[PATCH] ASoC: qcom: q6asm-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).
q6asm-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.
Fixes: 2a9e92d371db ("ASoC: qdsp6: q6asm: Add q6asm dai driver") Cc: Srinivas Kandagatla srinivas.kandagatla@linaro.org Signed-off-by: Stephan Gerhold stephan@gerhold.net --- I'm still quite confused about the true meaning of SNDRV_PCM_INFO_BATCH, so please correct me if I'm wrong :)
The tsched=0 workaround can be found in Linaro distributions for QCOM devices for example: - https://git.linaro.org/ci/fai.git/commit/?id=63494268b654d80df033f4cdeccf8f1... - https://github.com/ndechesne/meta-qcom/commit/7035dfeadd1c434fc7613730ac3800...
This patch allows removing that workaround since audio then works without any configuration changes. --- sound/soc/qcom/qdsp6/q6asm-dai.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/sound/soc/qcom/qdsp6/q6asm-dai.c b/sound/soc/qcom/qdsp6/q6asm-dai.c index f6c7cddf08e8..125af00bba53 100644 --- a/sound/soc/qcom/qdsp6/q6asm-dai.c +++ b/sound/soc/qcom/qdsp6/q6asm-dai.c @@ -78,7 +78,7 @@ struct q6asm_dai_data { };
static const struct snd_pcm_hardware q6asm_dai_hardware_capture = { - .info = (SNDRV_PCM_INFO_MMAP | + .info = (SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_BATCH | SNDRV_PCM_INFO_BLOCK_TRANSFER | SNDRV_PCM_INFO_MMAP_VALID | SNDRV_PCM_INFO_INTERLEAVED | @@ -100,7 +100,7 @@ static const struct snd_pcm_hardware q6asm_dai_hardware_capture = { };
static struct snd_pcm_hardware q6asm_dai_hardware_playback = { - .info = (SNDRV_PCM_INFO_MMAP | + .info = (SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_BATCH | SNDRV_PCM_INFO_BLOCK_TRANSFER | SNDRV_PCM_INFO_MMAP_VALID | SNDRV_PCM_INFO_INTERLEAVED |
On 3/30/20 7:52 PM, Stephan Gerhold wrote:
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).q6asm-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.
Fixes: 2a9e92d371db ("ASoC: qdsp6: q6asm: Add q6asm dai driver") Cc: Srinivas Kandagatla srinivas.kandagatla@linaro.org Signed-off-by: Stephan Gerhold stephan@gerhold.net
I'm still quite confused about the true meaning of SNDRV_PCM_INFO_BATCH, so please correct me if I'm wrong :)
The meaning might have changed over the years, but the way it is used right now is that it means that the position pointer has limited granularity. With 'limited' being a bit fuzzy, but typically means that the granularity is worse than a few samples.
This driver definitely falls into the limited category as the granularity seems to be period size.
- Lars
On 3/30/20 1:15 PM, Lars-Peter Clausen wrote:
On 3/30/20 7:52 PM, Stephan Gerhold wrote:
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).
q6asm-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.
Fixes: 2a9e92d371db ("ASoC: qdsp6: q6asm: Add q6asm dai driver") Cc: Srinivas Kandagatla srinivas.kandagatla@linaro.org Signed-off-by: Stephan Gerhold stephan@gerhold.net
I'm still quite confused about the true meaning of SNDRV_PCM_INFO_BATCH, so please correct me if I'm wrong :)
The meaning might have changed over the years, but the way it is used right now is that it means that the position pointer has limited granularity. With 'limited' being a bit fuzzy, but typically means that the granularity is worse than a few samples.
This driver definitely falls into the limited category as the granularity seems to be period size.
Agree, we added this INFO_BATCH flag for SOF Broadwell and Baytrail platforms as well for the same reason of large granularity.
Thanks Stephan for finding this flag!
On 30/03/2020 18:52, Stephan Gerhold wrote:
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).q6asm-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.
Fixes: 2a9e92d371db ("ASoC: qdsp6: q6asm: Add q6asm dai driver") Cc: Srinivas Kandagatla srinivas.kandagatla@linaro.org Signed-off-by: Stephan Gerhold stephan@gerhold.net
Reviewed-by: Srinivas Kandagatla srinivas.kandagatla@linaro.org
The patch
ASoC: qcom: q6asm-dai: Add SNDRV_PCM_INFO_BATCH flag
has been applied to the asoc tree at
https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git
All being well this means that it will be integrated into the linux-next tree (usually sometime in the next 24 hours) and sent to Linus during the next merge window (or sooner if it is a bug fix), however if problems are discovered then the patch may be dropped or reverted.
You may get further e-mails resulting from automated or manual testing and review of the tree, please engage with people reporting problems and send followup patches addressing any issues that are reported if needed.
If any updates are required or you are submitting further changes they should be sent as incremental updates against current git, existing patches will not be replaced.
Please add any relevant lists and maintainers to the CCs when replying to this mail.
Thanks, Mark
From 7f2430cda819a9ecb1df5a0f3ef4f1c20db3f811 Mon Sep 17 00:00:00 2001
From: Stephan Gerhold stephan@gerhold.net Date: Mon, 30 Mar 2020 19:52:10 +0200 Subject: [PATCH] ASoC: qcom: q6asm-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).
q6asm-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.
Fixes: 2a9e92d371db ("ASoC: qdsp6: q6asm: Add q6asm dai driver") Signed-off-by: Stephan Gerhold stephan@gerhold.net Reviewed-by: Srinivas Kandagatla srinivas.kandagatla@linaro.org Cc: Srinivas Kandagatla srinivas.kandagatla@linaro.org Link: https://lore.kernel.org/r/20200330175210.47518-1-stephan@gerhold.net Signed-off-by: Mark Brown broonie@kernel.org --- sound/soc/qcom/qdsp6/q6asm-dai.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/sound/soc/qcom/qdsp6/q6asm-dai.c b/sound/soc/qcom/qdsp6/q6asm-dai.c index f6c7cddf08e8..125af00bba53 100644 --- a/sound/soc/qcom/qdsp6/q6asm-dai.c +++ b/sound/soc/qcom/qdsp6/q6asm-dai.c @@ -78,7 +78,7 @@ struct q6asm_dai_data { };
static const struct snd_pcm_hardware q6asm_dai_hardware_capture = { - .info = (SNDRV_PCM_INFO_MMAP | + .info = (SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_BATCH | SNDRV_PCM_INFO_BLOCK_TRANSFER | SNDRV_PCM_INFO_MMAP_VALID | SNDRV_PCM_INFO_INTERLEAVED | @@ -100,7 +100,7 @@ static const struct snd_pcm_hardware q6asm_dai_hardware_capture = { };
static struct snd_pcm_hardware q6asm_dai_hardware_playback = { - .info = (SNDRV_PCM_INFO_MMAP | + .info = (SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_BATCH | SNDRV_PCM_INFO_BLOCK_TRANSFER | SNDRV_PCM_INFO_MMAP_VALID | SNDRV_PCM_INFO_INTERLEAVED |
participants (5)
-
Lars-Peter Clausen -
Mark Brown -
Pierre-Louis Bossart -
Srinivas Kandagatla -
Stephan Gerhold