[PATCH 0/2] Fixes for McASP and dmaengine_pcm

[PATCH 0/2] Fixes for McASP and dmaengine_pcm

[Jai Luthra]

This series fixes two patches:

1. Fix the dmaengine API usage by calling dmaengine_synchronize() after
   dmaengine_terminate_async() when xrun events occur in application
2. Use the McASP AFIFO property from DT to refine the period size,
   instead of hardcoding minimum to 64 samples

Signed-off-by: Jai Luthra <j-luthra@ti.com>
---
Jai Luthra (2):
      ALSA: dmaengine: Synchronize dma channel in prepare()
      ASoC: ti: davinci-mcasp: Set min period size using FIFO config

 include/sound/dmaengine_pcm.h         |  1 +
 sound/core/pcm_dmaengine.c            | 10 ++++++++++
 sound/soc/soc-generic-dmaengine-pcm.c |  8 ++++++++
 sound/soc/ti/davinci-mcasp.c          |  9 +++++++--
 4 files changed, 26 insertions(+), 2 deletions(-)
---
base-commit: d97496ca23a2d4ee80b7302849404859d9058bcd
change-id: 20240604-asoc_next-c063fcc190c6

Best regards,
-- 
Jai Luthra <j-luthra@ti.com>

[PATCH 1/2] ALSA: dmaengine: Synchronize dma channel in prepare()

[Jai Luthra]

Sometimes the stream may be stopped due to XRUN events, in which case
the userspace can call snd_pcm_drop() and snd_pcm_prepare() to stop and
start the stream again.

In these cases, we must wait for the DMA channel to synchronize before
marking the stream as prepared for playback, as the DMA channel gets
stopped by snd_pcm_drop() without any synchronization.

Signed-off-by: Jai Luthra <j-luthra@ti.com>
---
 include/sound/dmaengine_pcm.h         |  1 +
 sound/core/pcm_dmaengine.c            | 10 ++++++++++
 sound/soc/soc-generic-dmaengine-pcm.c |  8 ++++++++
 3 files changed, 19 insertions(+)

diff --git a/include/sound/dmaengine_pcm.h b/include/sound/dmaengine_pcm.h
index c11aaf8079fb..9c5800e5659f 100644
--- a/include/sound/dmaengine_pcm.h
+++ b/include/sound/dmaengine_pcm.h
@@ -36,6 +36,7 @@ snd_pcm_uframes_t snd_dmaengine_pcm_pointer_no_residue(struct snd_pcm_substream
 int snd_dmaengine_pcm_open(struct snd_pcm_substream *substream,
 	struct dma_chan *chan);
 int snd_dmaengine_pcm_close(struct snd_pcm_substream *substream);
+int snd_dmaengine_pcm_prepare(struct snd_pcm_substream *substream);
 
 int snd_dmaengine_pcm_open_request_chan(struct snd_pcm_substream *substream,
 	dma_filter_fn filter_fn, void *filter_data);
diff --git a/sound/core/pcm_dmaengine.c b/sound/core/pcm_dmaengine.c
index 12aa1cef11a1..dbf5c6136d68 100644
--- a/sound/core/pcm_dmaengine.c
+++ b/sound/core/pcm_dmaengine.c
@@ -349,6 +349,16 @@ int snd_dmaengine_pcm_open_request_chan(struct snd_pcm_substream *substream,
 }
 EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_open_request_chan);
 
+int snd_dmaengine_pcm_prepare(struct snd_pcm_substream *substream)
+{
+	struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);
+
+	dmaengine_synchronize(prtd->dma_chan);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_prepare);
+
 /**
  * snd_dmaengine_pcm_close - Close a dmaengine based PCM substream
  * @substream: PCM substream
diff --git a/sound/soc/soc-generic-dmaengine-pcm.c b/sound/soc/soc-generic-dmaengine-pcm.c
index ea3bc9318412..af439486d33a 100644
--- a/sound/soc/soc-generic-dmaengine-pcm.c
+++ b/sound/soc/soc-generic-dmaengine-pcm.c
@@ -318,6 +318,12 @@ static int dmaengine_copy(struct snd_soc_component *component,
 	return 0;
 }
 
