[PATCH 0/5] ASoC: cirrus: Series of fixes for ep93xx-i2s

[PATCH 0/5] ASoC: cirrus: Series of fixes for ep93xx-i2s

[Alexander Sverdlin]

This series is a result of long-running debugging of rarely screwed I2S
stream out of EP9302 chip. Logic analyser shows that the stream is shifted
by one byte (out of 32 bits per sample) which leads to noise intead of
original stream.

DMA is verified to work fine (no underrun). The issue is only reproducible
under high load (CPU or AMBA bus -- not yet clear). This stream corruption
happens at the same time I2S controller reports internal FIFO underrun
(even though according to documentation, it should handle an underrun
gracefully).

First two patches are fixing unrelated issues in I2S driver found during
debugging of the stream shift. Third one is simplification of the driver
to prepare for workaround.

Both controller configuration options for TX FIFO underrun handling were
tested, both do not work reliable. Hence, this ugly watchdog in the last
patch.

The whole series is tested on a board similar to EDB9302 (identical in
sound part).

Alexander Sverdlin (5):
  ASoC: cirrus: i2s: Fix LRCLK configuration
  ASoC: cirrus: i2s: Fix {TX|RX}LinCtrlData setup
  ASoC: cirrus: i2s: Stop enabling I2S2 and I2S3 FIFOs
  ARM: ep93xx: i2s: Add IRQ to platform device resources
  ASoC: cirrus: i2s: IRQ-based stream watchdog

 arch/arm/mach-ep93xx/core.c    |   1 +
 sound/soc/cirrus/Kconfig       |  17 +++++++
 sound/soc/cirrus/edb93xx.c     |   2 +-
 sound/soc/cirrus/ep93xx-i2s.c  | 106 +++++++++++++++++++++++++++++++++--------
 sound/soc/cirrus/snappercl15.c |   2 +-
 5 files changed, 106 insertions(+), 22 deletions(-)

-- 
2.16.2

[PATCH 1/5] ASoC: cirrus: i2s: Fix LRCLK configuration

[Alexander Sverdlin]

The bit responsible for LRCLK polarity is i2s_tlrs (0), not i2s_trel (2)
(refer to "EP93xx User's Guide").

Previously card drivers which specified SND_SOC_DAIFMT_NB_IF actually got
SND_SOC_DAIFMT_NB_NF, an adaptation is necessary to retain the old
behavior.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
---
 sound/soc/cirrus/edb93xx.c     | 2 +-
 sound/soc/cirrus/ep93xx-i2s.c  | 8 ++++----
 sound/soc/cirrus/snappercl15.c | 2 +-
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/sound/soc/cirrus/edb93xx.c b/sound/soc/cirrus/edb93xx.c
index c53bd6f2c2d7..3d011abaa266 100644
--- a/sound/soc/cirrus/edb93xx.c
+++ b/sound/soc/cirrus/edb93xx.c
@@ -67,7 +67,7 @@ static struct snd_soc_dai_link edb93xx_dai = {
 	.cpu_dai_name	= "ep93xx-i2s",
 	.codec_name	= "spi0.0",
 	.codec_dai_name	= "cs4271-hifi",
-	.dai_fmt	= SND_SOC_DAIFMT_I2S | SND_SOC_DAIFMT_NB_IF |
+	.dai_fmt	= SND_SOC_DAIFMT_I2S | SND_SOC_DAIFMT_NB_NF |
 			  SND_SOC_DAIFMT_CBS_CFS,
 	.ops		= &edb93xx_ops,
 };
diff --git a/sound/soc/cirrus/ep93xx-i2s.c b/sound/soc/cirrus/ep93xx-i2s.c
index 934f8aefdd90..38c240c97041 100644
--- a/sound/soc/cirrus/ep93xx-i2s.c
+++ b/sound/soc/cirrus/ep93xx-i2s.c
@@ -213,24 +213,24 @@ static int ep93xx_i2s_set_dai_fmt(struct snd_soc_dai *cpu_dai,
 	switch (fmt & SND_SOC_DAIFMT_INV_MASK) {
 	case SND_SOC_DAIFMT_NB_NF:
 		/* Negative bit clock, lrclk low on left word */
-		clk_cfg &= ~(EP93XX_I2S_CLKCFG_CKP | EP93XX_I2S_CLKCFG_REL);
+		clk_cfg &= ~(EP93XX_I2S_CLKCFG_CKP | EP93XX_I2S_CLKCFG_LRS);
 		break;
 
 	case SND_SOC_DAIFMT_NB_IF:
 		/* Negative bit clock, lrclk low on right word */
 		clk_cfg &= ~EP93XX_I2S_CLKCFG_CKP;
-		clk_cfg |= EP93XX_I2S_CLKCFG_REL;
+		clk_cfg |= EP93XX_I2S_CLKCFG_LRS;
 		break;
 
