[PATCH] ASoC: Intel: Atom: read timestamp moved to period_elapsed

[Alex Levin]

sst_platform_pcm_pointer is called from both snd_pcm_period_elapsed and
from snd_pcm_ioctl. Calling read timestamp results in recalculating
pcm_delay and buffer_ptr (sst_calc_tstamp) which consumes buffers in a
faster rate than intended.
In a tested BSW system with chtrt5650, for a rate of 48000, the
measured rate was sometimes 10 times more than that.
After moving the timestamp read to period elapsed, buffer consumption is
as expected.

Signed-off-by: Alex Levin <levin...@chromium.org>
---
 sound/soc/intel/atom/sst-mfld-platform-pcm.c | 23 +++++++++++++-------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/sound/soc/intel/atom/sst-mfld-platform-pcm.c 
b/sound/soc/intel/atom/sst-mfld-platform-pcm.c
index 0e8b1c5eec88..196af0b30b41 100644
--- a/sound/soc/intel/atom/sst-mfld-platform-pcm.c
+++ b/sound/soc/intel/atom/sst-mfld-platform-pcm.c
@@ -265,16 +265,28 @@ static void sst_period_elapsed(void *arg)
 {
        struct snd_pcm_substream *substream = arg;
        struct sst_runtime_stream *stream;
-       int status;
+       struct snd_soc_pcm_runtime *rtd;
+       int status, ret_val;
 
        if (!substream || !substream->runtime)
                return;
        stream = substream->runtime->private_data;
        if (!stream)
                return;
+
+       rtd = substream->private_data;
+       if (!rtd)
+               return;
+
        status = sst_get_stream_status(stream);
        if (status != SST_PLATFORM_RUNNING)
                return;
+
+       ret_val = stream->ops->stream_read_tstamp(sst->dev, 
&stream->stream_info);
+       if (ret_val) {
+               dev_err(rtd->dev, "stream_read_tstamp err code = %d\n", 
ret_val);
+               return;
+       }
        snd_pcm_period_elapsed(substream);
 }
 
@@ -658,20 +670,15 @@ static snd_pcm_uframes_t sst_platform_pcm_pointer
                        (struct snd_pcm_substream *substream)
 {
        struct sst_runtime_stream *stream;
-       int ret_val, status;
+       int status;
        struct pcm_stream_info *str_info;
-       struct snd_soc_pcm_runtime *rtd = substream->private_data;
 
        stream = substream->runtime->private_data;
        status = sst_get_stream_status(stream);
        if (status == SST_PLATFORM_INIT)
                return 0;
+
        str_info = &stream->stream_info;
-       ret_val = stream->ops->stream_read_tstamp(sst->dev, str_info);
-       if (ret_val) {
-               dev_err(rtd->dev, "sst: error code = %d\n", ret_val);
-               return ret_val;
-       }
        substream->runtime->delay = str_info->pcm_delay;
        return str_info->buffer_ptr;
 }
-- 
2.22.0.410.gd8fdbe21b5-goog