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Commit ef39eb6f authored by Ben Gardiner's avatar Ben Gardiner Committed by Mark Brown
Browse files

ASoC: davinci-pcm: fix audible glitch on 2nd ping-pong playback 



The release of the dma channels was being performed in prepare and there was a
edma_resume call for the asp-channel only being executed on START, RESUME and
PAUSE_RELEASE.

The mcasp on da850evm with ping-pong buffers enabled was exhibiting an audible
glitch on every playback after the first. It was determined through trial and
error that the following two changes fix this problem:

1) Move the edma_start calls from prepare to trigger and 2) reverse the order
of starting the asp and ram channels.

Signed-off-by: default avatarBen Gardiner <bengardiner@nanometrics.ca>
Reviewed-by: default avatarSteven Faludi <stevenfaludi@nanometrics.ca>
Acked-by: default avatarLiam Girdwood <lrg@ti.com>
Signed-off-by: default avatarMark Brown <broonie@opensource.wolfsonmicro.com>
parent acb8e266

sound/soc/davinci/davinci-pcm.c

+7 −6
Original line number Diff line number Diff line
@@ -544,6 +544,13 @@ static int davinci_pcm_trigger(struct snd_pcm_substream *substream, int cmd) 


	switch (cmd) {

	case SNDRV_PCM_TRIGGER_START:

		edma_start(prtd->asp_channel);

		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&

		    prtd->ram_channel >= 0) {

			/* copy 1st iram buffer */

			edma_start(prtd->ram_channel);

		}

		break;

	case SNDRV_PCM_TRIGGER_RESUME:

	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:

		edma_resume(prtd->asp_channel);
@@ -582,11 +589,6 @@ static int davinci_pcm_prepare(struct snd_pcm_substream *substream) 
		print_buf_info(prtd->asp_link[0], "asp_link[0]");

		print_buf_info(prtd->asp_link[1], "asp_link[1]");



		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {

			/* copy 1st iram buffer */

			edma_start(prtd->ram_channel);

		}

		edma_start(prtd->asp_channel);

		return 0;

	}

	prtd->period = 0;
@@ -596,7 +598,6 @@ static int davinci_pcm_prepare(struct snd_pcm_substream *substream) 
	edma_read_slot(prtd->asp_link[0], &prtd->asp_params);

	edma_write_slot(prtd->asp_channel, &prtd->asp_params);

	davinci_pcm_enqueue_dma(substream);

	edma_start(prtd->asp_channel);



	return 0;

}