 	case SND_SOC_DAIFMT_IB_NF:
 		/* Positive bit clock, lrclk low on left word */
 		clk_cfg |= EP93XX_I2S_CLKCFG_CKP;
-		clk_cfg &= ~EP93XX_I2S_CLKCFG_REL;
+		clk_cfg &= ~EP93XX_I2S_CLKCFG_LRS;
 		break;
 
 	case SND_SOC_DAIFMT_IB_IF:
 		/* Positive bit clock, lrclk low on right word */
-		clk_cfg |= EP93XX_I2S_CLKCFG_CKP | EP93XX_I2S_CLKCFG_REL;
+		clk_cfg |= EP93XX_I2S_CLKCFG_CKP | EP93XX_I2S_CLKCFG_LRS;
 		break;
 	}
 
diff --git a/sound/soc/cirrus/snappercl15.c b/sound/soc/cirrus/snappercl15.c
index 2334ec19e7eb..11ff7b2672b2 100644
--- a/sound/soc/cirrus/snappercl15.c
+++ b/sound/soc/cirrus/snappercl15.c
@@ -72,7 +72,7 @@ static struct snd_soc_dai_link snappercl15_dai = {
 	.codec_dai_name	= "tlv320aic23-hifi",
 	.codec_name	= "tlv320aic23-codec.0-001a",
 	.platform_name	= "ep93xx-i2s",
-	.dai_fmt	= SND_SOC_DAIFMT_I2S | SND_SOC_DAIFMT_NB_IF |
+	.dai_fmt	= SND_SOC_DAIFMT_I2S | SND_SOC_DAIFMT_NB_NF |
 			  SND_SOC_DAIFMT_CBS_CFS,
 	.ops		= &snappercl15_ops,
 };
-- 
2.16.2

Applied "ASoC: cirrus: i2s: Fix LRCLK configuration" to the asoc tree

[Mark Brown]

The patch

   ASoC: cirrus: i2s: Fix LRCLK configuration

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 2d534113be9a2aa532a1ae127a57e83558aed358 Mon Sep 17 00:00:00 2001
From: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Date: Sat, 28 Apr 2018 22:51:38 +0200
Subject: [PATCH] ASoC: cirrus: i2s: Fix LRCLK configuration

The bit responsible for LRCLK polarity is i2s_tlrs (0), not i2s_trel (2)
(refer to "EP93xx User's Guide").

Previously card drivers which specified SND_SOC_DAIFMT_NB_IF actually got
SND_SOC_DAIFMT_NB_NF, an adaptation is necessary to retain the old
behavior.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable at vger.kernel.org
---
 sound/soc/cirrus/edb93xx.c     | 2 +-
 sound/soc/cirrus/ep93xx-i2s.c  | 8 ++++----
 sound/soc/cirrus/snappercl15.c | 2 +-
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/sound/soc/cirrus/edb93xx.c b/sound/soc/cirrus/edb93xx.c
index c53bd6f2c2d7..3d011abaa266 100644
--- a/sound/soc/cirrus/edb93xx.c
+++ b/sound/soc/cirrus/edb93xx.c
@@ -67,7 +67,7 @@ static struct snd_soc_dai_link edb93xx_dai = {
 	.cpu_dai_name	= "ep93xx-i2s",
 	.codec_name	= "spi0.0",
 	.codec_dai_name	= "cs4271-hifi",
-	.dai_fmt	= SND_SOC_DAIFMT_I2S | SND_SOC_DAIFMT_NB_IF |
+	.dai_fmt	= SND_SOC_DAIFMT_I2S | SND_SOC_DAIFMT_NB_NF |
 			  SND_SOC_DAIFMT_CBS_CFS,
 	.ops		= &edb93xx_ops,
 };
diff --git a/sound/soc/cirrus/ep93xx-i2s.c b/sound/soc/cirrus/ep93xx-i2s.c
index 934f8aefdd90..38c240c97041 100644
--- a/sound/soc/cirrus/ep93xx-i2s.c
+++ b/sound/soc/cirrus/ep93xx-i2s.c
@@ -213,24 +213,24 @@ static int ep93xx_i2s_set_dai_fmt(struct snd_soc_dai *cpu_dai,
 	switch (fmt & SND_SOC_DAIFMT_INV_MASK) {
 	case SND_SOC_DAIFMT_NB_NF:
 		/* Negative bit clock, lrclk low on left word */
-		clk_cfg &= ~(EP93XX_I2S_CLKCFG_CKP | EP93XX_I2S_CLKCFG_REL);
+		clk_cfg &= ~(EP93XX_I2S_CLKCFG_CKP | EP93XX_I2S_CLKCFG_LRS);
 		break;
 
 	case SND_SOC_DAIFMT_NB_IF:
 		/* Negative bit clock, lrclk low on right word */
 		clk_cfg &= ~EP93XX_I2S_CLKCFG_CKP;
-		clk_cfg |= EP93XX_I2S_CLKCFG_REL;
+		clk_cfg |= EP93XX_I2S_CLKCFG_LRS;
 		break;
 