+int dmaengine_pcm_prepare(struct snd_soc_component *component,
+			  struct snd_pcm_substream *substream)
+{
+	return snd_dmaengine_pcm_prepare(substream);
+}
+
 static const struct snd_soc_component_driver dmaengine_pcm_component = {
 	.name		= SND_DMAENGINE_PCM_DRV_NAME,
 	.probe_order	= SND_SOC_COMP_ORDER_LATE,
@@ -327,6 +333,7 @@ static const struct snd_soc_component_driver dmaengine_pcm_component = {
 	.trigger	= dmaengine_pcm_trigger,
 	.pointer	= dmaengine_pcm_pointer,
 	.pcm_construct	= dmaengine_pcm_new,
+	.prepare	= dmaengine_pcm_prepare,
 };
 
 static const struct snd_soc_component_driver dmaengine_pcm_component_process = {
@@ -339,6 +346,7 @@ static const struct snd_soc_component_driver dmaengine_pcm_component_process = {
 	.pointer	= dmaengine_pcm_pointer,
 	.copy		= dmaengine_copy,
 	.pcm_construct	= dmaengine_pcm_new,
+	.prepare	= dmaengine_pcm_prepare,
 };
 
 static const char * const dmaengine_pcm_dma_channel_names[] = {

-- 
2.43.0

[PATCH 2/2] ASoC: ti: davinci-mcasp: Set min period size using FIFO config

[Jai Luthra]

The minimum period size was enforced to 64 as older devices integrating
McASP with EDMA used an internal FIFO of 64 samples.

With UDMA based platforms this internal McASP FIFO is optional, as the
DMA engine internally does some buffering which is already accounted for
when registering the platform. So we should read the actual FIFO
configuration (txnumevt/rxnumevt) instead of hardcoding frames.min to
64.

Signed-off-by: Jai Luthra <j-luthra@ti.com>
---
 sound/soc/ti/davinci-mcasp.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/sound/soc/ti/davinci-mcasp.c b/sound/soc/ti/davinci-mcasp.c
index 1e760c315521..2a53fb7e72eb 100644
--- a/sound/soc/ti/davinci-mcasp.c
+++ b/sound/soc/ti/davinci-mcasp.c
@@ -70,6 +70,7 @@ struct davinci_mcasp_context {
 struct davinci_mcasp_ruledata {
 	struct davinci_mcasp *mcasp;
 	int serializers;
+	u8 numevt;
 };
 
 struct davinci_mcasp {
@@ -1470,12 +1471,13 @@ static int davinci_mcasp_hw_rule_format(struct snd_pcm_hw_params *params,
 static int davinci_mcasp_hw_rule_min_periodsize(
 		struct snd_pcm_hw_params *params, struct snd_pcm_hw_rule *rule)
 {
+	struct davinci_mcasp_ruledata *rd = rule->private;
 	struct snd_interval *period_size = hw_param_interval(params,
 						SNDRV_PCM_HW_PARAM_PERIOD_SIZE);
 	struct snd_interval frames;
 
 	snd_interval_any(&frames);
-	frames.min = 64;
+	frames.min = rd->numevt;
 	frames.integer = 1;
 
 	return snd_interval_refine(period_size, &frames);
@@ -1516,6 +1518,9 @@ static int davinci_mcasp_startup(struct snd_pcm_substream *substream,
 		if (mcasp->serial_dir[i] == dir)
 			max_channels++;
 	}
+	ruledata->numevt = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) ?
+				   mcasp->txnumevt :
+				   mcasp->rxnumevt;
 	ruledata->serializers = max_channels;
 	ruledata->mcasp = mcasp;
 	max_channels *= tdm_slots;
@@ -1591,7 +1596,7 @@ static int davinci_mcasp_startup(struct snd_pcm_substream *substream,
 
 	snd_pcm_hw_rule_add(substream->runtime, 0,
 			    SNDRV_PCM_HW_PARAM_PERIOD_SIZE,
-			    davinci_mcasp_hw_rule_min_periodsize, NULL,
+			    davinci_mcasp_hw_rule_min_periodsize, ruledata,
 			    SNDRV_PCM_HW_PARAM_PERIOD_SIZE, -1);
 
 	return 0;

