ASoC: fsl_sai: Fix noise when using EDMA
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Message ID 20190830200900.19668-1-daniel.baluta@nxp.com
State New
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Series
  • ASoC: fsl_sai: Fix noise when using EDMA
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Commit Message

Daniel Baluta Aug. 30, 2019, 8:09 p.m. UTC
From: Mihai Serban <mihai.serban@nxp.com>

EDMA requires the period size to be multiple of maxburst. Otherwise the
remaining bytes are not transferred and thus noise is produced.

We can handle this issue by adding a constraint on
SNDRV_PCM_HW_PARAM_PERIOD_SIZE to be multiple of tx/rx maxburst value.

Cc: NXP Linux Team <linux-imx@nxp.com>
Signed-off-by: Mihai Serban <mihai.serban@nxp.com>
Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
---
 sound/soc/fsl/fsl_sai.c | 15 +++++++++++++++
 sound/soc/fsl/fsl_sai.h |  1 +
 2 files changed, 16 insertions(+)

Comments

Nicolin Chen Sept. 6, 2019, 1:24 a.m. UTC | #1
On Fri, Aug 30, 2019 at 11:09:00PM +0300, Daniel Baluta wrote:
> From: Mihai Serban <mihai.serban@nxp.com>
> 
> EDMA requires the period size to be multiple of maxburst. Otherwise the
> remaining bytes are not transferred and thus noise is produced.
> 
> We can handle this issue by adding a constraint on
> SNDRV_PCM_HW_PARAM_PERIOD_SIZE to be multiple of tx/rx maxburst value.
> 
> Cc: NXP Linux Team <linux-imx@nxp.com>
> Signed-off-by: Mihai Serban <mihai.serban@nxp.com>
> Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
> ---
>  sound/soc/fsl/fsl_sai.c | 15 +++++++++++++++
>  sound/soc/fsl/fsl_sai.h |  1 +
>  2 files changed, 16 insertions(+)
> 
> diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
> index 728307acab90..fe126029f4e3 100644
> --- a/sound/soc/fsl/fsl_sai.c
> +++ b/sound/soc/fsl/fsl_sai.c
> @@ -612,6 +612,16 @@ static int fsl_sai_startup(struct snd_pcm_substream *substream,
>  			   FSL_SAI_CR3_TRCE_MASK,
>  			   FSL_SAI_CR3_TRCE);
>  
> +	/*
> +	 * some DMA controllers need period size to be a multiple of
> +	 * tx/rx maxburst
> +	 */
> +	if (sai->soc_data->use_constraint_period_size)
> +		snd_pcm_hw_constraint_step(substream->runtime, 0,
> +					   SNDRV_PCM_HW_PARAM_PERIOD_SIZE,
> +					   tx ? sai->dma_params_tx.maxburst :
> +					   sai->dma_params_rx.maxburst);

I feel that PERIOD_SIZE could be used for some other cases than
being related to maxburst....
  
>  static const struct of_device_id fsl_sai_ids[] = {
> diff --git a/sound/soc/fsl/fsl_sai.h b/sound/soc/fsl/fsl_sai.h
> index b89b0ca26053..3a3f6f8e5595 100644
> --- a/sound/soc/fsl/fsl_sai.h
> +++ b/sound/soc/fsl/fsl_sai.h
> @@ -157,6 +157,7 @@
>  
>  struct fsl_sai_soc_data {
>  	bool use_imx_pcm;
> +	bool use_constraint_period_size;

....so maybe the soc specific flag here could be something like
	bool use_edma;

