Discussion:
[PATCH] ASoC: atmel_ssc_dai: Track playback and capture CMR dividers separately.
Peter Rosin
2014-10-20 13:45:23 UTC
Permalink
From 1e5621d7b9887c648d1a66238dc82d715c1e2cad Mon Sep 17 00:00:00 2001
From: Peter Rosin <***@axentia.se>
Date: Mon, 20 Oct 2014 14:38:04 +0200
Subject: [PATCH] ASoC: atmel_ssc_dai: Track playback and capture CMR dividers
separately.

The CMR divider register is shared by playback and capture. The SSC driver
therefore tries to enforce rules so that the needed register content do
not conflict during simultaneous playback/capture. However, the
implementation also prevents changing the register content in a
half-duplex scenario, which is needed when changing sample rates.

Thus, keep track of the desired playback and capture clock dividers
separately, and allow changing rates without closing the stream.

Signed-off-by: Peter Rosin <***@axentia.se>
---
sound/soc/atmel/atmel_ssc_dai.c | 31 ++++++++++++++++++++++---------
sound/soc/atmel/atmel_ssc_dai.h | 10 ++++++----
2 files changed, 28 insertions(+), 13 deletions(-)

diff --git a/sound/soc/atmel/atmel_ssc_dai.c b/sound/soc/atmel/atmel_ssc_dai.c
index f403f39..fec14fb 100644
--- a/sound/soc/atmel/atmel_ssc_dai.c
+++ b/sound/soc/atmel/atmel_ssc_dai.c
@@ -277,7 +277,8 @@ static void atmel_ssc_shutdown(struct snd_pcm_substream *substream,
/* Reset the SSC */
ssc_writel(ssc_p->ssc->regs, CR, SSC_BIT(CR_SWRST));
/* Clear the SSC dividers */
- ssc_p->cmr_div = ssc_p->tcmr_period = ssc_p->rcmr_period = 0;
+ ssc_p->tcmr_div = ssc_p->rcmr_div = 0;
+ ssc_p->tcmr_period = ssc_p->rcmr_period = 0;
}
spin_unlock_irq(&ssc_p->lock);
}
@@ -304,17 +305,27 @@ static int atmel_ssc_set_dai_clkdiv(struct snd_soc_dai *cpu_dai,
struct atmel_ssc_info *ssc_p = &ssc_info[cpu_dai->id];

switch (div_id) {
- case ATMEL_SSC_CMR_DIV:
+ case ATMEL_SSC_TCMR_DIV:
/*
* The same master clock divider is used for both
* transmit and receive, so if a value has already
- * been set, it must match this value.
+ * been set for the other direction, it must match
+ * this value.
*/
- if (ssc_p->cmr_div == 0)
- ssc_p->cmr_div = div;
- else
- if (div != ssc_p->cmr_div)
- return -EBUSY;
+ if (ssc_p->rcmr_div == 0)
+ ssc_p->tcmr_div = div;
+ else if (div != ssc_p->rcmr_div)
+ return -EBUSY;
+ break;
+
+ case ATMEL_SSC_RCMR_DIV:
+ /*
+ * See ATMEL_SSC_TCMR_DIV.
+ */
+ if (ssc_p->tcmr_div == 0)
+ ssc_p->rcmr_div = div;
+ else if (div != ssc_p->tcmr_div)
+ return -EBUSY;
break;

case ATMEL_SSC_TCMR_PERIOD:
@@ -345,6 +356,7 @@ static int atmel_ssc_hw_params(struct snd_pcm_substream *substream,
struct atmel_pcm_dma_params *dma_params;
int dir, channels, bits;
u32 tfmr, rfmr, tcmr, rcmr;
+ u16 cmr;
int start_event;
int ret;
int fslen, fslen_ext;
@@ -626,7 +638,8 @@ static int atmel_ssc_hw_params(struct snd_pcm_substream *substream,
}

/* set SSC clock mode register */
- ssc_writel(ssc_p->ssc->regs, CMR, ssc_p->cmr_div);
+ cmr = ssc_p->tcmr_div ? ssc_p->tcmr_div : ssc_p->rcmr_div;
+ ssc_writel(ssc_p->ssc->regs, CMR, cmr);

/* set receive clock mode and format */
ssc_writel(ssc_p->ssc->regs, RCMR, rcmr);
diff --git a/sound/soc/atmel/atmel_ssc_dai.h b/sound/soc/atmel/atmel_ssc_dai.h
index b1f08d5..a25df7a 100644
--- a/sound/soc/atmel/atmel_ssc_dai.h
+++ b/sound/soc/atmel/atmel_ssc_dai.h
@@ -39,9 +39,10 @@
#define ATMEL_SYSCLK_MCK 0 /* SSC uses AT91 MCK as system clock */