-- 
2.43.0

Re: [PATCH 2/2] ASoC: ti: davinci-mcasp: Set min period size using FIFO config

[Péter Ujfalusi]

Hi,

On 6/4/24 1:01 PM, Jai Luthra wrote:
> The minimum period size was enforced to 64 as older devices integrating
> McASP with EDMA used an internal FIFO of 64 samples.
> 
> With UDMA based platforms this internal McASP FIFO is optional, as the
> DMA engine internally does some buffering which is already accounted for
> when registering the platform. So we should read the actual FIFO
> configuration (txnumevt/rxnumevt) instead of hardcoding frames.min to
> 64.
> 
> Signed-off-by: Jai Luthra <j-luthra@ti.com>
> ---
>  sound/soc/ti/davinci-mcasp.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/sound/soc/ti/davinci-mcasp.c b/sound/soc/ti/davinci-mcasp.c
> index 1e760c315521..2a53fb7e72eb 100644
> --- a/sound/soc/ti/davinci-mcasp.c
> +++ b/sound/soc/ti/davinci-mcasp.c
> @@ -70,6 +70,7 @@ struct davinci_mcasp_context {
>  struct davinci_mcasp_ruledata {
>  	struct davinci_mcasp *mcasp;
>  	int serializers;
> +	u8 numevt;
>  };
>  
>  struct davinci_mcasp {
> @@ -1470,12 +1471,13 @@ static int davinci_mcasp_hw_rule_format(struct snd_pcm_hw_params *params,
>  static int davinci_mcasp_hw_rule_min_periodsize(
>  		struct snd_pcm_hw_params *params, struct snd_pcm_hw_rule *rule)
>  {
> +	struct davinci_mcasp_ruledata *rd = rule->private;
>  	struct snd_interval *period_size = hw_param_interval(params,
>  						SNDRV_PCM_HW_PARAM_PERIOD_SIZE);
>  	struct snd_interval frames;
>  
>  	snd_interval_any(&frames);
> -	frames.min = 64;
> +	frames.min = rd->numevt;

64 was a nice number ;)

>  	frames.integer = 1;
>  
>  	return snd_interval_refine(period_size, &frames);
> @@ -1516,6 +1518,9 @@ static int davinci_mcasp_startup(struct snd_pcm_substream *substream,
>  		if (mcasp->serial_dir[i] == dir)
>  			max_channels++;
>  	}
> +	ruledata->numevt = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) ?
> +				   mcasp->txnumevt :
> +				   mcasp->rxnumevt;

Do this at the same location where the rest of the ruledata members are
initialized, or

>  	ruledata->serializers = max_channels;
>  	ruledata->mcasp = mcasp;
>  	max_channels *= tdm_slots;
> @@ -1591,7 +1596,7 @@ static int davinci_mcasp_startup(struct snd_pcm_substream *substream,
>  
>  	snd_pcm_hw_rule_add(substream->runtime, 0,
>  			    SNDRV_PCM_HW_PARAM_PERIOD_SIZE,
> -			    davinci_mcasp_hw_rule_min_periodsize, NULL,
> +			    davinci_mcasp_hw_rule_min_periodsize, ruledata,

You could just pass a pointer to txnumevt/rxnumevt directly...

>  			    SNDRV_PCM_HW_PARAM_PERIOD_SIZE, -1);
>  
>  	return 0;
> 

-- 
Péter

Re: [PATCH 1/2] ALSA: dmaengine: Synchronize dma channel in prepare()

[Péter Ujfalusi]

On 6/4/24 1:01 PM, Jai Luthra wrote:
> Sometimes the stream may be stopped due to XRUN events, in which case
> the userspace can call snd_pcm_drop() and snd_pcm_prepare() to stop and
> start the stream again.
> 
> In these cases, we must wait for the DMA channel to synchronize before
> marking the stream as prepared for playback, as the DMA channel gets
> stopped by snd_pcm_drop() without any synchronization.

