snd_soc_component *component,
 				   struct snd_pcm_substream *substream);
 	bool reset_hw_params_during_stop;
+	bool ipc_first_on_start;
 };
 
 /**