Re: [alsa-devel][PATCH 1/3] SoC: fsl_sai: add sai master mode support

[Nicolin Chen]

On Wed, Jan 21, 2015 at 05:25:32PM +0800, Zidan Wang wrote:
> On Tue, Jan 20, 2015 at 10:07:03PM -0800, Nicolin Chen wrote:
> > On Tue, Jan 20, 2015 at 08:21:18PM +0800, Zidan Wang wrote:

> > > + if ((tx && sai->synchronous[TX]) || (!tx && !sai->synchronous[RX])) {
> > > + regmap_update_bits(sai->regmap, FSL_SAI_RCR2,
> > > + FSL_SAI_CR2_MSEL_MASK, FSL_SAI_CR2_MSEL(sai->mclk_id));

> > "tx && sai->synchronous[TX]" means the playback in synchronous
> > mode (TX following RX). What if the recording has been already
> > activated with an MSEL setting at this point? Then the playback
> > stream, as a secondary stream, will overwrite MSEL of the first
> > stream -- Record. Same would happen to the DIV configuration.
> > 
> When TX following RX(or RX following TX), TX and RX works on same bit
> clock and frame clock. They will use same MCLK source, and just need set
> the bclk DIV for RX(or TX). The secondary stream will overwrite MSEL and
> bclk DIV of the first stream, but it doesn't matter.
> 
> For RX(or TX) sync:
> fsl_sai_dai.symmetric_rates = 1;
> fsl_sai_dai.symmetric_channels = 1;
> fsl_sai_dai.symmetric_samplebits = 1;

Ah, I forgot we have protection here. It's fine then.

> When TX and RX both works on async mode, TX and RX may works on
> different bit clock and frame clock. We need set MCLK source and bclk
> DIV for TX and RX. mclk_id just save a MCLK source id, so i need to define
> mclk_id[2] for differnet stream.

Yes, you need to change this part as you just realized.

And one more thing for your coding style for multi-line comment:
/*
 * Typically use this format.
 */

Thanks
Nicolin
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Re: [alsa-devel][PATCH 1/3] SoC: fsl_sai: add sai master mode support

[Zidan Wang]

On Tue, Jan 20, 2015 at 10:07:03PM -0800, Nicolin Chen wrote:
> On Tue, Jan 20, 2015 at 08:21:18PM +0800, Zidan Wang wrote:
> > +static int fsl_sai_set_bclk(struct snd_soc_dai *dai, bool tx, u32 freq)
> 
> > +   if ((tx && sai->synchronous[TX]) || (!tx && !sai->synchronous[RX])) {
> > +   regmap_update_bits(sai->regmap, FSL_SAI_RCR2,
> > +   FSL_SAI_CR2_MSEL_MASK, FSL_SAI_CR2_MSEL(sai->mclk_id));
> > +   regmap_update_bits(sai->regmap, FSL_SAI_RCR2,
> > +   FSL_SAI_CR2_DIV_MASK, savediv - 1);
> 
> Hmm...the case should be a bit more complicated here IMO.
> 
> "tx && sai->synchronous[TX]" means the playback in synchronous
> mode (TX following RX). What if the recording has been already
> activated with an MSEL setting at this point? Then the playback
> stream, as a secondary stream, will overwrite MSEL of the first
> stream -- Record. Same would happen to the DIV configuration.
> 
When TX following RX(or RX following TX), TX and RX works on same bit
clock and frame clock. They will use same MCLK source, and just need set
the bclk DIV for RX(or TX). The secondary stream will overwrite MSEL and
bclk DIV of the first stream, but it doesn't matter.

For RX(or TX) sync:
fsl_sai_dai.symmetric_rates = 1;
fsl_sai_dai.symmetric_channels = 1;
fsl_sai_dai.symmetric_samplebits = 1;

When TX and RX both works on async mode, TX and RX may works on
different bit clock and frame clock. We need set MCLK source and bclk
DIV for TX and RX. mclk_id just save a MCLK source id, so i need to define
mclk_id[2] for differnet stream.