Right, this is a plausible scenario, the xrun is pointing to unhealthy
system, but before re-using the channel we indeed need to make sure that
it is finished with the stop.

Reviewed-by: Peter Ujfalusi <peter.ujfalusi@gmail.com>

> Signed-off-by: Jai Luthra <j-luthra@ti.com>
> ---
>  include/sound/dmaengine_pcm.h         |  1 +
>  sound/core/pcm_dmaengine.c            | 10 ++++++++++
>  sound/soc/soc-generic-dmaengine-pcm.c |  8 ++++++++
>  3 files changed, 19 insertions(+)
> 
> diff --git a/include/sound/dmaengine_pcm.h b/include/sound/dmaengine_pcm.h
> index c11aaf8079fb..9c5800e5659f 100644
> --- a/include/sound/dmaengine_pcm.h
> +++ b/include/sound/dmaengine_pcm.h
> @@ -36,6 +36,7 @@ snd_pcm_uframes_t snd_dmaengine_pcm_pointer_no_residue(struct snd_pcm_substream
>  int snd_dmaengine_pcm_open(struct snd_pcm_substream *substream,
>  	struct dma_chan *chan);
>  int snd_dmaengine_pcm_close(struct snd_pcm_substream *substream);
> +int snd_dmaengine_pcm_prepare(struct snd_pcm_substream *substream);
>  
>  int snd_dmaengine_pcm_open_request_chan(struct snd_pcm_substream *substream,
>  	dma_filter_fn filter_fn, void *filter_data);
> diff --git a/sound/core/pcm_dmaengine.c b/sound/core/pcm_dmaengine.c
> index 12aa1cef11a1..dbf5c6136d68 100644
> --- a/sound/core/pcm_dmaengine.c
> +++ b/sound/core/pcm_dmaengine.c
> @@ -349,6 +349,16 @@ int snd_dmaengine_pcm_open_request_chan(struct snd_pcm_substream *substream,
>  }
>  EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_open_request_chan);
>  
> +int snd_dmaengine_pcm_prepare(struct snd_pcm_substream *substream)
> +{
> +	struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);
> +
> +	dmaengine_synchronize(prtd->dma_chan);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_prepare);
> +
>  /**
>   * snd_dmaengine_pcm_close - Close a dmaengine based PCM substream
>   * @substream: PCM substream
> diff --git a/sound/soc/soc-generic-dmaengine-pcm.c b/sound/soc/soc-generic-dmaengine-pcm.c
> index ea3bc9318412..af439486d33a 100644
> --- a/sound/soc/soc-generic-dmaengine-pcm.c
> +++ b/sound/soc/soc-generic-dmaengine-pcm.c
> @@ -318,6 +318,12 @@ static int dmaengine_copy(struct snd_soc_component *component,
>  	return 0;
>  }
>  
> +int dmaengine_pcm_prepare(struct snd_soc_component *component,
> +			  struct snd_pcm_substream *substream)
> +{
> +	return snd_dmaengine_pcm_prepare(substream);
> +}
> +
>  static const struct snd_soc_component_driver dmaengine_pcm_component = {
>  	.name		= SND_DMAENGINE_PCM_DRV_NAME,
>  	.probe_order	= SND_SOC_COMP_ORDER_LATE,
> @@ -327,6 +333,7 @@ static const struct snd_soc_component_driver dmaengine_pcm_component = {
>  	.trigger	= dmaengine_pcm_trigger,
>  	.pointer	= dmaengine_pcm_pointer,
>  	.pcm_construct	= dmaengine_pcm_new,
> +	.prepare	= dmaengine_pcm_prepare,
>  };
>  
>  static const struct snd_soc_component_driver dmaengine_pcm_component_process = {
> @@ -339,6 +346,7 @@ static const struct snd_soc_component_driver dmaengine_pcm_component_process = {
>  	.pointer	= dmaengine_pcm_pointer,
>  	.copy		= dmaengine_copy,
>  	.pcm_construct	= dmaengine_pcm_new,
> +	.prepare	= dmaengine_pcm_prepare,
>  };
>  
>  static const char * const dmaengine_pcm_dma_channel_names[] = {
> 

-- 
Péter