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 <bengardi...@nanometrics.ca>
Reviewed-by: Steven Faludi <stevenfal...@nanometrics.ca>
CC: Troy Kisky <troy.ki...@boundarydevices.com>
---
sound/soc/davinci/davinci-pcm.c | 13 +++++++------
1 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/sound/soc/davinci/davinci-pcm.c b/sound/soc/davinci/davinci-pcm.c
index 9b5a9bf..5d9269a 100644
--- a/sound/soc/davinci/davinci-pcm.c
+++ b/sound/soc/davinci/davinci-pcm.c
@@ -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;
}
--
1.7.4.1
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