/* SSC divider ids */
-#define ATMEL_SSC_CMR_DIV 0 /* MCK divider for BCLK */
-#define ATMEL_SSC_TCMR_PERIOD 1 /* BCLK divider for transmit FS */
-#define ATMEL_SSC_RCMR_PERIOD 2 /* BCLK divider for receive FS */
+#define ATMEL_SSC_TCMR_DIV 0 /* MCK divider for transmit BCLK */
+#define ATMEL_SSC_RCMR_DIV 1 /* MCK divider for receive BCLK */
+#define ATMEL_SSC_TCMR_PERIOD 2 /* BCLK divider for transmit FS */
+#define ATMEL_SSC_RCMR_PERIOD 3 /* BCLK divider for receive FS */
/*
* SSC direction masks
*/
@@ -110,7 +111,8 @@ struct atmel_ssc_info {
unsigned short dir_mask; /* 0=unused, 1=playback, 2=capture */
unsigned short initialized; /* true if SSC has been initialized */
unsigned short daifmt;
- unsigned short cmr_div;
+ unsigned short tcmr_div;
+ unsigned short rcmr_div;
unsigned short tcmr_period;
unsigned short rcmr_period;
struct atmel_pcm_dma_params *dma_params[2];
--
1.7.10.4
Bo Shen
2014-10-21 01:54:07 UTC
Permalink
Hi Peter,
From 1e5621d7b9887c648d1a66238dc82d715c1e2cad Mon Sep 17 00:00:00 2001
Date: Mon, 20 Oct 2014 14:38:04 +0200
Subject: [PATCH] ASoC: atmel_ssc_dai: Track playback and capture CMR dividers
separately.
The CMR divider register is shared by playback and capture. The SSC driver
therefore tries to enforce rules so that the needed register content do
not conflict during simultaneous playback/capture. However, the
implementation also prevents changing the register content in a
half-duplex scenario, which is needed when changing sample rates.
I am not fully get what you mean here, do you mean:
- when playback, first playback 48kHz, and then playback 8Khz, the
8Khz still playback in 48kHz mode?

or other things?
Thus, keep track of the desired playback and capture clock dividers
separately, and allow changing rates without closing the stream.
---
sound/soc/atmel/atmel_ssc_dai.c | 31 ++++++++++++++++++++++---------
sound/soc/atmel/atmel_ssc_dai.h | 10 ++++++----
2 files changed, 28 insertions(+), 13 deletions(-)
diff --git a/sound/soc/atmel/atmel_ssc_dai.c b/sound/soc/atmel/atmel_ssc_dai.c
index f403f39..fec14fb 100644
--- a/sound/soc/atmel/atmel_ssc_dai.c
+++ b/sound/soc/atmel/atmel_ssc_dai.c
@@ -277,7 +277,8 @@ static void atmel_ssc_shutdown(struct snd_pcm_substream *substream,
/* Reset the SSC */
ssc_writel(ssc_p->ssc->regs, CR, SSC_BIT(CR_SWRST));
/* Clear the SSC dividers */
- ssc_p->cmr_div = ssc_p->tcmr_period = ssc_p->rcmr_period = 0;
+ ssc_p->tcmr_div = ssc_p->rcmr_div = 0;
+ ssc_p->tcmr_period = ssc_p->rcmr_period = 0;
}
spin_unlock_irq(&ssc_p->lock);
}
@@ -304,17 +305,27 @@ static int atmel_ssc_set_dai_clkdiv(struct snd_soc_dai *cpu_dai,
struct atmel_ssc_info *ssc_p = &ssc_info[cpu_dai->id];
switch (div_id) {
/*
* The same master clock divider is used for both
* transmit and receive, so if a value has already
- * been set, it must match this value.
+ * been set for the other direction, it must match
+ * this value.
*/
- if (ssc_p->cmr_div == 0)
- ssc_p->cmr_div = div;
- else
- if (div != ssc_p->cmr_div)
- return -EBUSY;
+ if (ssc_p->rcmr_div == 0)
+ ssc_p->tcmr_div = div;
+ else if (div != ssc_p->rcmr_div)
+ return -EBUSY;
+ break;
+
+ /*
+ * See ATMEL_SSC_TCMR_DIV.
+ */
+ if (ssc_p->tcmr_div == 0)
+ ssc_p->rcmr_div = div;
+ else if (div != ssc_p->tcmr_div)
+ return -EBUSY;
break;
@@ -345,6 +356,7 @@ static int atmel_ssc_hw_params(struct snd_pcm_substream *substream,
struct atmel_pcm_dma_params *dma_params;
int dir, channels, bits;
u32 tfmr, rfmr, tcmr, rcmr;
+ u16 cmr;
should be u32.
int start_event;
int ret;
int fslen, fslen_ext;
@@ -626,7 +638,8 @@ static int atmel_ssc_hw_params(struct snd_pcm_substream *substream,
}
/* set SSC clock mode register */
- ssc_writel(ssc_p->ssc->regs, CMR, ssc_p->cmr_div);
+ cmr = ssc_p->tcmr_div ? ssc_p->tcmr_div : ssc_p->rcmr_div;
+ ssc_writel(ssc_p->ssc->regs, CMR, cmr);
/* set receive clock mode and format */
ssc_writel(ssc_p->ssc->regs, RCMR, rcmr);
diff --git a/sound/soc/atmel/atmel_ssc_dai.h b/sound/soc/atmel/atmel_ssc_dai.h
index b1f08d5..a25df7a 100644
--- a/sound/soc/atmel/atmel_ssc_dai.h
+++ b/sound/soc/atmel/atmel_ssc_dai.h
@@ -39,9 +39,10 @@
#define ATMEL_SYSCLK_MCK 0 /* SSC uses AT91 MCK as system clock */
/* SSC divider ids */
-#define ATMEL_SSC_CMR_DIV 0 /* MCK divider for BCLK */
-#define ATMEL_SSC_TCMR_PERIOD 1 /* BCLK divider for transmit FS */
-#define ATMEL_SSC_RCMR_PERIOD 2 /* BCLK divider for receive FS */
+#define ATMEL_SSC_TCMR_DIV 0 /* MCK divider for transmit BCLK */
+#define ATMEL_SSC_RCMR_DIV 1 /* MCK divider for receive BCLK */
+#define ATMEL_SSC_TCMR_PERIOD 2 /* BCLK divider for transmit FS */
+#define ATMEL_SSC_RCMR_PERIOD 3 /* BCLK divider for receive FS */
/*
* SSC direction masks
*/
@@ -110,7 +111,8 @@ struct atmel_ssc_info {
unsigned short dir_mask; /* 0=unused, 1=playback, 2=capture */
unsigned short initialized; /* true if SSC has been initialized */
unsigned short daifmt;
- unsigned short cmr_div;
+ unsigned short tcmr_div;
+ unsigned short rcmr_div;
unsigned short tcmr_period;
unsigned short rcmr_period;
struct atmel_pcm_dma_params *dma_params[2];
Best Regards,
Bo Shen
Peter Rosin
2014-10-21 07:55:28 UTC
Permalink
Hi!