For TX and RX async:
fsl_sai_dai.symmetric_rates = 0;
fsl_sai_dai.symmetric_channels = 0;
fsl_sai_dai.symmetric_samplebits = 0;

> > @@ -297,6 +368,24 @@ static int fsl_sai_hw_params(struct snd_pcm_substream 
> > *substream,
> > unsigned int channels = params_channels(params);
> > u32 word_width = snd_pcm_format_width(params_format(params));
> > u32 val_cr4 = 0, val_cr5 = 0;
> > +   int ret;
> > +
> > +   if (!sai->is_slave_mode) {
> > +   ret = fsl_sai_set_bclk(cpu_dai, tx,
> > +   2 * word_width * params_rate(params));
> > +   if (ret)
> > +   return ret;
> > +
> > +   /* Do not enable the clock if it is already enabled */
> 
> It actually doesn't matter to enable the clock again since it
> purely increaes its count. But we do need a protection for MSEL
> overwritten issue resulted from the fsl_sai_set_bclk() call.
> 
> > @@ -133,10 +135,13 @@ struct fsl_sai {
> > struct clk *mclk_clk[FSL_SAI_MCLK_MAX];
> >  
> > bool is_lsb_first;
> > +   bool is_slave_mode;
> > bool is_dsp_mode;
> > bool sai_on_imx;
> > bool synchronous[2];
> >  
> > +   unsigned int mclk_id;
> > +   unsigned int mclk_streams;
> 
> Besides, I doubt that only one property of mclk_id can content
> Asynchronous Mode -- TX and RX can fetch their clocks from
> different MCLK sources.
> 
When hw_params failed before mclk enable, hw_free will also decrease 
the clk usecount. So add mclk_streams, when clk successful enabled, 
set corresponding bit of mclk_stream. And clear such bit after clk disabled.
> Nicolin
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Re: [alsa-devel][PATCH 1/3] SoC: fsl_sai: add sai master mode support

[Nicolin Chen]

On Wed, Jan 21, 2015 at 05:25:32PM +0800, Zidan Wang wrote:
 On Tue, Jan 20, 2015 at 10:07:03PM -0800, Nicolin Chen wrote:
  On Tue, Jan 20, 2015 at 08:21:18PM +0800, Zidan Wang wrote:

   + if ((tx  sai-synchronous[TX]) || (!tx  !sai-synchronous[RX])) {
   + regmap_update_bits(sai-regmap, FSL_SAI_RCR2,
   + FSL_SAI_CR2_MSEL_MASK, FSL_SAI_CR2_MSEL(sai-mclk_id));

  tx  sai-synchronous[TX] means the playback in synchronous
  mode (TX following RX). What if the recording has been already
  activated with an MSEL setting at this point? Then the playback
  stream, as a secondary stream, will overwrite MSEL of the first
  stream -- Record. Same would happen to the DIV configuration.
  
 When TX following RX(or RX following TX), TX and RX works on same bit
 clock and frame clock. They will use same MCLK source, and just need set
 the bclk DIV for RX(or TX). The secondary stream will overwrite MSEL and
 bclk DIV of the first stream, but it doesn't matter.
 
 For RX(or TX) sync:
 fsl_sai_dai.symmetric_rates = 1;
 fsl_sai_dai.symmetric_channels = 1;
 fsl_sai_dai.symmetric_samplebits = 1;

Ah, I forgot we have protection here. It's fine then.

 When TX and RX both works on async mode, TX and RX may works on
 different bit clock and frame clock. We need set MCLK source and bclk
 DIV for TX and RX. mclk_id just save a MCLK source id, so i need to define
 mclk_id[2] for differnet stream.

Yes, you need to change this part as you just realized.

