Re: [PATCH 3/4] ALSA: CA0132: Add latency monitoring

[Takashi Iwai <tiwai@suse.de>]

At Tue, 2 Apr 2013 13:24:31 -0700,
Dylan Reid wrote:
> 
> On Tue, Apr 2, 2013 at 2:30 AM, Takashi Iwai <tiwai@suse.de> wrote:
> > At Mon, 25 Mar 2013 10:47:31 -0700,
> > Dylan Reid wrote:
> >>
> >> On Sun, Feb 10, 2013 at 2:51 AM, Takashi Iwai <tiwai@suse.de> wrote:
> >> > At Fri, 8 Feb 2013 18:31:44 -0800,
> >> > Ian Minett wrote:
> >> >>
> >> >> From: Ian Minett <ian_minett@creativelabs.com>
> >> >>
> >> >> Add latency monitoring for playback, capture and DSP effects.
> >> >
> >> > Please give a bit more descriptions.
> >> > Looking at the patch, it doesn't implement only the latency monitoring
> >> > but actually reflecting to the runtime->delay.
> >> >
> >> > Also..
> >> >
> >> >
> >> >> Signed-off-by: Ian Minett <ian_minett@creativelabs.com>
> >> >>
> >> >> diff --git a/sound/pci/hda/patch_ca0132.c b/sound/pci/hda/patch_ca0132.c
> >> >> index b52f00c..c797f65 100644
> >> >> --- a/sound/pci/hda/patch_ca0132.c
> >> >> +++ b/sound/pci/hda/patch_ca0132.c
> >> >> @@ -133,6 +133,12 @@ enum {
> >> >>  /* Effects values size*/
> >> >>  #define EFFECT_VALS_MAX_COUNT 12
> >> >>
> >> >> +#define DSP_CAPTURE_INIT_LATENCY        0
> >> >> +#define DSP_CRYSTAL_VOICE_LATENCY       124
> >> >> +#define DSP_PLAYBACK_INIT_LATENCY       13
> >> >> +#define DSP_PLAY_ENHANCEMENT_LATENCY    30
> >> >> +#define DSP_SPEAKER_OUT_LATENCY         7
> >> >> +
> >> >>  struct ct_effect {
> >> >>       char name[44];
> >> >>       hda_nid_t nid;
> >> >> @@ -2761,8 +2767,27 @@ static void ca0132_cleanup_stream(struct hda_codec *codec, hda_nid_t nid)
> >> >>  }
> >> >>
> >> >>  /*
> >> >> - * PCM callbacks
> >> >> + * PCM playbacks
> >> >>   */
> >> >> +static unsigned int ca0132_get_playback_latency(struct hda_codec *codec)
> >> >> +{
> >> >> +     struct ca0132_spec *spec = codec->spec;
> >> >> +     unsigned int latency = DSP_PLAYBACK_INIT_LATENCY;
> >> >> +
> >> >> +     if (!dspload_is_loaded(codec))
> >> >> +             return 0;
> >> >> +
> >> >> +     if (spec->effects_switch[PLAY_ENHANCEMENT - EFFECT_START_NID]) {
> >> >> +             if ((spec->effects_switch[SURROUND - EFFECT_START_NID]) ||
> >> >> +                 (spec->effects_switch[DIALOG_PLUS - EFFECT_START_NID]))
> >> >> +                     latency += DSP_PLAY_ENHANCEMENT_LATENCY;
> >> >> +     }
> >> >> +
> >> >> +     if (spec->cur_out_type == SPEAKER_OUT)
> >> >> +             latency += DSP_SPEAKER_OUT_LATENCY;
> >> >> +     return latency;
> >> >> +}
> >> >> +
> >> >>  static int ca0132_playback_pcm_prepare(struct hda_pcm_stream *hinfo,
> >> >>                       struct hda_codec *codec,
> >> >>                       unsigned int stream_tag,
> >> >> @@ -2770,6 +2795,16 @@ static int ca0132_playback_pcm_prepare(struct hda_pcm_stream *hinfo,
> >> >>                       struct snd_pcm_substream *substream)
> >> >>  {
> >> >>       struct ca0132_spec *spec = codec->spec;
> >> >> +     struct snd_pcm_runtime *runtime = substream->runtime;
> >> >> +     unsigned int latency = ca0132_get_playback_latency(codec);
> >> >> +
> >> >> +     if (spec->dsp_state == DSP_DOWNLOADING) {
> >> >> +             spec->dsp_stream_id = stream_tag;
> >> >> +             return 0;
> >> >> +     }
> >> >> +
> >> >> +     runtime->delay = bytes_to_frames(runtime, (latency * runtime->rate *
> >> >> +                                     runtime->byte_align) / 1000);
> >> >>
> >> >>       ca0132_setup_stream(codec, spec->dacs[0], stream_tag, 0, format);
> >> >>
> >> >> @@ -2834,8 +2869,22 @@ static int ca0132_dig_playback_pcm_close(struct hda_pcm_stream *hinfo,
> >> >>  }
> >> >>
> >> >>  /*
> >> >> - * Analog capture
> >> >> + * PCM capture
> >> >>   */
> >> >> +
> >> >> +static unsigned int ca0132_get_capture_latency(struct hda_codec *codec)
> >> >> +{