(and thank you for the pointer to the example with the ssc-dai in master mode)
Post by Bo Shen
Hi Peter,
From 1e5621d7b9887c648d1a66238dc82d715c1e2cad Mon Sep 17 00:00:00 2001
Date: Mon, 20 Oct 2014 14:38:04 +0200
Subject: [PATCH] ASoC: atmel_ssc_dai: Track playback and capture CMR
dividers
separately.
The CMR divider register is shared by playback and capture. The SSC
driver therefore tries to enforce rules so that the needed register
content do not conflict during simultaneous playback/capture. However,
the implementation also prevents changing the register content in a
half-duplex scenario, which is needed when changing sample rates.
- when playback, first playback 48kHz, and then playback 8Khz, the 8Khz still
playback in 48kHz mode?
or other things?
I do not know exactly why the problem occurs, but it might be connected to
the library (proprietary) we are using. It apparently uses the OSS interface
and somehow it opens a stream and changes the playback sample-rate a
couple of time before it settles on something. I don't know why this is
done, and I have no control over it. The end result is that without this patch,
the ssc-dai driver returns -EBUSY when the library changes the playback
sample-rate (the driver returns -EBUSY because it thinks that the new
sample rate does not match a previously given capture sample-rate, but
that is of course bogus when no capture is going on at all).
Post by Bo Shen
Thus, keep track of the desired playback and capture clock dividers
separately, and allow changing rates without closing the stream.
---
sound/soc/atmel/atmel_ssc_dai.c | 31 ++++++++++++++++++++++------
---
sound/soc/atmel/atmel_ssc_dai.h | 10 ++++++----
2 files changed, 28 insertions(+), 13 deletions(-)
diff --git a/sound/soc/atmel/atmel_ssc_dai.c
b/sound/soc/atmel/atmel_ssc_dai.c index f403f39..fec14fb 100644
--- a/sound/soc/atmel/atmel_ssc_dai.c
+++ b/sound/soc/atmel/atmel_ssc_dai.c
@@ -277,7 +277,8 @@ static void atmel_ssc_shutdown(struct
snd_pcm_substream *substream,
/* Reset the SSC */
ssc_writel(ssc_p->ssc->regs, CR, SSC_BIT(CR_SWRST));
/* Clear the SSC dividers */
- ssc_p->cmr_div = ssc_p->tcmr_period = ssc_p->rcmr_period
= 0;
+ ssc_p->tcmr_div = ssc_p->rcmr_div = 0;
+ ssc_p->tcmr_period = ssc_p->rcmr_period = 0;
}
spin_unlock_irq(&ssc_p->lock);
}
@@ -304,17 +305,27 @@ static int atmel_ssc_set_dai_clkdiv(struct
snd_soc_dai *cpu_dai,
struct atmel_ssc_info *ssc_p = &ssc_info[cpu_dai->id];
switch (div_id) {
/*
* The same master clock divider is used for both
* transmit and receive, so if a value has already
- * been set, it must match this value.
+ * been set for the other direction, it must match
+ * this value.
*/
- if (ssc_p->cmr_div == 0)
- ssc_p->cmr_div = div;
- else
- if (div != ssc_p->cmr_div)
- return -EBUSY;
+ if (ssc_p->rcmr_div == 0)
+ ssc_p->tcmr_div = div;
+ else if (div != ssc_p->rcmr_div)
+ return -EBUSY;
+ break;
+
+ /*
+ * See ATMEL_SSC_TCMR_DIV.
+ */
+ if (ssc_p->tcmr_div == 0)
+ ssc_p->rcmr_div = div;
+ else if (div != ssc_p->tcmr_div)
+ return -EBUSY;
break;
@@ -345,6 +356,7 @@ static int atmel_ssc_hw_params(struct
snd_pcm_substream *substream,
struct atmel_pcm_dma_params *dma_params;
int dir, channels, bits;
u32 tfmr, rfmr, tcmr, rcmr;
+ u16 cmr;
