[PATCH 2/6] ASoC: AMD: Reset bytescount when starting transaction

From: Daniel Kurtz
Date: Mon Jul 02 2018 - 17:21:15 EST

The pointer() callback gets its value by reading the I2S BYTE_COUNT
register. This is a 64-bit runnning transaction counter. If a
transaction was aborted in the middle of a sample buffer, the counter will
stop counting on a number divisible by the buffer size. Since we actually
use it as a pointer into an aligned buffer, however, we do want to ensure
that it always starts at a number divisible by the buffer size when
starting a transaction, hence we reset it whenever starting a transaction.

To accomplish this, it wasn't necessary to zero bytescount at the
termination of each transaction, so remove this unnecessary code.

Signed-off-by: Daniel Kurtz <djkurtz@xxxxxxxxxxxx>
sound/soc/amd/acp-pcm-dma.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/sound/soc/amd/acp-pcm-dma.c b/sound/soc/amd/acp-pcm-dma.c
index 4665ae12e74e4..e6f85f2e5ac2a 100644
--- a/sound/soc/amd/acp-pcm-dma.c
+++ b/sound/soc/amd/acp-pcm-dma.c
@@ -1029,7 +1029,6 @@ static int acp_dma_prepare(struct snd_pcm_substream *substream)
static int acp_dma_trigger(struct snd_pcm_substream *substream, int cmd)
int ret;
- u64 bytescount = 0;

struct snd_pcm_runtime *runtime = substream->runtime;
struct audio_substream_data *rtd = runtime->private_data;
@@ -1040,9 +1039,7 @@ static int acp_dma_trigger(struct snd_pcm_substream *substream, int cmd)
- bytescount = acp_get_byte_count(rtd);
- if (rtd->bytescount == 0)
- rtd->bytescount = bytescount;
+ rtd->bytescount = acp_get_byte_count(rtd);
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
acp_dma_start(rtd->acp_mmio, rtd->ch1);
acp_dma_start(rtd->acp_mmio, rtd->ch2);
@@ -1069,7 +1066,6 @@ static int acp_dma_trigger(struct snd_pcm_substream *substream, int cmd)
acp_dma_stop(rtd->acp_mmio, rtd->ch2);
ret = acp_dma_stop(rtd->acp_mmio, rtd->ch1);
- rtd->bytescount = 0;
ret = -EINVAL;