 	case SND_SOC_DAIFMT_IB_NF:
 		/* Positive bit clock, lrclk low on left word */
 		clk_cfg |= EP93XX_I2S_CLKCFG_CKP;
-		clk_cfg &= ~EP93XX_I2S_CLKCFG_REL;
+		clk_cfg &= ~EP93XX_I2S_CLKCFG_LRS;
 		break;
 
 	case SND_SOC_DAIFMT_IB_IF:
 		/* Positive bit clock, lrclk low on right word */
-		clk_cfg |= EP93XX_I2S_CLKCFG_CKP | EP93XX_I2S_CLKCFG_REL;
+		clk_cfg |= EP93XX_I2S_CLKCFG_CKP | EP93XX_I2S_CLKCFG_LRS;
 		break;
 	}
 
diff --git a/sound/soc/cirrus/snappercl15.c b/sound/soc/cirrus/snappercl15.c
index 2334ec19e7eb..11ff7b2672b2 100644
--- a/sound/soc/cirrus/snappercl15.c
+++ b/sound/soc/cirrus/snappercl15.c
@@ -72,7 +72,7 @@ static struct snd_soc_dai_link snappercl15_dai = {
 	.codec_dai_name	= "tlv320aic23-hifi",
 	.codec_name	= "tlv320aic23-codec.0-001a",
 	.platform_name	= "ep93xx-i2s",
-	.dai_fmt	= SND_SOC_DAIFMT_I2S | SND_SOC_DAIFMT_NB_IF |
+	.dai_fmt	= SND_SOC_DAIFMT_I2S | SND_SOC_DAIFMT_NB_NF |
 			  SND_SOC_DAIFMT_CBS_CFS,
 	.ops		= &snappercl15_ops,
 };
-- 
2.17.0

[PATCH 2/5] ASoC: cirrus: i2s: Fix {TX|RX}LinCtrlData setup

[Alexander Sverdlin]

According to "EP93xx User?s Guide", I2STXLinCtrlData and I2SRXLinCtrlData
registers actually have different format. The only currently used bit
(Left_Right_Justify) has different position. Fix this and simplify the
whole setup taking into account the fact that both registers have zero
default value.

The practical effect of the above is repaired SND_SOC_DAIFMT_RIGHT_J
support (currently unused).

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
---
 sound/soc/cirrus/ep93xx-i2s.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/sound/soc/cirrus/ep93xx-i2s.c b/sound/soc/cirrus/ep93xx-i2s.c
index 38c240c97041..0dc3852c4621 100644
--- a/sound/soc/cirrus/ep93xx-i2s.c
+++ b/sound/soc/cirrus/ep93xx-i2s.c
@@ -51,7 +51,9 @@
 #define EP93XX_I2S_WRDLEN_24		(1 << 0)
 #define EP93XX_I2S_WRDLEN_32		(2 << 0)
 
-#define EP93XX_I2S_LINCTRLDATA_R_JUST	(1 << 2) /* Right justify */
+#define EP93XX_I2S_RXLINCTRLDATA_R_JUST	BIT(1) /* Right justify */
+
+#define EP93XX_I2S_TXLINCTRLDATA_R_JUST	BIT(2) /* Right justify */
 
 #define EP93XX_I2S_CLKCFG_LRS		(1 << 0) /* lrclk polarity */
 #define EP93XX_I2S_CLKCFG_CKP		(1 << 1) /* Bit clock polarity */
@@ -170,25 +172,25 @@ static int ep93xx_i2s_set_dai_fmt(struct snd_soc_dai *cpu_dai,
 				  unsigned int fmt)
 {
 	struct ep93xx_i2s_info *info = snd_soc_dai_get_drvdata(cpu_dai);
-	unsigned int clk_cfg, lin_ctrl;
+	unsigned int clk_cfg;
+	unsigned int txlin_ctrl = 0;
+	unsigned int rxlin_ctrl = 0;
 
 	clk_cfg  = ep93xx_i2s_read_reg(info, EP93XX_I2S_RXCLKCFG);
-	lin_ctrl = ep93xx_i2s_read_reg(info, EP93XX_I2S_RXLINCTRLDATA);
 
 	switch (fmt & SND_SOC_DAIFMT_FORMAT_MASK) {
 	case SND_SOC_DAIFMT_I2S:
 		clk_cfg |= EP93XX_I2S_CLKCFG_REL;
-		lin_ctrl &= ~EP93XX_I2S_LINCTRLDATA_R_JUST;
 		break;
 
 	case SND_SOC_DAIFMT_LEFT_J:
 		clk_cfg &= ~EP93XX_I2S_CLKCFG_REL;
-		lin_ctrl &= ~EP93XX_I2S_LINCTRLDATA_R_JUST;
 		break;
 
 	case SND_SOC_DAIFMT_RIGHT_J:
 		clk_cfg &= ~EP93XX_I2S_CLKCFG_REL;
-		lin_ctrl |= EP93XX_I2S_LINCTRLDATA_R_JUST;
+		rxlin_ctrl |= EP93XX_I2S_RXLINCTRLDATA_R_JUST;
+		txlin_ctrl |= EP93XX_I2S_TXLINCTRLDATA_R_JUST;
 		break;
 