> >> >> +     struct ca0132_spec *spec = codec->spec;
> >> >> +     unsigned int latency = DSP_CAPTURE_INIT_LATENCY;
> >> >> +
> >> >> +     if (!dspload_is_loaded(codec))
> >> >> +             return 0;
> >> >> +
> >> >> +     if (spec->effects_switch[CRYSTAL_VOICE - EFFECT_START_NID])
> >> >> +             latency += DSP_CRYSTAL_VOICE_LATENCY;
> >> >> +     return latency;
> >> >> +}
> >> >> +
> >> >>  static int ca0132_capture_pcm_prepare(struct hda_pcm_stream *hinfo,
> >> >>                                       struct hda_codec *codec,
> >> >>                                       unsigned int stream_tag,
> >> >> @@ -2843,9 +2892,16 @@ static int ca0132_capture_pcm_prepare(struct hda_pcm_stream *hinfo,
> >> >>                                       struct snd_pcm_substream *substream)
> >> >>  {
> >> >>       struct ca0132_spec *spec = codec->spec;
> >> >> +     struct snd_pcm_runtime *runtime = substream->runtime;
> >> >> +     unsigned int latency = ca0132_get_capture_latency(codec);
> >> >>
> >> >> -     ca0132_setup_stream(codec, spec->adcs[substream->number],
> >> >> -                         stream_tag, 0, format);
> >> >> +     if (spec->dsp_state == DSP_DOWNLOADING)
> >> >> +             return 0;
> >> >> +
> >> >> +     runtime->delay = bytes_to_frames(runtime, (latency * runtime->rate *
> >> >> +                                     runtime->byte_align) / 1000);
> >> >> +
> >> >> +     ca0132_setup_stream(codec, hinfo->nid, stream_tag, 0, format);
> >> >>
> >> >>       return 0;
> >> >>  }
> >> >> @@ -3429,6 +3485,33 @@ static int ca0132_voicefx_set(struct hda_codec *codec, int enable)
> >> >>       return 1;
> >> >>  }
> >> >>
> >> >> +static void ca0132_update_latency(struct hda_codec *codec,
> >> >> +                               unsigned int direction)
> >> >> +{
> >> >> +     struct ca0132_spec *spec = codec->spec;
> >> >> +     unsigned int latency;
> >> >> +     struct snd_pcm_substream *substr;
> >> >> +     struct snd_pcm_runtime *runtime;
> >> >> +
> >> >> +     if (spec->dsp_state == DSP_DOWNLOADING)
> >> >> +             return;
> >> >> +
> >> >> +     latency = (direction == SNDRV_PCM_STREAM_PLAYBACK)
> >> >> +                     ? ca0132_get_playback_latency(codec)
> >> >> +                     : ca0132_get_capture_latency(codec);
> >> >> +
> >> >> +     substr = codec->pcm_info->pcm->streams[direction].substream;
> >> >> +     while (substr) {
> >> >> +             runtime = substr->runtime;
> >> >> +             /* update latency only when frame_bits is set */
> >> >> +             if (runtime && runtime->frame_bits)
> >> >> +                     runtime->delay = bytes_to_frames(runtime,
> >> >> +                                     (latency * runtime->rate *
> >> >> +                                     runtime->byte_align) / 1000);
> >> >> +             substr = substr->next;
> >> >> +     }
> >> >
> >> > I guess this isn't needed.  Usually the pointer callback is performed
> >> > always before the inquiry of runtime->delay.
> >>
> >> Thanks for pointing that out Takashi.  This will have no effect, as
> >> azx_get_position now recalculates the delay based on LPIB position.
> >>
> >> What was trying to be solved was that there is a large delay in the
> >> codec, and other codecs with integrated DSP.  In this case it is
> >> greater than 100ms, depending on what effects are enabled.  Is there a
> >> good was to add this delay to what is reported?  Maybe allow the codec
> >> to specify a delay that is added to the calculation in
> >> azx_get_position?
> >
> > I'm fine to add a new codec PCM ops for each azx_get_position call
> > if it helps.
> 
> That sounds like the right idea.  I'll take a stab at it and post
> later today.  Thinking something like
> "snd_hda_codec_get_processing_delay()" and a corresponding patch_op.
> Sound right?

Yes.


Takashi