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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: Ben Gardiner <bengardiner@nanometrics.ca>
Reviewed-by: Steven Faludi <stevenfaludi@nanometrics.ca>
Acked-by: Liam Girdwood <lrg@ti.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
hifive-unleashed-5.1
Ben Gardiner 2011-05-24 14:50:18 -04:00 committed by Mark Brown
parent acb8e2666e
commit ef39eb6f21
1 changed files with 7 additions and 6 deletions
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13
sound/soc/davinci/davinci-pcm.c
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@ -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;
}