 	default:
@@ -237,8 +239,8 @@ static int ep93xx_i2s_set_dai_fmt(struct snd_soc_dai *cpu_dai,
 	/* Write new register values */
 	ep93xx_i2s_write_reg(info, EP93XX_I2S_RXCLKCFG, clk_cfg);
 	ep93xx_i2s_write_reg(info, EP93XX_I2S_TXCLKCFG, clk_cfg);
-	ep93xx_i2s_write_reg(info, EP93XX_I2S_RXLINCTRLDATA, lin_ctrl);
-	ep93xx_i2s_write_reg(info, EP93XX_I2S_TXLINCTRLDATA, lin_ctrl);
+	ep93xx_i2s_write_reg(info, EP93XX_I2S_RXLINCTRLDATA, rxlin_ctrl);
+	ep93xx_i2s_write_reg(info, EP93XX_I2S_TXLINCTRLDATA, txlin_ctrl);
 	return 0;
 }
 
-- 
2.16.2

Applied "ASoC: cirrus: i2s: Fix {TX|RX}LinCtrlData setup" to the asoc tree

[Mark Brown]

The patch

   ASoC: cirrus: i2s: Fix {TX|RX}LinCtrlData setup

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 5d302ed3cc80564fb835bed5fdba1e1250ecc9e5 Mon Sep 17 00:00:00 2001
From: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Date: Sat, 28 Apr 2018 22:51:39 +0200
Subject: [PATCH] ASoC: cirrus: i2s: Fix {TX|RX}LinCtrlData setup
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

According to "EP93xx User???s Guide", I2STXLinCtrlData and I2SRXLinCtrlData
registers actually have different format. The only currently used bit
(Left_Right_Justify) has different position. Fix this and simplify the
whole setup taking into account the fact that both registers have zero
default value.

The practical effect of the above is repaired SND_SOC_DAIFMT_RIGHT_J
support (currently unused).

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable at vger.kernel.org
---
 sound/soc/cirrus/ep93xx-i2s.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/sound/soc/cirrus/ep93xx-i2s.c b/sound/soc/cirrus/ep93xx-i2s.c
index 38c240c97041..0dc3852c4621 100644
--- a/sound/soc/cirrus/ep93xx-i2s.c
+++ b/sound/soc/cirrus/ep93xx-i2s.c
@@ -51,7 +51,9 @@
 #define EP93XX_I2S_WRDLEN_24		(1 << 0)
 #define EP93XX_I2S_WRDLEN_32		(2 << 0)
 
-#define EP93XX_I2S_LINCTRLDATA_R_JUST	(1 << 2) /* Right justify */
+#define EP93XX_I2S_RXLINCTRLDATA_R_JUST	BIT(1) /* Right justify */
+
+#define EP93XX_I2S_TXLINCTRLDATA_R_JUST	BIT(2) /* Right justify */
 
 #define EP93XX_I2S_CLKCFG_LRS		(1 << 0) /* lrclk polarity */
 #define EP93XX_I2S_CLKCFG_CKP		(1 << 1) /* Bit clock polarity */
@@ -170,25 +172,25 @@ static int ep93xx_i2s_set_dai_fmt(struct snd_soc_dai *cpu_dai,
 				  unsigned int fmt)
 {
 	struct ep93xx_i2s_info *info = snd_soc_dai_get_drvdata(cpu_dai);
-	unsigned int clk_cfg, lin_ctrl;
+	unsigned int clk_cfg;
+	unsigned int txlin_ctrl = 0;
+	unsigned int rxlin_ctrl = 0;
 
 	clk_cfg  = ep93xx_i2s_read_reg(info, EP93XX_I2S_RXCLKCFG);
-	lin_ctrl = ep93xx_i2s_read_reg(info, EP93XX_I2S_RXLINCTRLDATA);
 
 	switch (fmt & SND_SOC_DAIFMT_FORMAT_MASK) {
 	case SND_SOC_DAIFMT_I2S:
 		clk_cfg |= EP93XX_I2S_CLKCFG_REL;
-		lin_ctrl &= ~EP93XX_I2S_LINCTRLDATA_R_JUST;
 		break;
 
 	case SND_SOC_DAIFMT_LEFT_J:
 		clk_cfg &= ~EP93XX_I2S_CLKCFG_REL;
-		lin_ctrl &= ~EP93XX_I2S_LINCTRLDATA_R_JUST;
 		break;
 
 	case SND_SOC_DAIFMT_RIGHT_J:
 		clk_cfg &= ~EP93XX_I2S_CLKCFG_REL;
-		lin_ctrl |= EP93XX_I2S_LINCTRLDATA_R_JUST;
+		rxlin_ctrl |= EP93XX_I2S_RXLINCTRLDATA_R_JUST;
+		txlin_ctrl |= EP93XX_I2S_TXLINCTRLDATA_R_JUST;
 		break;
 
