[alsa-devel] [PATCH 1/2] ALSA: hda - Add fixed codec delay to runtime delay.

[Takashi Iwai]

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 at chromium.org>
> ---
>  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);
> +
>  /*
>   *  supported power states check
>   */
> diff --git a/sound/pci/hda/hda_codec.h b/sound/pci/hda/hda_codec.h
> index 23ca172..23bd1e7 100644
> --- a/sound/pci/hda/hda_codec.h
> +++ b/sound/pci/hda/hda_codec.h
> @@ -725,6 +725,8 @@ struct hda_codec_ops {
>  	int (*check_power_status)(struct hda_codec *codec, hda_nid_t nid);
>  #endif
>  	void (*reboot_notify)(struct hda_codec *codec);
> +	unsigned int (*get_processing_delay)(struct hda_codec *codec,
> +					     unsigned int stream);
>  };
>  
>  /* record for amp information cache */
> @@ -1063,6 +1065,8 @@ void snd_hda_get_codec_name(struct hda_codec *codec, char *name, int namelen);
>  void snd_hda_bus_reboot_notify(struct hda_bus *bus);
>  void snd_hda_codec_set_power_to_all(struct hda_codec *codec, hda_nid_t fg,
>  				    unsigned int power_state);
> +unsigned int snd_hda_codec_processing_delay(struct hda_codec *codec,
> +					    unsigned int stream);
>  
>  int snd_hda_lock_devices(struct hda_bus *bus);
>  void snd_hda_unlock_devices(struct hda_bus *bus);
> diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> index 418bfc0..422bfaf 100644
> --- a/sound/pci/hda/hda_intel.c
> +++ b/sound/pci/hda/hda_intel.c
> @@ -2349,6 +2349,7 @@ static unsigned int azx_get_position(struct azx *chip,
>  				     struct azx_dev *azx_dev,
>  				     bool with_check)
>  {
> +	struct azx_pcm *apcm = snd_pcm_substream_chip(azx_dev->substream);
>  	unsigned int pos;
>  	int stream = azx_dev->substream->stream;
>  	int delay = 0;
> @@ -2400,6 +2401,7 @@ static unsigned int azx_get_position(struct azx *chip,
>  			chip->driver_caps &= ~AZX_DCAPS_COUNT_LPIB_DELAY;
>  		}
>  		azx_dev->substream->runtime->delay =
> +			snd_hda_codec_processing_delay(apcm->codec, stream) +
>  			bytes_to_frames(azx_dev->substream->runtime, delay);

Isn't this a code path where CA0132 never takes?
It's in the conditional block of AZX_DCAPS_COUNT_LPIB_DELAY.

You need a patch like:

index 418bfc0..5d53eea 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -2399,9 +2399,12 @@ 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(azx_dev->substream->runtime, delay);
 	}
+
+	azx_dev->substream->runtime->delay =
+		delay + snd_hda_codec_processing_delay(apcm->codec, stream);
+
 	trace_azx_get_position(chip, azx_dev, pos, delay);
 	return pos;
 }


Takashi