ASoC: soc-pcm: add option to start DMA after DAI

Add option to start DMA component after DAI trigger. This is done
by filling the new struct snd_soc_component_driver::start_dma_last.
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20230228110145.3770525-2-claudiu.beznea@microchip.comSigned-off-by: Mark Brown <broonie@kernel.org>

include/sound/soc-component.h

@@ -190,6 +190,8 @@ struct snd_soc_component_driver {
 	bool use_dai_pcm_id;	/* use DAI link PCM ID as PCM device number */
 	int be_pcm_base;	/* base device ID for all BE PCMs */
 
+	unsigned int start_dma_last;
+
 #ifdef CONFIG_DEBUG_FS
 	const char *debugfs_prefix;
 #endif

sound/soc/soc-pcm.c

@@ -1088,22 +1088,39 @@ static int soc_pcm_hw_params(struct snd_pcm_substream *substream,
 static int soc_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
 {
 	struct snd_soc_pcm_runtime *rtd = asoc_substream_to_rtd(substream);
-	int ret = -EINVAL, _ret = 0;
+	struct snd_soc_component *component;
+	int ret = -EINVAL, _ret = 0, start_dma_last = 0, i;
 	int rollback = 0;
 
 	switch (cmd) {
 	case SNDRV_PCM_TRIGGER_START:
 	case SNDRV_PCM_TRIGGER_RESUME:
 	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
+		/* Do we need to start dma last? */
+		for_each_rtd_components(rtd, i, component) {
+			if (component->driver->start_dma_last) {
+				start_dma_last = 1;
+				break;
+			}
+		}
+
 		ret = snd_soc_link_trigger(substream, cmd, 0);
 		if (ret < 0)
 			goto start_err;
 
+		if (start_dma_last) {
+			ret = snd_soc_pcm_dai_trigger(substream, cmd, 0);
+			if (ret < 0)
+				goto start_err;
+
+			ret = snd_soc_pcm_component_trigger(substream, cmd, 0);
+		} else {
 			ret = snd_soc_pcm_component_trigger(substream, cmd, 0);
 			if (ret < 0)
 				goto start_err;
 
 			ret = snd_soc_pcm_dai_trigger(substream, cmd, 0);
+		}
 start_err:
 		if (ret < 0)
 			rollback = 1;