 	default:
@@ -237,8 +239,8 @@ static int ep93xx_i2s_set_dai_fmt(struct snd_soc_dai *cpu_dai,
 	/* Write new register values */
 	ep93xx_i2s_write_reg(info, EP93XX_I2S_RXCLKCFG, clk_cfg);
 	ep93xx_i2s_write_reg(info, EP93XX_I2S_TXCLKCFG, clk_cfg);
-	ep93xx_i2s_write_reg(info, EP93XX_I2S_RXLINCTRLDATA, lin_ctrl);
-	ep93xx_i2s_write_reg(info, EP93XX_I2S_TXLINCTRLDATA, lin_ctrl);
+	ep93xx_i2s_write_reg(info, EP93XX_I2S_RXLINCTRLDATA, rxlin_ctrl);
+	ep93xx_i2s_write_reg(info, EP93XX_I2S_TXLINCTRLDATA, txlin_ctrl);
 	return 0;
 }
 
-- 
2.17.0

[PATCH 3/5] ASoC: cirrus: i2s: Stop enabling I2S2 and I2S3 FIFOs

[Alexander Sverdlin]

The driver never supported more than 2 channels because of
ep93xx_i2s_dma_data[] supporting only 1 DMA channel in each
direction.
Stop enabling two unused I2S controller FIFOs, this will simplify
future interrupt support.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
---
 sound/soc/cirrus/ep93xx-i2s.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/sound/soc/cirrus/ep93xx-i2s.c b/sound/soc/cirrus/ep93xx-i2s.c
index 0dc3852c4621..42cc6d22baac 100644
--- a/sound/soc/cirrus/ep93xx-i2s.c
+++ b/sound/soc/cirrus/ep93xx-i2s.c
@@ -98,7 +98,6 @@ static inline unsigned ep93xx_i2s_read_reg(struct ep93xx_i2s_info *info,
 static void ep93xx_i2s_enable(struct ep93xx_i2s_info *info, int stream)
 {
 	unsigned base_reg;
-	int i;
 
 	if ((ep93xx_i2s_read_reg(info, EP93XX_I2S_TX0EN) & 0x1) == 0 &&
 	    (ep93xx_i2s_read_reg(info, EP93XX_I2S_RX0EN) & 0x1) == 0) {
@@ -111,27 +110,24 @@ static void ep93xx_i2s_enable(struct ep93xx_i2s_info *info, int stream)
 		ep93xx_i2s_write_reg(info, EP93XX_I2S_GLCTRL, 1);
 	}
 
-	/* Enable fifos */
+	/* Enable fifo */
 	if (stream == SNDRV_PCM_STREAM_PLAYBACK)
 		base_reg = EP93XX_I2S_TX0EN;
 	else
 		base_reg = EP93XX_I2S_RX0EN;
-	for (i = 0; i < 3; i++)
-		ep93xx_i2s_write_reg(info, base_reg + (i * 4), 1);
+	ep93xx_i2s_write_reg(info, base_reg, 1);
 }
 
 static void ep93xx_i2s_disable(struct ep93xx_i2s_info *info, int stream)
 {
 	unsigned base_reg;
-	int i;
 
-	/* Disable fifos */
+	/* Disable fifo */
 	if (stream == SNDRV_PCM_STREAM_PLAYBACK)
 		base_reg = EP93XX_I2S_TX0EN;
 	else
 		base_reg = EP93XX_I2S_RX0EN;
-	for (i = 0; i < 3; i++)
-		ep93xx_i2s_write_reg(info, base_reg + (i * 4), 0);
+	ep93xx_i2s_write_reg(info, base_reg, 0);
 
 	if ((ep93xx_i2s_read_reg(info, EP93XX_I2S_TX0EN) & 0x1) == 0 &&
 	    (ep93xx_i2s_read_reg(info, EP93XX_I2S_RX0EN) & 0x1) == 0) {
-- 
2.16.2

Applied "ASoC: cirrus: i2s: Stop enabling I2S2 and I2S3 FIFOs" to the asoc tree

[Mark Brown]

The patch

   ASoC: cirrus: i2s: Stop enabling I2S2 and I2S3 FIFOs

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 cc27062b3eee3beb2e3830641b23ba9a52a8a04a Mon Sep 17 00:00:00 2001
From: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Date: Sat, 28 Apr 2018 22:51:40 +0200
Subject: [PATCH] ASoC: cirrus: i2s: Stop enabling I2S2 and I2S3 FIFOs

The driver never supported more than 2 channels because of
ep93xx_i2s_dma_data[] supporting only 1 DMA channel in each
direction.
Stop enabling two unused I2S controller FIFOs, this will simplify
future interrupt support.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 sound/soc/cirrus/ep93xx-i2s.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/sound/soc/cirrus/ep93xx-i2s.c b/sound/soc/cirrus/ep93xx-i2s.c
index 0dc3852c4621..42cc6d22baac 100644
--- a/sound/soc/cirrus/ep93xx-i2s.c
+++ b/sound/soc/cirrus/ep93xx-i2s.c
@@ -98,7 +98,6 @@ static inline unsigned ep93xx_i2s_read_reg(struct ep93xx_i2s_info *info,
 static void ep93xx_i2s_enable(struct ep93xx_i2s_info *info, int stream)
 {
 	unsigned base_reg;
-	int i;
 
 	if ((ep93xx_i2s_read_reg(info, EP93XX_I2S_TX0EN) & 0x1) == 0 &&
 	    (ep93xx_i2s_read_reg(info, EP93XX_I2S_RX0EN) & 0x1) == 0) {
@@ -111,27 +110,24 @@ static void ep93xx_i2s_enable(struct ep93xx_i2s_info *info, int stream)
 		ep93xx_i2s_write_reg(info, EP93XX_I2S_GLCTRL, 1);
 	}
 