should be u32.
Ok, I'll send an updated patch later.
Post by Bo Shen
int start_event;
int ret;
int fslen, fslen_ext;
@@ -626,7 +638,8 @@ static int atmel_ssc_hw_params(struct
snd_pcm_substream *substream,
}
/* set SSC clock mode register */
- ssc_writel(ssc_p->ssc->regs, CMR, ssc_p->cmr_div);
+ cmr = ssc_p->tcmr_div ? ssc_p->tcmr_div : ssc_p->rcmr_div;
+ ssc_writel(ssc_p->ssc->regs, CMR, cmr);
/* set receive clock mode and format */
ssc_writel(ssc_p->ssc->regs, RCMR, rcmr); diff --git
a/sound/soc/atmel/atmel_ssc_dai.h b/sound/soc/atmel/atmel_ssc_dai.h
index b1f08d5..a25df7a 100644
--- a/sound/soc/atmel/atmel_ssc_dai.h
+++ b/sound/soc/atmel/atmel_ssc_dai.h
@@ -39,9 +39,10 @@
#define ATMEL_SYSCLK_MCK 0 /* SSC uses AT91 MCK as system
clock */
/* SSC divider ids */
-#define ATMEL_SSC_CMR_DIV 0 /* MCK divider for BCLK */
-#define ATMEL_SSC_TCMR_PERIOD 1 /* BCLK divider for transmit FS */
-#define ATMEL_SSC_RCMR_PERIOD 2 /* BCLK divider for receive FS */
+#define ATMEL_SSC_TCMR_DIV 0 /* MCK divider for transmit BCLK */
+#define ATMEL_SSC_RCMR_DIV 1 /* MCK divider for receive BCLK */
+#define ATMEL_SSC_TCMR_PERIOD 2 /* BCLK divider for transmit
FS */
+#define ATMEL_SSC_RCMR_PERIOD 3 /* BCLK divider for receive
FS */
/*
* SSC direction masks
*/
@@ -110,7 +111,8 @@ struct atmel_ssc_info {
unsigned short dir_mask; /* 0=unused, 1=playback, 2=capture
*/
unsigned short initialized; /* true if SSC has been initialized */
unsigned short daifmt;
- unsigned short cmr_div;
+ unsigned short tcmr_div;
+ unsigned short rcmr_div;
unsigned short tcmr_period;
unsigned short rcmr_period;
struct atmel_pcm_dma_params *dma_params[2];
Best Regards,
Bo Shen
Cheers,
Peter
Bo Shen
2014-10-21 09:00:56 UTC
Permalink
Hi Peter,
Post by Peter Rosin
Hi!
(and thank you for the pointer to the example with the ssc-dai in master mode)
Post by Bo Shen
Hi Peter,
From 1e5621d7b9887c648d1a66238dc82d715c1e2cad Mon Sep 17 00:00:00 2001
Date: Mon, 20 Oct 2014 14:38:04 +0200
Subject: [PATCH] ASoC: atmel_ssc_dai: Track playback and capture CMR
dividers
separately.
The CMR divider register is shared by playback and capture. The SSC
driver therefore tries to enforce rules so that the needed register
content do not conflict during simultaneous playback/capture. However,
the implementation also prevents changing the register content in a
half-duplex scenario, which is needed when changing sample rates.
- when playback, first playback 48kHz, and then playback 8Khz, the 8Khz still
playback in 48kHz mode?
or other things?
I do not know exactly why the problem occurs, but it might be connected to
the library (proprietary) we are using. It apparently uses the OSS interface
and somehow it opens a stream and changes the playback sample-rate a
couple of time before it settles on something. I don't know why this is
done, and I have no control over it. The end result is that without this patch,
the ssc-dai driver returns -EBUSY when the library changes the playback
sample-rate (the driver returns -EBUSY because it thinks that the new
sample rate does not match a previously given capture sample-rate, but
that is of course bogus when no capture is going on at all).
If this issue is caused by your proprietary library, please fix in the
library.