And one more thing for your coding style for multi-line comment:
/*
 * Typically use this format.
 */

Thanks
Nicolin
--
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Re: [alsa-devel][PATCH 1/3] SoC: fsl_sai: add sai master mode support

[Zidan Wang]

On Tue, Jan 20, 2015 at 10:07:03PM -0800, Nicolin Chen wrote:
 On Tue, Jan 20, 2015 at 08:21:18PM +0800, Zidan Wang wrote:
  +static int fsl_sai_set_bclk(struct snd_soc_dai *dai, bool tx, u32 freq)
 
  +   if ((tx  sai-synchronous[TX]) || (!tx  !sai-synchronous[RX])) {
  +   regmap_update_bits(sai-regmap, FSL_SAI_RCR2,
  +   FSL_SAI_CR2_MSEL_MASK, FSL_SAI_CR2_MSEL(sai-mclk_id));
  +   regmap_update_bits(sai-regmap, FSL_SAI_RCR2,
  +   FSL_SAI_CR2_DIV_MASK, savediv - 1);
 
 Hmm...the case should be a bit more complicated here IMO.
 
 tx  sai-synchronous[TX] means the playback in synchronous
 mode (TX following RX). What if the recording has been already
 activated with an MSEL setting at this point? Then the playback
 stream, as a secondary stream, will overwrite MSEL of the first
 stream -- Record. Same would happen to the DIV configuration.
 
When TX following RX(or RX following TX), TX and RX works on same bit
clock and frame clock. They will use same MCLK source, and just need set
the bclk DIV for RX(or TX). The secondary stream will overwrite MSEL and
bclk DIV of the first stream, but it doesn't matter.

For RX(or TX) sync:
fsl_sai_dai.symmetric_rates = 1;
fsl_sai_dai.symmetric_channels = 1;
fsl_sai_dai.symmetric_samplebits = 1;

When TX and RX both works on async mode, TX and RX may works on
different bit clock and frame clock. We need set MCLK source and bclk
DIV for TX and RX. mclk_id just save a MCLK source id, so i need to define
mclk_id[2] for differnet stream.

For TX and RX async:
fsl_sai_dai.symmetric_rates = 0;
fsl_sai_dai.symmetric_channels = 0;
fsl_sai_dai.symmetric_samplebits = 0;

  @@ -297,6 +368,24 @@ static int fsl_sai_hw_params(struct snd_pcm_substream 
  *substream,
  unsigned int channels = params_channels(params);
  u32 word_width = snd_pcm_format_width(params_format(params));
  u32 val_cr4 = 0, val_cr5 = 0;
  +   int ret;
  +
  +   if (!sai-is_slave_mode) {
  +   ret = fsl_sai_set_bclk(cpu_dai, tx,
  +   2 * word_width * params_rate(params));
  +   if (ret)
  +   return ret;
  +
  +   /* Do not enable the clock if it is already enabled */
 
 It actually doesn't matter to enable the clock again since it
 purely increaes its count. But we do need a protection for MSEL
 overwritten issue resulted from the fsl_sai_set_bclk() call.
 
  @@ -133,10 +135,13 @@ struct fsl_sai {
  struct clk *mclk_clk[FSL_SAI_MCLK_MAX];
   
  bool is_lsb_first;
  +   bool is_slave_mode;
  bool is_dsp_mode;
  bool sai_on_imx;
  bool synchronous[2];
   
  +   unsigned int mclk_id;
  +   unsigned int mclk_streams;
 
 Besides, I doubt that only one property of mclk_id can content
 Asynchronous Mode -- TX and RX can fetch their clocks from
 different MCLK sources.
 
When hw_params failed before mclk enable, hw_free will also decrease 
the clk usecount. So add mclk_streams, when clk successful enabled, 
set corresponding bit of mclk_stream. And clear such bit after clk disabled.
 Nicolin
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Re: [alsa-devel][PATCH 1/3] SoC: fsl_sai: add sai master mode support

[Nicolin Chen]

On Tue, Jan 20, 2015 at 08:21:18PM +0800, Zidan Wang wrote:
> +static int fsl_sai_set_bclk(struct snd_soc_dai *dai, bool tx, u32 freq)

> + if ((tx && sai->synchronous[TX]) || (!tx && !sai->synchronous[RX])) {
> + regmap_update_bits(sai->regmap, FSL_SAI_RCR2,
> + FSL_SAI_CR2_MSEL_MASK, FSL_SAI_CR2_MSEL(sai->mclk_id));
> + regmap_update_bits(sai->regmap, FSL_SAI_RCR2,
> + FSL_SAI_CR2_DIV_MASK, savediv - 1);

Hmm...the case should be a bit more complicated here IMO.