-	/* Enable fifos */
+	/* Enable fifo */
 	if (stream == SNDRV_PCM_STREAM_PLAYBACK)
 		base_reg = EP93XX_I2S_TX0EN;
 	else
 		base_reg = EP93XX_I2S_RX0EN;
-	for (i = 0; i < 3; i++)
-		ep93xx_i2s_write_reg(info, base_reg + (i * 4), 1);
+	ep93xx_i2s_write_reg(info, base_reg, 1);
 }
 
 static void ep93xx_i2s_disable(struct ep93xx_i2s_info *info, int stream)
 {
 	unsigned base_reg;
-	int i;
 
-	/* Disable fifos */
+	/* Disable fifo */
 	if (stream == SNDRV_PCM_STREAM_PLAYBACK)
 		base_reg = EP93XX_I2S_TX0EN;
 	else
 		base_reg = EP93XX_I2S_RX0EN;
-	for (i = 0; i < 3; i++)
-		ep93xx_i2s_write_reg(info, base_reg + (i * 4), 0);
+	ep93xx_i2s_write_reg(info, base_reg, 0);
 
 	if ((ep93xx_i2s_read_reg(info, EP93XX_I2S_TX0EN) & 0x1) == 0 &&
 	    (ep93xx_i2s_read_reg(info, EP93XX_I2S_RX0EN) & 0x1) == 0) {
-- 
2.17.0

[PATCH 4/5] ARM: ep93xx: i2s: Add IRQ to platform device resources

[Alexander Sverdlin]

According to "EP93xx User?s Guide" it's called I2SINTR and has number 60.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
---
 arch/arm/mach-ep93xx/core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/mach-ep93xx/core.c b/arch/arm/mach-ep93xx/core.c
index e70feec6fad5..48d6a9e01dc8 100644
--- a/arch/arm/mach-ep93xx/core.c
+++ b/arch/arm/mach-ep93xx/core.c
@@ -635,6 +635,7 @@ EXPORT_SYMBOL(ep93xx_keypad_release_gpio);
  *************************************************************************/
 static struct resource ep93xx_i2s_resource[] = {
 	DEFINE_RES_MEM(EP93XX_I2S_PHYS_BASE, 0x100),
+	DEFINE_RES_IRQ(IRQ_EP93XX_SAI),
 };
 
 static struct platform_device ep93xx_i2s_device = {
-- 
2.16.2

Applied "ARM: ep93xx: i2s: Add IRQ to platform device resources" to the asoc tree

[Mark Brown]

The patch

   ARM: ep93xx: i2s: Add IRQ to platform device resources

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 6ea8a84806ac91809e1759a200bf3c272b12aeb9 Mon Sep 17 00:00:00 2001
From: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Date: Sat, 28 Apr 2018 22:51:41 +0200
Subject: [PATCH] ARM: ep93xx: i2s: Add IRQ to platform device resources
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

According to "EP93xx User???s Guide" it's called I2SINTR and has number 60.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 arch/arm/mach-ep93xx/core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/mach-ep93xx/core.c b/arch/arm/mach-ep93xx/core.c
index e70feec6fad5..48d6a9e01dc8 100644
--- a/arch/arm/mach-ep93xx/core.c
+++ b/arch/arm/mach-ep93xx/core.c
@@ -635,6 +635,7 @@ EXPORT_SYMBOL(ep93xx_keypad_release_gpio);
  *************************************************************************/
 static struct resource ep93xx_i2s_resource[] = {
 	DEFINE_RES_MEM(EP93XX_I2S_PHYS_BASE, 0x100),
+	DEFINE_RES_IRQ(IRQ_EP93XX_SAI),
 };
 
 static struct platform_device ep93xx_i2s_device = {
-- 
2.17.0

[PATCH 5/5] ASoC: cirrus: i2s: IRQ-based stream watchdog

[Alexander Sverdlin]

I2S controller on EP93xx seems to have undocumented HW issue. According to
"EP93xx User?s Guide", controller can handle underflow and either transmit
last sample or zeroes in such case until FIFO is filled again. In reality
undeflow conditions seem to confuse internal state machine from time to
time and the whole stream gets shifted by one byte (as captured by logic
analyser on the I2S outputs). One could only hear noise instead of original
stream and this continues until the FIFO is disabled and enabled again.