I don't know how this code can fix your issue and also there is no
improvement to the code and it absolutely increase work (choose which
clock to configure: tcmr or rcmr) for the SSC work in master. And also
this patch may confuse the end user, let them thinking the clock for
tcmr and rcmr can configure seperately.

So, I think keep the code as is (without this patch applied), what's
your opinion?
Post by Peter Rosin
Post by Bo Shen
Thus, keep track of the desired playback and capture clock dividers
separately, and allow changing rates without closing the stream.
---
sound/soc/atmel/atmel_ssc_dai.c | 31 ++++++++++++++++++++++------
---
sound/soc/atmel/atmel_ssc_dai.h | 10 ++++++----
2 files changed, 28 insertions(+), 13 deletions(-)
diff --git a/sound/soc/atmel/atmel_ssc_dai.c
b/sound/soc/atmel/atmel_ssc_dai.c index f403f39..fec14fb 100644
--- a/sound/soc/atmel/atmel_ssc_dai.c
+++ b/sound/soc/atmel/atmel_ssc_dai.c
@@ -277,7 +277,8 @@ static void atmel_ssc_shutdown(struct
snd_pcm_substream *substream,
/* Reset the SSC */
ssc_writel(ssc_p->ssc->regs, CR, SSC_BIT(CR_SWRST));
/* Clear the SSC dividers */
- ssc_p->cmr_div = ssc_p->tcmr_period = ssc_p->rcmr_period
= 0;
+ ssc_p->tcmr_div = ssc_p->rcmr_div = 0;
+ ssc_p->tcmr_period = ssc_p->rcmr_period = 0;
}
spin_unlock_irq(&ssc_p->lock);
}
@@ -304,17 +305,27 @@ static int atmel_ssc_set_dai_clkdiv(struct
snd_soc_dai *cpu_dai,
struct atmel_ssc_info *ssc_p = &ssc_info[cpu_dai->id];
switch (div_id) {
/*
* The same master clock divider is used for both
* transmit and receive, so if a value has already
- * been set, it must match this value.
+ * been set for the other direction, it must match
+ * this value.
*/
- if (ssc_p->cmr_div == 0)
- ssc_p->cmr_div = div;
- else
- if (div != ssc_p->cmr_div)
- return -EBUSY;
+ if (ssc_p->rcmr_div == 0)
+ ssc_p->tcmr_div = div;
+ else if (div != ssc_p->rcmr_div)
+ return -EBUSY;
+ break;
+
+ /*
+ * See ATMEL_SSC_TCMR_DIV.
+ */
+ if (ssc_p->tcmr_div == 0)
+ ssc_p->rcmr_div = div;
+ else if (div != ssc_p->tcmr_div)
+ return -EBUSY;
break;
@@ -345,6 +356,7 @@ static int atmel_ssc_hw_params(struct
snd_pcm_substream *substream,
struct atmel_pcm_dma_params *dma_params;
int dir, channels, bits;
u32 tfmr, rfmr, tcmr, rcmr;
+ u16 cmr;
should be u32.
Ok, I'll send an updated patch later.
Post by Bo Shen
int start_event;
int ret;
int fslen, fslen_ext;
@@ -626,7 +638,8 @@ static int atmel_ssc_hw_params(struct
snd_pcm_substream *substream,
}
/* set SSC clock mode register */
- ssc_writel(ssc_p->ssc->regs, CMR, ssc_p->cmr_div);
+ cmr = ssc_p->tcmr_div ? ssc_p->tcmr_div : ssc_p->rcmr_div;
+ ssc_writel(ssc_p->ssc->regs, CMR, cmr);
/* set receive clock mode and format */
ssc_writel(ssc_p->ssc->regs, RCMR, rcmr); diff --git
a/sound/soc/atmel/atmel_ssc_dai.h b/sound/soc/atmel/atmel_ssc_dai.h
index b1f08d5..a25df7a 100644
--- a/sound/soc/atmel/atmel_ssc_dai.h
+++ b/sound/soc/atmel/atmel_ssc_dai.h
@@ -39,9 +39,10 @@
#define ATMEL_SYSCLK_MCK 0 /* SSC uses AT91 MCK as system
clock */
/* SSC divider ids */
-#define ATMEL_SSC_CMR_DIV 0 /* MCK divider for BCLK */
-#define ATMEL_SSC_TCMR_PERIOD 1 /* BCLK divider for transmit FS */
-#define ATMEL_SSC_RCMR_PERIOD 2 /* BCLK divider for receive FS */
+#define ATMEL_SSC_TCMR_DIV 0 /* MCK divider for transmit BCLK */
+#define ATMEL_SSC_RCMR_DIV 1 /* MCK divider for receive BCLK */
+#define ATMEL_SSC_TCMR_PERIOD 2 /* BCLK divider for transmit
FS */
+#define ATMEL_SSC_RCMR_PERIOD 3 /* BCLK divider for receive
FS */
/*
* SSC direction masks
*/
@@ -110,7 +111,8 @@ struct atmel_ssc_info {
unsigned short dir_mask; /* 0=unused, 1=playback, 2=capture
*/
unsigned short initialized; /* true if SSC has been initialized */
unsigned short daifmt;
- unsigned short cmr_div;
+ unsigned short tcmr_div;
+ unsigned short rcmr_div;
unsigned short tcmr_period;
unsigned short rcmr_period;
struct atmel_pcm_dma_params *dma_params[2];
Best Regards,
Bo Shen
Cheers,
Peter
Best Regards,
Bo Shen
Peter Rosin
2014-10-21 11:02:57 UTC
Permalink
Hi again!
Post by Bo Shen
Hi Peter,
Post by Peter Rosin
Hi!
(and thank you for the pointer to the example with the ssc-dai in master mode)
Post by Bo Shen
Hi Peter,
From 1e5621d7b9887c648d1a66238dc82d715c1e2cad Mon Sep 17
00:00:00
Post by Peter Rosin
Post by Bo Shen
2001
Date: Mon, 20 Oct 2014 14:38:04 +0200
Subject: [PATCH] ASoC: atmel_ssc_dai: Track playback and capture CMR
dividers
separately.
The CMR divider register is shared by playback and capture. The SSC
driver therefore tries to enforce rules so that the needed register
content do not conflict during simultaneous playback/capture.
However, the implementation also prevents changing the register
content in a half-duplex scenario, which is needed when changing
sample rates.
Post by Peter Rosin
Post by Bo Shen
- when playback, first playback 48kHz, and then playback 8Khz,
the 8Khz still playback in 48kHz mode?
or other things?
I do not know exactly why the problem occurs, but it might be
connected to the library (proprietary) we are using. It apparently
uses the OSS interface and somehow it opens a stream and changes the
playback sample-rate a couple of time before it settles on something.
I don't know why this is done, and I have no control over it. The end
result is that without this patch, the ssc-dai driver returns -EBUSY
when the library changes the playback sample-rate (the driver returns
-EBUSY because it thinks that the new sample rate does not match a
previously given capture sample-rate, but that is of course bogus when no
capture is going on at all).
If this issue is caused by your proprietary library, please fix in the library.
Ah, but it's not "our" proprietary library to fix, it's simply a library that we
are using (speech synthesis, not our area of expertise). So, I'm not in a
position to simply fix it, as I have no source code.
Post by Bo Shen
I don't know how this code can fix your issue and also there is no
improvement to the code and it absolutely increase work (choose which
clock to configure: tcmr or rcmr) for the SSC work in master. And also this
patch may confuse the end user, let them thinking the clock for tcmr and
rcmr can configure seperately.
I added some traces to our hw_params and got the following (without the patch):