"tx && sai->synchronous[TX]" means the playback in synchronous
mode (TX following RX). What if the recording has been already
activated with an MSEL setting at this point? Then the playback
stream, as a secondary stream, will overwrite MSEL of the first
stream -- Record. Same would happen to the DIV configuration.

> @@ -297,6 +368,24 @@ static int fsl_sai_hw_params(struct snd_pcm_substream 
> *substream,
>   unsigned int channels = params_channels(params);
>   u32 word_width = snd_pcm_format_width(params_format(params));
>   u32 val_cr4 = 0, val_cr5 = 0;
> + int ret;
> +
> + if (!sai->is_slave_mode) {
> + ret = fsl_sai_set_bclk(cpu_dai, tx,
> + 2 * word_width * params_rate(params));
> + if (ret)
> + return ret;
> +
> + /* Do not enable the clock if it is already enabled */

It actually doesn't matter to enable the clock again since it
purely increaes its count. But we do need a protection for MSEL
overwritten issue resulted from the fsl_sai_set_bclk() call.

> @@ -133,10 +135,13 @@ struct fsl_sai {
>   struct clk *mclk_clk[FSL_SAI_MCLK_MAX];
>  
>   bool is_lsb_first;
> + bool is_slave_mode;
>   bool is_dsp_mode;
>   bool sai_on_imx;
>   bool synchronous[2];
>  
> + unsigned int mclk_id;
> + unsigned int mclk_streams;

Besides, I doubt that only one property of mclk_id can content
Asynchronous Mode -- TX and RX can fetch their clocks from
different MCLK sources.

Nicolin
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[alsa-devel][PATCH 1/3] SoC: fsl_sai: add sai master mode support

[Zidan Wang]

When sai works on master mode, set its bit clock and frame clock.

SAI has 4 MCLK source, bus clock, MCLK1, MCLK2 and MCLK3. fsl_sai_set_bclk
will select proper MCLK source, then calculate and set the bit clock divider.

After fsl_sai_set_bclk, enable the selected mclk in hw_params(), and add
hw_free() to disable the mclk.

Signed-off-by: Zidan Wang 
---
 sound/soc/fsl/fsl_sai.c | 110 +++-
 sound/soc/fsl/fsl_sai.h |   9 +++-
 2 files changed, 115 insertions(+), 4 deletions(-)

diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
index ec79c3d..499cbd9 100644
--- a/sound/soc/fsl/fsl_sai.c
+++ b/sound/soc/fsl/fsl_sai.c
@@ -251,12 +251,14 @@ static int fsl_sai_set_dai_fmt_tr(struct snd_soc_dai 
*cpu_dai,
val_cr4 |= FSL_SAI_CR4_FSD_MSTR;
break;
case SND_SOC_DAIFMT_CBM_CFM:
+   sai->is_slave_mode = true;
break;
case SND_SOC_DAIFMT_CBS_CFM:
val_cr2 |= FSL_SAI_CR2_BCD_MSTR;
break;
case SND_SOC_DAIFMT_CBM_CFS:
val_cr4 |= FSL_SAI_CR4_FSD_MSTR;
+   sai->is_slave_mode = true;
break;
default:
return -EINVAL;
@@ -288,6 +290,75 @@ static int fsl_sai_set_dai_fmt(struct snd_soc_dai 
*cpu_dai, unsigned int fmt)
return ret;
 }
 