What do you think?
Daniel Baluta Sept. 6, 2019, 6:46 a.m. UTC | #2
On Fri, Sep 6, 2019 at 4:25 AM Nicolin Chen <nicoleotsuka@gmail.com> wrote:
>
> On Fri, Aug 30, 2019 at 11:09:00PM +0300, Daniel Baluta wrote:
> > From: Mihai Serban <mihai.serban@nxp.com>
> >
> > EDMA requires the period size to be multiple of maxburst. Otherwise the
> > remaining bytes are not transferred and thus noise is produced.
> >
> > We can handle this issue by adding a constraint on
> > SNDRV_PCM_HW_PARAM_PERIOD_SIZE to be multiple of tx/rx maxburst value.
> >
> > Cc: NXP Linux Team <linux-imx@nxp.com>
> > Signed-off-by: Mihai Serban <mihai.serban@nxp.com>
> > Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
> > ---
> >  sound/soc/fsl/fsl_sai.c | 15 +++++++++++++++
> >  sound/soc/fsl/fsl_sai.h |  1 +
> >  2 files changed, 16 insertions(+)
> >
> > diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
> > index 728307acab90..fe126029f4e3 100644
> > --- a/sound/soc/fsl/fsl_sai.c
> > +++ b/sound/soc/fsl/fsl_sai.c
> > @@ -612,6 +612,16 @@ static int fsl_sai_startup(struct snd_pcm_substream *substream,
> >                          FSL_SAI_CR3_TRCE_MASK,
> >                          FSL_SAI_CR3_TRCE);
> >
> > +     /*
> > +      * some DMA controllers need period size to be a multiple of
> > +      * tx/rx maxburst
> > +      */
> > +     if (sai->soc_data->use_constraint_period_size)
> > +             snd_pcm_hw_constraint_step(substream->runtime, 0,
> > +                                        SNDRV_PCM_HW_PARAM_PERIOD_SIZE,
> > +                                        tx ? sai->dma_params_tx.maxburst :
> > +                                        sai->dma_params_rx.maxburst);
>
> I feel that PERIOD_SIZE could be used for some other cases than
> being related to maxburst....
>
> >  static const struct of_device_id fsl_sai_ids[] = {
> > diff --git a/sound/soc/fsl/fsl_sai.h b/sound/soc/fsl/fsl_sai.h
> > index b89b0ca26053..3a3f6f8e5595 100644
> > --- a/sound/soc/fsl/fsl_sai.h
> > +++ b/sound/soc/fsl/fsl_sai.h
> > @@ -157,6 +157,7 @@
> >
> >  struct fsl_sai_soc_data {
> >       bool use_imx_pcm;
> > +     bool use_constraint_period_size;
>
> ....so maybe the soc specific flag here could be something like
>         bool use_edma;
>
> What do you think?

I think your suggestion is a little bit better than what we have. But what if
in the future another DMA controler (not eDMA) will need the same constraint.

Wouldn't it be confusing?
Nicolin Chen Sept. 9, 2019, 7:32 p.m. UTC | #3
On Fri, Sep 06, 2019 at 09:46:12AM +0300, Daniel Baluta wrote:
> On Fri, Sep 6, 2019 at 4:25 AM Nicolin Chen <nicoleotsuka@gmail.com> wrote:
> >
> > On Fri, Aug 30, 2019 at 11:09:00PM +0300, Daniel Baluta wrote:
> > > From: Mihai Serban <mihai.serban@nxp.com>
> > >
> > > EDMA requires the period size to be multiple of maxburst. Otherwise the
> > > remaining bytes are not transferred and thus noise is produced.
> > >
> > > We can handle this issue by adding a constraint on
> > > SNDRV_PCM_HW_PARAM_PERIOD_SIZE to be multiple of tx/rx maxburst value.
> > >
> > > Cc: NXP Linux Team <linux-imx@nxp.com>
> > > Signed-off-by: Mihai Serban <mihai.serban@nxp.com>
> > > Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
> > > ---
> > >  sound/soc/fsl/fsl_sai.c | 15 +++++++++++++++
> > >  sound/soc/fsl/fsl_sai.h |  1 +
> > >  2 files changed, 16 insertions(+)
> > >
> > > diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
> > > index 728307acab90..fe126029f4e3 100644
> > > --- a/sound/soc/fsl/fsl_sai.c
> > > +++ b/sound/soc/fsl/fsl_sai.c
> > > @@ -612,6 +612,16 @@ static int fsl_sai_startup(struct snd_pcm_substream *substream,
> > >                          FSL_SAI_CR3_TRCE_MASK,
> > >                          FSL_SAI_CR3_TRCE);
> > >
> > > +     /*
> > > +      * some DMA controllers need period size to be a multiple of
> > > +      * tx/rx maxburst
> > > +      */
> > > +     if (sai->soc_data->use_constraint_period_size)
> > > +             snd_pcm_hw_constraint_step(substream->runtime, 0,:
> > > +                                        SNDRV_PCM_HW_PARAM_PERIOD_SIZE,
> > > +                                        tx ? sai->dma_params_tx.maxburst :
> > > +                                        sai->dma_params_rx.maxburst);
> >
> > I feel that PERIOD_SIZE could be used for some other cases than
> > being related to maxburst....
> >
> > >  static const struct of_device_id fsl_sai_ids[] = {
> > > diff --git a/sound/soc/fsl/fsl_sai.h b/sound/soc/fsl/fsl_sai.h
> > > index b89b0ca26053..3a3f6f8e5595 100644
> > > --- a/sound/soc/fsl/fsl_sai.h
> > > +++ b/sound/soc/fsl/fsl_sai.h
> > > @@ -157,6 +157,7 @@
> > >
> > >  struct fsl_sai_soc_data {
> > >       bool use_imx_pcm;
> > > +     bool use_constraint_period_size;
> >
> > ....so maybe the soc specific flag here could be something like
> >         bool use_edma;
> >
> > What do you think?
> 
> I think your suggestion is a little bit better than what we have. But what if