[ 161.170000] atmel ssc startup
[ 161.170000] TFA9879: axentia_asoc_tfa9879_hw_params - mclk rate 66000000
[ 161.180000] TFA9879: axentia_asoc_tfa9879_hw_params - bclk rate 128000
[ 161.180000] TFA9879: axentia_asoc_tfa9879_hw_params - bclk divider 128
[ 161.190000] TFA9879: axentia_asoc_tfa9879_hw_params - period 7
[ 161.200000] TFA9879: axentia_asoc_tfa9879_hw_params - mclk rate 66000000
[ 161.200000] TFA9879: axentia_asoc_tfa9879_hw_params - bclk rate 128000
[ 161.210000] TFA9879: axentia_asoc_tfa9879_hw_params - bclk divider 128
[ 161.220000] TFA9879: axentia_asoc_tfa9879_hw_params - period 7
[ 161.230000] TFA9879: axentia_asoc_tfa9879_hw_params - mclk rate 66000000
[ 161.230000] TFA9879: axentia_asoc_tfa9879_hw_params - bclk rate 256000
[ 161.240000] TFA9879: axentia_asoc_tfa9879_hw_params - bclk divider 64
[ 161.250000] TFA9879: axentia_asoc_tfa9879_hw_params - Failed to set cpu dai clk divider
[ 161.260000] axentia-tfa9879-audio sound.9: ASoC: machine hw_params failed: -16
Post by Bo Shen
So, I think keep the code as is (without this patch applied), what's your
opinion?
In that case we'll simply carry the patch ourselves. I don't know why the above
happens, or if it is caused by bad behavior in the library, or what. But I do know
that the library is unusable for us without some action.

I thought it was an improvement, and therefore sent the patch...

Cheers,
Peter
Peter Rosin
2014-10-21 13:05:15 UTC
Permalink
Hi again,
-----Original Message-----
From: Peter Rosin
Sent: Tuesday, October 21, 2014 13:05
To: 'Bo Shen'
Cc: Liam Girdwood; Mark Brown; Jaroslav Kysela; Takashi Iwai; 'alsa-
Subject: RE: [alsa-devel] [PATCH] ASoC: atmel_ssc_dai: Track playback and
capture CMR dividers separately.
Hi again!
Post by Bo Shen
Hi Peter,
Post by Peter Rosin
Hi!
(and thank you for the pointer to the example with the ssc-dai in master mode)
Post by Bo Shen
Hi Peter,
From 1e5621d7b9887c648d1a66238dc82d715c1e2cad Mon Sep 17
00:00:00
Post by Peter Rosin
Post by Bo Shen
2001
Date: Mon, 20 Oct 2014 14:38:04 +0200
Subject: [PATCH] ASoC: atmel_ssc_dai: Track playback and capture
CMR
Post by Bo Shen
Post by Peter Rosin
Post by Bo Shen
dividers
separately.
The CMR divider register is shared by playback and capture. The SSC
driver therefore tries to enforce rules so that the needed register
content do not conflict during simultaneous playback/capture.
However, the implementation also prevents changing the register
content in a half-duplex scenario, which is needed when changing
sample rates.
Post by Peter Rosin
Post by Bo Shen
- when playback, first playback 48kHz, and then playback 8Khz,
the 8Khz still playback in 48kHz mode?
or other things?
I do not know exactly why the problem occurs, but it might be
connected to the library (proprietary) we are using. It apparently
uses the OSS interface and somehow it opens a stream and changes the
playback sample-rate a couple of time before it settles on something.
I don't know why this is done, and I have no control over it. The end
result is that without this patch, the ssc-dai driver returns -EBUSY
when the library changes the playback sample-rate (the driver returns
-EBUSY because it thinks that the new sample rate does not match a
previously given capture sample-rate, but that is of course bogus when
no
Post by Bo Shen
capture is going on at all).
If this issue is caused by your proprietary library, please fix in the library.
Ah, but it's not "our" proprietary library to fix, it's simply a library that we
are using (speech synthesis, not our area of expertise). So, I'm not in a
position to simply fix it, as I have no source code.
Post by Bo Shen
I don't know how this code can fix your issue and also there is no
improvement to the code and it absolutely increase work (choose which
clock to configure: tcmr or rcmr) for the SSC work in master. And also this
patch may confuse the end user, let them thinking the clock for tcmr and
rcmr can configure seperately.
I added some traces to our hw_params and got the following (without the
[ 161.170000] atmel ssc startup
[ 161.170000] TFA9879: axentia_asoc_tfa9879_hw_params - mclk rate
66000000
[ 161.180000] TFA9879: axentia_asoc_tfa9879_hw_params - bclk rate 128000
[ 161.180000] TFA9879: axentia_asoc_tfa9879_hw_params - bclk divider 128
[ 161.190000] TFA9879: axentia_asoc_tfa9879_hw_params - period 7
[ 161.200000] TFA9879: axentia_asoc_tfa9879_hw_params - mclk rate
66000000
[ 161.200000] TFA9879: axentia_asoc_tfa9879_hw_params - bclk rate 128000
[ 161.210000] TFA9879: axentia_asoc_tfa9879_hw_params - bclk divider 128
[ 161.220000] TFA9879: axentia_asoc_tfa9879_hw_params - period 7
[ 161.230000] TFA9879: axentia_asoc_tfa9879_hw_params - mclk rate
66000000
[ 161.230000] TFA9879: axentia_asoc_tfa9879_hw_params - bclk rate 256000
[ 161.240000] TFA9879: axentia_asoc_tfa9879_hw_params - bclk divider 64
[ 161.250000] TFA9879: axentia_asoc_tfa9879_hw_params - Failed to set cpu
dai clk divider
[ 161.260000] axentia-tfa9879-audio sound.9: ASoC: machine hw_params
failed: -16
I did some further tests, and the following program fails without the patch:

#include <sys/ioctl.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/soundcard.h>

int
main(void)
{
int fd;
int format;
int channels;

if ((fd = open("/dev/dsp", O_WRONLY, 0)) == -1) {
perror("open");
return 1;
}
format = AFMT_S16_LE;
if (ioctl(fd, SNDCTL_DSP_SETFMT, &format) == -1) {
perror("SNDCTL_DSP_SETFMT");
return 1;
}
channels = 2;
if (ioctl(fd, SNDCTL_DSP_CHANNELS, &channels) == -1) {
perror("SNDCTL_DSP_CHANNELS");
return 1;
}
return 0;
}