+static int fsl_sai_set_bclk(struct snd_soc_dai *dai, bool tx, u32 freq)
+{
+   struct fsl_sai *sai = snd_soc_dai_get_drvdata(dai);
+   unsigned long clk_rate;
+   u32 savediv = 0, ratio, savesub = freq;
+   u32 id;
+   int ret = 0;
+
+   /* Don't apply to slave mode */
+   if (sai->is_slave_mode)
+   return 0;
+
+   for (id = 0; id < FSL_SAI_MCLK_MAX; id++) {
+   clk_rate = clk_get_rate(sai->mclk_clk[id]);
+   if (!clk_rate)
+   continue;
+
+   ratio = clk_rate / freq;
+
+   ret = clk_rate - ratio * freq;
+
+   /* Drop the source that can not be divided
+* into the required rate
+* */
+   if (ret != 0 && clk_rate / ret < 1000)
+   continue;
+
+   dev_dbg(dai->dev, "ratio %d for freq %dHz based on clock 
%ldHz\n",
+   ratio, freq, clk_rate);
+
+   if (ratio % 2 == 0 && ratio >= 2 && ratio <= 512)
+   ratio /= 2;
+   else
+   continue;
+
+   if (ret < savesub) {
+   savediv = ratio;
+   sai->mclk_id = id;
+   savesub = ret;
+   }
+
+   if (ret == 0)
+   break;
+   }
+
+   if (savediv == 0) {
+   dev_err(dai->dev, "failed to derive required %cx rate: %d\n",
+   tx ? 'T' : 'R', freq);
+   return -EINVAL;
+   }
+
+   if ((tx && sai->synchronous[TX]) || (!tx && !sai->synchronous[RX])) {
+   regmap_update_bits(sai->regmap, FSL_SAI_RCR2,
+   FSL_SAI_CR2_MSEL_MASK, FSL_SAI_CR2_MSEL(sai->mclk_id));
+   regmap_update_bits(sai->regmap, FSL_SAI_RCR2,
+   FSL_SAI_CR2_DIV_MASK, savediv - 1);
+   } else {
+   regmap_update_bits(sai->regmap, FSL_SAI_TCR2,
+   FSL_SAI_CR2_MSEL_MASK, FSL_SAI_CR2_MSEL(sai->mclk_id));
+   regmap_update_bits(sai->regmap, FSL_SAI_TCR2,
+   FSL_SAI_CR2_DIV_MASK, savediv - 1);
+   }
+
+   dev_dbg(dai->dev, "best fit: clock id=%d, div=%d, deviation =%d\n",
+   sai->mclk_id, savediv, savesub);
+
+   return 0;
+}
+
 static int fsl_sai_hw_params(struct snd_pcm_substream *substream,
struct snd_pcm_hw_params *params,
struct snd_soc_dai *cpu_dai)
@@ -297,6 +368,24 @@ static int fsl_sai_hw_params(struct snd_pcm_substream 
*substream,
unsigned int channels = params_channels(params);
u32 word_width = snd_pcm_format_width(params_format(params));
u32 val_cr4 = 0, val_cr5 = 0;
+   int ret;
+
+   if (!sai->is_slave_mode) {
+   ret = fsl_sai_set_bclk(cpu_dai, tx,
+   2 * word_width * params_rate(params));
+   if (ret)
+   return ret;
+
+   /* Do not enable the clock if it is already enabled */
+   if (!(sai->mclk_streams & BIT(substream->stream))) {
+   ret = clk_prepare_enable(sai->mclk_clk[sai->mclk_id]);
+   if (ret)
+   return ret;
+
+   sai->mclk_streams |= BIT(substream->stream);
+   }
+
+   }
 
if (!sai->is_dsp_mode)
val_cr4 |= FSL_SAI_CR4_SYWD(word_width);
@@ -322,6 +411,21 @@ static int fsl_sai_hw_params(struct snd_pcm_substream 
*substream,

[alsa-devel][PATCH 1/3] SoC: fsl_sai: add sai master mode support

[Zidan Wang]

When sai works on master mode, set its bit clock and frame clock.

