From: Srinivas Kandagatla srinivas.kandagatla@linaro.org
[ Upstream commit aa759f3f9f4394a3af65ad1772fca6cb9dd9e4cc ]
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: 9b4fe0f1cd79 ("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.... Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- sound/soc/qcom/qdsp6/q6apm-dai.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/sound/soc/qcom/qdsp6/q6apm-dai.c b/sound/soc/qcom/qdsp6/q6apm-dai.c index bd35067a40521..7f02f5b2c33fd 100644 --- a/sound/soc/qcom/qdsp6/q6apm-dai.c +++ b/sound/soc/qcom/qdsp6/q6apm-dai.c @@ -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,