Output:
SNDCTL_DSP_CHANNELS: Device or resource busy

(I admin to having edited the above code slightly in this mail, so I might have
introduced some silly bug, but you get what I mean, just open the device
and request some parameters, and boom: -EBUSY)

Cheers,
Peter
Post by Bo Shen
So, I think keep the code as is (without this patch applied), what's your
opinion?
In that case we'll simply carry the patch ourselves. I don't know why the
above
happens, or if it is caused by bad behavior in the library, or what. But I do
know
that the library is unusable for us without some action.
I thought it was an improvement, and therefore sent the patch...
Cheers,
Peter
Bo Shen
2014-10-22 01:27:15 UTC
Permalink
Hi Peter,
With the patch, it is OK?
Post by Peter Rosin
#include <sys/ioctl.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/soundcard.h>
int
main(void)
{
int fd;
int format;
int channels;
if ((fd = open("/dev/dsp", O_WRONLY, 0)) == -1) {
perror("open");
return 1;
}
format = AFMT_S16_LE;
if (ioctl(fd, SNDCTL_DSP_SETFMT, &format) == -1) {
perror("SNDCTL_DSP_SETFMT");
return 1;
}
channels = 2;
if (ioctl(fd, SNDCTL_DSP_CHANNELS, &channels) == -1) {
perror("SNDCTL_DSP_CHANNELS");
return 1;
}
return 0;
}
SNDCTL_DSP_CHANNELS: Device or resource busy
This return from codec or from atmel_ssc_dai?
Post by Peter Rosin
(I admin to having edited the above code slightly in this mail, so I might have
introduced some silly bug, but you get what I mean, just open the device
and request some parameters, and boom: -EBUSY)
Cheers,
Peter
Best Regards,
Bo Shen
Peter Rosin
2014-10-22 04:47:21 UTC
Permalink
Hi!
Post by Bo Shen
Hi Peter,
With the patch, it is OK?
Yes.
Post by Bo Shen
Post by Peter Rosin
#include <sys/ioctl.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/soundcard.h>
int
main(void)
{
int fd;
int format;
int channels;
if ((fd = open("/dev/dsp", O_WRONLY, 0)) == -1) {
perror("open");
return 1;
}
format = AFMT_S16_LE;
if (ioctl(fd, SNDCTL_DSP_SETFMT, &format) == -1) {
perror("SNDCTL_DSP_SETFMT");
return 1;
}
channels = 2;
if (ioctl(fd, SNDCTL_DSP_CHANNELS, &channels) == -1) {
perror("SNDCTL_DSP_CHANNELS");
return 1;
}
return 0;
}
SNDCTL_DSP_CHANNELS: Device or resource busy
This return from codec or from atmel_ssc_dai?
This -EBUSY definitely comes from atmel_ssc_set_dai_sysclk, when my
card-driver tries to set ATMEL_SSC_CMR_DIV. With the patch, it works.
(the codec is spdif-transmitter, since the i2c interface of the actual tfa9879
codec is not directly reachable from the linux cpu, but that has nothing to
do with this issue).
Post by Bo Shen
Post by Peter Rosin
(I admin to having edited the above code slightly in this mail, so I
s/admin/admit/
Post by Bo Shen
Post by Peter Rosin
might have introduced some silly bug, but you get what I mean, just
open the device and request some parameters, and boom: -EBUSY)
Cheers,
Peter
Bo Shen
2014-10-22 08:09:36 UTC
Permalink
Hi Peter,
Post by Peter Rosin
Hi!
Post by Bo Shen
Hi Peter,
With the patch, it is OK?
Yes.
Post by Bo Shen
Post by Peter Rosin
#include <sys/ioctl.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/soundcard.h>
int
main(void)
{
int fd;
int format;
int channels;
if ((fd = open("/dev/dsp", O_WRONLY, 0)) == -1) {
perror("open");
return 1;
}
format = AFMT_S16_LE;
if (ioctl(fd, SNDCTL_DSP_SETFMT, &format) == -1) {
perror("SNDCTL_DSP_SETFMT");
return 1;
}
channels = 2;
if (ioctl(fd, SNDCTL_DSP_CHANNELS, &channels) == -1) {
perror("SNDCTL_DSP_CHANNELS");
return 1;
}
return 0;
}
SNDCTL_DSP_CHANNELS: Device or resource busy
This return from codec or from atmel_ssc_dai?
This -EBUSY definitely comes from atmel_ssc_set_dai_sysclk, when my
card-driver tries to set ATMEL_SSC_CMR_DIV. With the patch, it works.
(the codec is spdif-transmitter, since the i2c interface of the actual tfa9879
codec is not directly reachable from the linux cpu, but that has nothing to
do with this issue).
I try to reproduce it (using the code your pasted directly) on atmel
sama5d3xek with wm8904 code, don't meet this error.

I also go through the OSS code, I still don't find this is related with
atmel_ssc_set_dai_sysclk.