SAI has 4 MCLK source, bus clock, MCLK1, MCLK2 and MCLK3. fsl_sai_set_bclk
will select proper MCLK source, then calculate and set the bit clock divider.

After fsl_sai_set_bclk, enable the selected mclk in hw_params(), and add
hw_free() to disable the mclk.

Signed-off-by: Zidan Wang zidan.w...@freescale.com
---
 sound/soc/fsl/fsl_sai.c | 110 +++-
 sound/soc/fsl/fsl_sai.h |   9 +++-
 2 files changed, 115 insertions(+), 4 deletions(-)

diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
index ec79c3d..499cbd9 100644
--- a/sound/soc/fsl/fsl_sai.c
+++ b/sound/soc/fsl/fsl_sai.c
@@ -251,12 +251,14 @@ static int fsl_sai_set_dai_fmt_tr(struct snd_soc_dai 
*cpu_dai,
val_cr4 |= FSL_SAI_CR4_FSD_MSTR;
break;
case SND_SOC_DAIFMT_CBM_CFM:
+   sai-is_slave_mode = true;
break;
case SND_SOC_DAIFMT_CBS_CFM:
val_cr2 |= FSL_SAI_CR2_BCD_MSTR;
break;
case SND_SOC_DAIFMT_CBM_CFS:
val_cr4 |= FSL_SAI_CR4_FSD_MSTR;
+   sai-is_slave_mode = true;
break;
default:
return -EINVAL;
@@ -288,6 +290,75 @@ static int fsl_sai_set_dai_fmt(struct snd_soc_dai 
*cpu_dai, unsigned int fmt)
return ret;
 }
 
+static int fsl_sai_set_bclk(struct snd_soc_dai *dai, bool tx, u32 freq)
+{
+   struct fsl_sai *sai = snd_soc_dai_get_drvdata(dai);
+   unsigned long clk_rate;
+   u32 savediv = 0, ratio, savesub = freq;
+   u32 id;
+   int ret = 0;
+
+   /* Don't apply to slave mode */
+   if (sai-is_slave_mode)
+   return 0;
+
+   for (id = 0; id  FSL_SAI_MCLK_MAX; id++) {
+   clk_rate = clk_get_rate(sai-mclk_clk[id]);
+   if (!clk_rate)
+   continue;
+
+   ratio = clk_rate / freq;
+
+   ret = clk_rate - ratio * freq;
+
+   /* Drop the source that can not be divided
+* into the required rate
+* */
+   if (ret != 0  clk_rate / ret  1000)
+   continue;
+
+   dev_dbg(dai-dev, ratio %d for freq %dHz based on clock 
%ldHz\n,
+   ratio, freq, clk_rate);
+
+   if (ratio % 2 == 0  ratio = 2  ratio = 512)
+   ratio /= 2;
+   else
+   continue;
+
+   if (ret  savesub) {
+   savediv = ratio;
+   sai-mclk_id = id;
+   savesub = ret;
+   }
+
+   if (ret == 0)
+   break;
+   }
+
+   if (savediv == 0) {
+   dev_err(dai-dev, failed to derive required %cx rate: %d\n,
+   tx ? 'T' : 'R', freq);
+   return -EINVAL;
+   }
+
+   if ((tx  sai-synchronous[TX]) || (!tx  !sai-synchronous[RX])) {
+   regmap_update_bits(sai-regmap, FSL_SAI_RCR2,
+   FSL_SAI_CR2_MSEL_MASK, FSL_SAI_CR2_MSEL(sai-mclk_id));
+   regmap_update_bits(sai-regmap, FSL_SAI_RCR2,
+   FSL_SAI_CR2_DIV_MASK, savediv - 1);
+   } else {
+   regmap_update_bits(sai-regmap, FSL_SAI_TCR2,
+   FSL_SAI_CR2_MSEL_MASK, FSL_SAI_CR2_MSEL(sai-mclk_id));
+   regmap_update_bits(sai-regmap, FSL_SAI_TCR2,
+   FSL_SAI_CR2_DIV_MASK, savediv - 1);
+   }
+
+   dev_dbg(dai-dev, best fit: clock id=%d, div=%d, deviation =%d\n,
+   sai-mclk_id, savediv, savesub);
+
+   return 0;
+}
+
 static int fsl_sai_hw_params(struct snd_pcm_substream *substream,
struct snd_pcm_hw_params *params,
struct snd_soc_dai *cpu_dai)
@@ -297,6 +368,24 @@ static int fsl_sai_hw_params(struct snd_pcm_substream 
*substream,
unsigned int channels = params_channels(params);
u32 word_width = snd_pcm_format_width(params_format(params));
u32 val_cr4 = 0, val_cr5 = 0;
+   int ret;
+
+   if (!sai-is_slave_mode) {
+   ret = fsl_sai_set_bclk(cpu_dai, tx,
+   2 * word_width * params_rate(params));
+   if (ret)
+   return ret;
+
+   /* Do not enable the clock if it is already enabled */
+   if (!(sai-mclk_streams  BIT(substream-stream))) {
+   ret = clk_prepare_enable(sai-mclk_clk[sai-mclk_id]);
+   if (ret)
+   return ret;
+
+   sai-mclk_streams |= BIT(substream-stream);
+   }
+
+   }
 