Work this around by watching underflow interrupt and resetting I2S TX
channel + fill FIFO with zero samples until DMA catches up again. This is
a nasty workaround, but it works. Hence, Kconfig option to disable it in
case of problems.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
---
 sound/soc/cirrus/Kconfig      | 17 +++++++++++
 sound/soc/cirrus/ep93xx-i2s.c | 68 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 85 insertions(+)

diff --git a/sound/soc/cirrus/Kconfig b/sound/soc/cirrus/Kconfig
index c7cd60f009e9..e09199124c36 100644
--- a/sound/soc/cirrus/Kconfig
+++ b/sound/soc/cirrus/Kconfig
@@ -9,6 +9,23 @@ config SND_EP93XX_SOC
 config SND_EP93XX_SOC_I2S
 	tristate
 
+if SND_EP93XX_SOC_I2S
+
+config SND_EP93XX_SOC_I2S_WATCHDOG
+	bool "IRQ based underflow watchdog workaround"
+	default y
+	help
+	  I2S controller on EP93xx seems to have undocumented HW issue.
+	  Underflow of internal I2S controller FIFO could confuse the
+	  state machine and the whole stream can be shifted by one byte
+	  until I2S is disabled. This option enables IRQ based watchdog
+	  which disables and re-enables I2S in case of underflow and
+	  fills FIFO with zeroes.
+
+	  If you are unsure how to answer this question, answer Y.
+
+endif # if SND_EP93XX_SOC_I2S
+
 config SND_EP93XX_SOC_AC97
 	tristate
 	select AC97_BUS
diff --git a/sound/soc/cirrus/ep93xx-i2s.c b/sound/soc/cirrus/ep93xx-i2s.c
index 42cc6d22baac..0918c5da575a 100644
--- a/sound/soc/cirrus/ep93xx-i2s.c
+++ b/sound/soc/cirrus/ep93xx-i2s.c
@@ -35,8 +35,12 @@
 
 #define EP93XX_I2S_TXCLKCFG		0x00
 #define EP93XX_I2S_RXCLKCFG		0x04
+#define EP93XX_I2S_GLSTS		0x08
 #define EP93XX_I2S_GLCTRL		0x0C
 
+#define EP93XX_I2S_I2STX0LFT		0x10
+#define EP93XX_I2S_I2STX0RT		0x14
+
 #define EP93XX_I2S_TXLINCTRLDATA	0x28
 #define EP93XX_I2S_TXCTRL		0x2C
 #define EP93XX_I2S_TXWRDLEN		0x30
@@ -55,12 +59,22 @@
 
 #define EP93XX_I2S_TXLINCTRLDATA_R_JUST	BIT(2) /* Right justify */
 
+/*
+ * Transmit empty interrupt level select:
+ * 0 - Generate interrupt when FIFO is half empty
+ * 1 - Generate interrupt when FIFO is empty
+ */
+#define EP93XX_I2S_TXCTRL_TXEMPTY_LVL	BIT(0)
+#define EP93XX_I2S_TXCTRL_TXUFIE	BIT(1) /* Transmit interrupt enable */
+
 #define EP93XX_I2S_CLKCFG_LRS		(1 << 0) /* lrclk polarity */
 #define EP93XX_I2S_CLKCFG_CKP		(1 << 1) /* Bit clock polarity */
 #define EP93XX_I2S_CLKCFG_REL		(1 << 2) /* First bit transition */
 #define EP93XX_I2S_CLKCFG_MASTER	(1 << 3) /* Master mode */
 #define EP93XX_I2S_CLKCFG_NBCG		(1 << 4) /* Not bit clock gating */
 
+#define EP93XX_I2S_GLSTS_TX0_FIFO_FULL	BIT(12)
+
 struct ep93xx_i2s_info {
 	struct clk			*mclk;
 	struct clk			*sclk;
@@ -116,12 +130,24 @@ static void ep93xx_i2s_enable(struct ep93xx_i2s_info *info, int stream)
 	else
 		base_reg = EP93XX_I2S_RX0EN;
 	ep93xx_i2s_write_reg(info, base_reg, 1);
+
+	/* Enable TX IRQs (FIFO empty or underflow) */
+	if (IS_ENABLED(CONFIG_SND_EP93XX_SOC_I2S_WATCHDOG) &&
+	    stream == SNDRV_PCM_STREAM_PLAYBACK)
+		ep93xx_i2s_write_reg(info, EP93XX_I2S_TXCTRL,
+				     EP93XX_I2S_TXCTRL_TXEMPTY_LVL |
+				     EP93XX_I2S_TXCTRL_TXUFIE);
 }
 
 static void ep93xx_i2s_disable(struct ep93xx_i2s_info *info, int stream)
 {
 	unsigned base_reg;
 
+	/* Disable IRQs */
+	if (IS_ENABLED(CONFIG_SND_EP93XX_SOC_I2S_WATCHDOG) &&
+	    stream == SNDRV_PCM_STREAM_PLAYBACK)
+		ep93xx_i2s_write_reg(info, EP93XX_I2S_TXCTRL, 0);
+
 	/* Disable fifo */
 	if (stream == SNDRV_PCM_STREAM_PLAYBACK)
 		base_reg = EP93XX_I2S_TX0EN;
@@ -141,6 +167,37 @@ static void ep93xx_i2s_disable(struct ep93xx_i2s_info *info, int stream)
 	}
 }
 