So, am I missing something or something else?
Post by Peter Rosin
Post by Bo Shen
Post by Peter Rosin
(I admin to having edited the above code slightly in this mail, so I
s/admin/admit/
Post by Bo Shen
Post by Peter Rosin
might have introduced some silly bug, but you get what I mean, just
open the device and request some parameters, and boom: -EBUSY)
Cheers,
Peter
Best Regards,
Bo Shen
Peter Rosin
2014-10-22 08:33:29 UTC
Permalink
Hi!
Post by Bo Shen
Post by Peter Rosin
Post by Bo Shen
With the patch, it is OK?
Yes.
Post by Bo Shen
Post by Peter Rosin
#include <sys/ioctl.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/soundcard.h>
int
main(void)
{
int fd;
int format;
int channels;
if ((fd = open("/dev/dsp", O_WRONLY, 0)) == -1) {
perror("open");
return 1;
}
format = AFMT_S16_LE;
if (ioctl(fd, SNDCTL_DSP_SETFMT, &format) == -1) {
perror("SNDCTL_DSP_SETFMT");
return 1;
}
channels = 2;
if (ioctl(fd, SNDCTL_DSP_CHANNELS, &channels) == -1) {
perror("SNDCTL_DSP_CHANNELS");
return 1;
}
return 0;
}
SNDCTL_DSP_CHANNELS: Device or resource busy
This return from codec or from atmel_ssc_dai?
This -EBUSY definitely comes from atmel_ssc_set_dai_sysclk, when my
card-driver tries to set ATMEL_SSC_CMR_DIV. With the patch, it works.
(the codec is spdif-transmitter, since the i2c interface of the actual
tfa9879 codec is not directly reachable from the linux cpu, but that
has nothing to do with this issue).
I try to reproduce it (using the code your pasted directly) on atmel
sama5d3xek with wm8904 code, don't meet this error.
I also go through the OSS code, I still don't find this is related with
atmel_ssc_set_dai_sysclk.
So, am I missing something or something else?
The sama5d3xek/wm9804 combo, as implemented in the kernel, has the
ssc dai in slave mode, and therefore don't need to fiddle with any
ssc dai dividers (atmel_9804.c :atmel_asoc_wm9804_hw_params() only
sets things in the wm9804 codec dai driver and leaves the ssc dai to itself).

Instead, try the above code on your code with the ssc dai in master mode
that you pointed at previously.

https://github.com/Android4SAM/linux-at91/commit/33db8ebd3e75632c482dda271340f4d2adcfd320

If that happens to not hit -EBUSY (which it might not, since the wm9804 codec
will only allow stereo, so the SNDCTL_DSP_CHANNELS ioctl might not need
to make any change for any ssc divider) add code to also set a non-default
sample rate, e.g.:

speed = 22050;
if (ioctl(fd, SNDCTL_DSP_SPEED, &speed) == -1) {
perror("SNDCTL_DSP_SPEED");
return 1;
}

Cheers,
Peter
Bo Shen
2014-10-22 09:23:01 UTC
Permalink
Hi Peter,
Post by Peter Rosin
The sama5d3xek/wm9804 combo, as implemented in the kernel, has the
ssc dai in slave mode, and therefore don't need to fiddle with any
ssc dai dividers (atmel_9804.c :atmel_asoc_wm9804_hw_params() only
sets things in the wm9804 codec dai driver and leaves the ssc dai to itself).
Instead, try the above code on your code with the ssc dai in master mode
that you pointed at previously.
Yes, I try the ssc working as master mode.
Post by Peter Rosin
https://github.com/Android4SAM/linux-at91/commit/33db8ebd3e75632c482dda271340f4d2adcfd320
If that happens to not hit -EBUSY (which it might not, since the wm9804 codec
will only allow stereo, so the SNDCTL_DSP_CHANNELS ioctl might not need
to make any change for any ssc divider) add code to also set a non-default
speed = 22050;
if (ioctl(fd, SNDCTL_DSP_SPEED, &speed) == -1) {
perror("SNDCTL_DSP_SPEED");
return 1;
}
with this piece of code, I reproduce your issue.

Now, I know the reason of this issue, work in oss mode, it will set the
default clock to 8KHz, and then if change to other sample rate, for
example 48KHz, the div is different, then it reports -EBUSY.

So, I think we won't change the ATMEL_SSC_CMR_DIV to ATMEL_SSC_TCMR_DIV
and ATMEL_SSC_RCMR_DIV, as it will affect other users. We just deal with
this situation in ATMEL_SSC_CMR_DIV block, check the direction, if the
same direction change the div, then accept the change, otherwise, return
-EBUSY.
Post by Peter Rosin
Cheers,
Peter
Best Regards,
Bo Shen
Peter Rosin
2014-10-22 11:42:18 UTC
Permalink
Post by Bo Shen
with this piece of code, I reproduce your issue.
Now, I know the reason of this issue, work in oss mode, it will set the default
clock to 8KHz, and then if change to other sample rate, for example 48KHz,
the div is different, then it reports -EBUSY.
Indeed.
Post by Bo Shen
So, I think we won't change the ATMEL_SSC_CMR_DIV to
ATMEL_SSC_TCMR_DIV and ATMEL_SSC_RCMR_DIV, as it will affect other
users. We just deal with this situation in ATMEL_SSC_CMR_DIV block, check
the direction, if the same direction change the div, then accept the change,
otherwise, return -EBUSY.
Ok.

But I'm not sure it is possible to dig out the current direction in the
.set_clkdiv callback? Perhaps the correct fix is to set the bits
.symmetric_rates, .symmetric_channels and .symmetric_samplebits
in the atmel_ssc_dai struct when the ssc dai is master? Then I
expect that other mechanisms will kick in that will render the current
CMR_DIV check pointless?

Is a dai driver allowed to change these symmetry bits after registration?
Can they be set in the .set_sysclk callback? Perhaps in the
ATMEL_SSC_CMR_DIV block itself? That callback should only be
called when the dai is master, so that would be perfect...

Yes, the limitation would be a little bit more strict than today, but is it
really common to require different modes on playback and capture?

Cheers,
Peter

Loading...