linux-kernel - Re: [PATCH] ASoC: Intel: Atom: read timestamp moved to period

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Date:   Wed, 10 Jul 2019 16:15:03 -0700
From:   Curtis Malainey <cujomalainey@...gle.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Alex Levin <levinale@...omium.org>,
        ALSA development <alsa-devel@...a-project.org>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Liam Girdwood <liam.r.girdwood@...ux.intel.com>,
        Jie Yang <yang.jie@...ux.intel.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Ben Zhang <benzh@...omium.org>,
        Curtis Malainey <cujomalainey@...omium.org>
Subject: Re: [PATCH] ASoC: Intel: Atom: read timestamp moved to period_elapsed

On Tue, Jul 9, 2019 at 4:45 AM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
>
> On Mon, Jul 08, 2019 at 09:01:47PM -0700, Alex Levin wrote:
> > 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.
>
> From code prospective it looks good. You may take mine
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
>
> Though I'm not an expert in the area, Pierre and / or Liam should give
> their blessing.
>
Agreed, Liam or Pierre should also give their ok since this is one of
the closed source firmware drivers.

Reviewed-by: Curtis Malainey <cujomalainey@...omium.org>
> >
> > Signed-off-by: Alex Levin <levinale@...omium.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
> >
>
> --
> With Best Regards,
> Andy Shevchenko
>
>