if (!sai-is_dsp_mode)
val_cr4 |= FSL_SAI_CR4_SYWD(word_width);
@@ -322,6 +411,21 @@ static int fsl_sai_hw_params(struct snd_pcm_substream 
*substream,
return 0;
 }
 
+static 

Re: [alsa-devel][PATCH 1/3] SoC: fsl_sai: add sai master mode support

[Nicolin Chen]

On Tue, Jan 20, 2015 at 08:21:18PM +0800, Zidan Wang wrote:
 +static int fsl_sai_set_bclk(struct snd_soc_dai *dai, bool tx, u32 freq)

 + if ((tx  sai-synchronous[TX]) || (!tx  !sai-synchronous[RX])) {
 + regmap_update_bits(sai-regmap, FSL_SAI_RCR2,
 + FSL_SAI_CR2_MSEL_MASK, FSL_SAI_CR2_MSEL(sai-mclk_id));
 + regmap_update_bits(sai-regmap, FSL_SAI_RCR2,
 + FSL_SAI_CR2_DIV_MASK, savediv - 1);

Hmm...the case should be a bit more complicated here IMO.

tx  sai-synchronous[TX] means the playback in synchronous
mode (TX following RX). What if the recording has been already
activated with an MSEL setting at this point? Then the playback
stream, as a secondary stream, will overwrite MSEL of the first
stream -- Record. Same would happen to the DIV configuration.

 @@ -297,6 +368,24 @@ static int fsl_sai_hw_params(struct snd_pcm_substream 
 *substream,
   unsigned int channels = params_channels(params);
   u32 word_width = snd_pcm_format_width(params_format(params));
   u32 val_cr4 = 0, val_cr5 = 0;
 + int ret;
 +
 + if (!sai-is_slave_mode) {
 + ret = fsl_sai_set_bclk(cpu_dai, tx,
 + 2 * word_width * params_rate(params));
 + if (ret)
 + return ret;
 +
 + /* Do not enable the clock if it is already enabled */

It actually doesn't matter to enable the clock again since it
purely increaes its count. But we do need a protection for MSEL
overwritten issue resulted from the fsl_sai_set_bclk() call.

 @@ -133,10 +135,13 @@ struct fsl_sai {
   struct clk *mclk_clk[FSL_SAI_MCLK_MAX];
  
   bool is_lsb_first;
 + bool is_slave_mode;
   bool is_dsp_mode;
   bool sai_on_imx;
   bool synchronous[2];
  
 + unsigned int mclk_id;
 + unsigned int mclk_streams;

Besides, I doubt that only one property of mclk_id can content
Asynchronous Mode -- TX and RX can fetch their clocks from
different MCLK sources.

Nicolin
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