At Thu, 4 Apr 2013 09:21:34 -0700,
Dylan Reid wrote:
>
> On Thu, Apr 4, 2013 at 12:10 AM, Takashi Iwai <tiwai@xxxxxxx> wrote:
> > At Wed, 3 Apr 2013 08:30:03 -0700,
> > Dylan Reid wrote:
> >>
> >> Allow a codec to specify a delay in addition to the delay before
> >> samples are passed through DMA. Some codecs have large processing
> >> delays because of built-in DSPs that require codec-side buffers of
> >> many milliseconds. Default to zero delay if the codec doesn't specify
> >> a callback to get the processing delay.
> >>
> >> Signed-off-by: Dylan Reid <dgreid@xxxxxxxxxxxx>
> >> ---
> >> sound/pci/hda/hda_codec.c | 17 +++++++++++++++++
> >> sound/pci/hda/hda_codec.h | 4 ++++
> >> sound/pci/hda/hda_intel.c | 2 ++
> >> 3 files changed, 23 insertions(+)
> >>
> >> diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
> >> index 17286b3..1d792dd 100644
> >> --- a/sound/pci/hda/hda_codec.c
> >> +++ b/sound/pci/hda/hda_codec.c
> >> @@ -3724,6 +3724,23 @@ void snd_hda_codec_set_power_to_all(struct hda_codec *codec, hda_nid_t fg,
> >> }
> >> EXPORT_SYMBOL_HDA(snd_hda_codec_set_power_to_all);
> >>
> >> +/**
> >> + * snd_hda_codec_processing_delay - get the fixed delay through the codec
> >> + * @codec: HD-audio codec
> >> + * @stream: playback or capture
> >> + *
> >> + * This is needed for codecs that contain DSPs that cause long delays.
> >> + */
> >> +unsigned int snd_hda_codec_processing_delay(struct hda_codec *codec,
> >> + unsigned int stream)
> >> +{
> >> + if (codec->patch_ops.get_processing_delay)
> >> + return codec->patch_ops.get_processing_delay(codec, stream);
> >> +
> >> + return 0;
> >> +}
> >> +EXPORT_SYMBOL_HDA(snd_hda_codec_processing_delay);
> >
> > In the second thought, it would fit more better to pcm_ops than codec
> > patch_ops. That is, the change would be like below.
>
> Yes this looks better. I'll modify the subsequent patch and run our
> latency tests on it to make sure it works then resend based on this.
I found a missing substream->runtime check (the function may be called
even without running the PCM). The revised patch below was committed
to for-next branch in the end.
thanks,
Takashi
---
From: Takashi Iwai <tiwai@xxxxxxx>
Subject: [PATCH] ALSA: hda - Introduce get_delay codec PCM ops
Add a new codec PCM ops, get_delay(), to obtain the codec/stream-
specific PCM delay count. When it's NULL, nothing changes.
This new feature was requested for CA0132, which has significant
delays in the path depending on the running DSP code.
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
sound/pci/hda/hda_codec.h | 3 +++
sound/pci/hda/hda_intel.c | 18 ++++++++++++++----
2 files changed, 17 insertions(+), 4 deletions(-)
diff --git a/sound/pci/hda/hda_codec.h b/sound/pci/hda/hda_codec.h
index 23ca172..c93f902 100644
--- a/sound/pci/hda/hda_codec.h
+++ b/sound/pci/hda/hda_codec.h
@@ -757,6 +757,9 @@ struct hda_pcm_ops {
struct snd_pcm_substream *substream);
int (*cleanup)(struct hda_pcm_stream *info, struct hda_codec *codec,
struct snd_pcm_substream *substream);
+ unsigned int (*get_delay)(struct hda_pcm_stream *info,
+ struct hda_codec *codec,
+ struct snd_pcm_substream *substream);
};
/* PCM information for each substream */
diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index 418bfc0..735567e 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -2349,8 +2349,11 @@ static unsigned int azx_get_position(struct azx *chip,
struct azx_dev *azx_dev,
bool with_check)
{
+ struct snd_pcm_substream *substream = azx_dev->substream;
+ struct azx_pcm *apcm = snd_pcm_substream_chip(substream);
unsigned int pos;
- int stream = azx_dev->substream->stream;
+ int stream = substream->stream;
+ struct hda_pcm_stream *hinfo = apcm->hinfo[stream];
int delay = 0;
switch (chip->position_fix[stream]) {
@@ -2381,7 +2384,7 @@ static unsigned int azx_get_position(struct azx *chip,
pos = 0;
/* calculate runtime delay from LPIB */
- if (azx_dev->substream->runtime &&
+ if (substream->runtime &&
chip->position_fix[stream] == POS_FIX_POSBUF &&
(chip->driver_caps & AZX_DCAPS_COUNT_LPIB_DELAY)) {
unsigned int lpib_pos = azx_sd_readl(azx_dev, SD_LPIB);
@@ -2399,9 +2402,16 @@ static unsigned int azx_get_position(struct azx *chip,
delay = 0;
chip->driver_caps &= ~AZX_DCAPS_COUNT_LPIB_DELAY;
}
- azx_dev->substream->runtime->delay =
- bytes_to_frames(azx_dev->substream->runtime, delay);
+ delay = bytes_to_frames(substream->runtime, delay);
}
+
+ if (substream->runtime) {
+ if (hinfo->ops.get_delay)
+ delay += hinfo->ops.get_delay(hinfo, apcm->codec,
+ substream);
+ substream->runtime->delay = delay;
+ }
+
trace_azx_get_position(chip, azx_dev, pos, delay);
return pos;
}
--
1.8.1.4
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