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ASoC: qcom: q6apm-dai: Add SNDRV_PCM_INFO_BATCH flag 

At the moment, playing audio with PulseAudio with the qdsp6 driver
results in distorted sound. It seems like its timer-based scheduling
does not work properly with qdsp6 since setting tsched=0 in
the PulseAudio configuration avoids the issue.

Apparently this happens when the pointer() callback is not accurate
enough. There is a SNDRV_PCM_INFO_BATCH flag that can be used to stop
PulseAudio from using timer-based scheduling by default.

According to https://www.alsa-project.org/pipermail/alsa-devel/2014-March/073816.html:

The flag is being used in the sense explained in the previous audio
meeting -- the data transfer granularity isn't fine enough but aligned
to the period size (or less).

q6apm-dai reports the position as multiple of

prtd->pcm_count = snd_pcm_lib_period_bytes(substream)

so it indeed just a multiple of the period size.

Therefore adding the flag here seems appropriate and makes audio
work out of the box.

Comment log inspired by Stephan Gerhold sent for q6asm-dai.c few years back.

Fixes: 9b4fe0f1cd ("ASoC: qdsp6: audioreach: add q6apm-dai support")
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20230209122806.18923-4-srinivas.kandagatla@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Srinivas Kandagatla 2023-02-09 12:28:01 +00:00 committed by Mark Brown
parent 84222ef54b
commit aa759f3f9f
No known key found for this signature in database
GPG Key ID: 24D68B725D5487D0
1 changed files with 4 additions and 2 deletions
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6
sound/soc/qcom/qdsp6/q6apm-dai.c
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@ -64,7 +64,8 @@ struct q6apm_dai_data {
static struct snd_pcm_hardware q6apm_dai_hardware_capture = {
.info = (SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_BLOCK_TRANSFER |
SNDRV_PCM_INFO_MMAP_VALID | SNDRV_PCM_INFO_INTERLEAVED |
SNDRV_PCM_INFO_PAUSE | SNDRV_PCM_INFO_RESUME),
SNDRV_PCM_INFO_PAUSE | SNDRV_PCM_INFO_RESUME |
SNDRV_PCM_INFO_BATCH),
.formats = (SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S24_LE),
.rates = SNDRV_PCM_RATE_8000_48000,
.rate_min = 8000,
@ -82,7 +83,8 @@ static struct snd_pcm_hardware q6apm_dai_hardware_capture = {
static struct snd_pcm_hardware q6apm_dai_hardware_playback = {
.info = (SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_BLOCK_TRANSFER |
SNDRV_PCM_INFO_MMAP_VALID | SNDRV_PCM_INFO_INTERLEAVED |
SNDRV_PCM_INFO_PAUSE | SNDRV_PCM_INFO_RESUME),
SNDRV_PCM_INFO_PAUSE | SNDRV_PCM_INFO_RESUME |
SNDRV_PCM_INFO_BATCH),
.formats = (SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S24_LE),
.rates = SNDRV_PCM_RATE_8000_192000,
.rate_min = 8000,