The better part of using "edma" word, I felt, is to match this
"soc" word in the structure name.

> in the future another DMA controler (not eDMA) will need the same constraint.

That sounds like a valid point to me, I don't feel it'd happen
that often though. I'd be okay if you insist to keep yours :)

Patch
diff mbox series

diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
index 728307acab90..fe126029f4e3 100644
--- a/sound/soc/fsl/fsl_sai.c
+++ b/sound/soc/fsl/fsl_sai.c
@@ -612,6 +612,16 @@  static int fsl_sai_startup(struct snd_pcm_substream *substream,
 			   FSL_SAI_CR3_TRCE_MASK,
 			   FSL_SAI_CR3_TRCE);
 
+	/*
+	 * some DMA controllers need period size to be a multiple of
+	 * tx/rx maxburst
+	 */
+	if (sai->soc_data->use_constraint_period_size)
+		snd_pcm_hw_constraint_step(substream->runtime, 0,
+					   SNDRV_PCM_HW_PARAM_PERIOD_SIZE,
+					   tx ? sai->dma_params_tx.maxburst :
+					   sai->dma_params_rx.maxburst);
+
 	ret = snd_pcm_hw_constraint_list(substream->runtime, 0,
 			SNDRV_PCM_HW_PARAM_RATE, &fsl_sai_rate_constraints);
 
@@ -1011,30 +1021,35 @@  static const struct fsl_sai_soc_data fsl_sai_vf610_data = {
 	.use_imx_pcm = false,
 	.fifo_depth = 32,
 	.reg_offset = 0,
+	.use_constraint_period_size = false,
 };
 
 static const struct fsl_sai_soc_data fsl_sai_imx6sx_data = {
 	.use_imx_pcm = true,
 	.fifo_depth = 32,
 	.reg_offset = 0,
+	.use_constraint_period_size = false,
 };
 
 static const struct fsl_sai_soc_data fsl_sai_imx7ulp_data = {
 	.use_imx_pcm = true,
 	.fifo_depth = 16,
 	.reg_offset = 8,
+	.use_constraint_period_size = false,
 };
 
 static const struct fsl_sai_soc_data fsl_sai_imx8mq_data = {
 	.use_imx_pcm = true,
 	.fifo_depth = 128,
 	.reg_offset = 8,
+	.use_constraint_period_size = false,
 };
 
 static const struct fsl_sai_soc_data fsl_sai_imx8qm_data = {
 	.use_imx_pcm = true,
 	.fifo_depth = 64,
 	.reg_offset = 0,
+	.use_constraint_period_size = true,
 };
 
 static const struct of_device_id fsl_sai_ids[] = {
diff --git a/sound/soc/fsl/fsl_sai.h b/sound/soc/fsl/fsl_sai.h
index b89b0ca26053..3a3f6f8e5595 100644
--- a/sound/soc/fsl/fsl_sai.h
+++ b/sound/soc/fsl/fsl_sai.h
@@ -157,6 +157,7 @@ 
 
 struct fsl_sai_soc_data {
 	bool use_imx_pcm;
+	bool use_constraint_period_size;
 	unsigned int fifo_depth;
 	unsigned int reg_offset;
 };