+/*
+ * According to documentation I2S controller can handle underflow conditions
+ * just fine, but in reality the state machine is sometimes confused so that
+ * the whole stream is shifted by one byte. The watchdog below disables the TX
+ * FIFO, fills the buffer with zeroes and re-enables the FIFO. State machine
+ * is being reset and by filling the buffer we get some time before next
+ * underflow happens.
+ */
+static irqreturn_t ep93xx_i2s_interrupt(int irq, void *dev_id)
+{
+	struct ep93xx_i2s_info *info = dev_id;
+
+	/* Disable FIFO */
+	ep93xx_i2s_write_reg(info, EP93XX_I2S_TX0EN, 0);
+	/*
+	 * Fill TX FIFO with zeroes, this way we can defer next IRQs as much as
+	 * possible and get more time for DMA to catch up. Actually there are
+	 * only 8 samples in this FIFO, so even on 8kHz maximum deferral here is
+	 * 1ms.
+	 */
+	while (!(ep93xx_i2s_read_reg(info, EP93XX_I2S_GLSTS) &
+		 EP93XX_I2S_GLSTS_TX0_FIFO_FULL)) {
+		ep93xx_i2s_write_reg(info, EP93XX_I2S_I2STX0LFT, 0);
+		ep93xx_i2s_write_reg(info, EP93XX_I2S_I2STX0RT, 0);
+	}
+	/* Re-enable FIFO */
+	ep93xx_i2s_write_reg(info, EP93XX_I2S_TX0EN, 1);
+
+	return IRQ_HANDLED;
+}
+
 static int ep93xx_i2s_dai_probe(struct snd_soc_dai *dai)
 {
 	struct ep93xx_i2s_info *info = snd_soc_dai_get_drvdata(dai);
@@ -390,6 +447,17 @@ static int ep93xx_i2s_probe(struct platform_device *pdev)
 	if (IS_ERR(info->regs))
 		return PTR_ERR(info->regs);
 
+	if (IS_ENABLED(CONFIG_SND_EP93XX_SOC_I2S_WATCHDOG)) {
+		int irq = platform_get_irq(pdev, 0);
+		if (irq <= 0)
+			return irq < 0 ? irq : -ENODEV;
+
+		err = devm_request_irq(&pdev->dev, irq, ep93xx_i2s_interrupt, 0,
+				       pdev->name, info);
+		if (err)
+			return err;
+	}
+
 	info->mclk = clk_get(&pdev->dev, "mclk");
 	if (IS_ERR(info->mclk)) {
 		err = PTR_ERR(info->mclk);
-- 
2.16.2

Applied "ASoC: cirrus: i2s: IRQ-based stream watchdog" to the asoc tree

[Mark Brown]

The patch

   ASoC: cirrus: i2s: IRQ-based stream watchdog

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 98e1241c357b82e070294f486cef91a1263874fa Mon Sep 17 00:00:00 2001
From: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Date: Sat, 28 Apr 2018 22:51:42 +0200
Subject: [PATCH] ASoC: cirrus: i2s: IRQ-based stream watchdog
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

I2S controller on EP93xx seems to have undocumented HW issue. According to
"EP93xx User???s Guide", controller can handle underflow and either transmit
last sample or zeroes in such case until FIFO is filled again. In reality
undeflow conditions seem to confuse internal state machine from time to
time and the whole stream gets shifted by one byte (as captured by logic
analyser on the I2S outputs). One could only hear noise instead of original
stream and this continues until the FIFO is disabled and enabled again.

Work this around by watching underflow interrupt and resetting I2S TX
channel + fill FIFO with zero samples until DMA catches up again. This is
a nasty workaround, but it works. Hence, Kconfig option to disable it in
case of problems.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 sound/soc/cirrus/Kconfig      | 17 +++++++++
 sound/soc/cirrus/ep93xx-i2s.c | 68 +++++++++++++++++++++++++++++++++++
 2 files changed, 85 insertions(+)

diff --git a/sound/soc/cirrus/Kconfig b/sound/soc/cirrus/Kconfig
index c7cd60f009e9..e09199124c36 100644
--- a/sound/soc/cirrus/Kconfig
+++ b/sound/soc/cirrus/Kconfig
@@ -9,6 +9,23 @@ config SND_EP93XX_SOC
 config SND_EP93XX_SOC_I2S
 	tristate
 
+if SND_EP93XX_SOC_I2S
+
+config SND_EP93XX_SOC_I2S_WATCHDOG
+	bool "IRQ based underflow watchdog workaround"
+	default y
+	help
+	  I2S controller on EP93xx seems to have undocumented HW issue.
+	  Underflow of internal I2S controller FIFO could confuse the
+	  state machine and the whole stream can be shifted by one byte
+	  until I2S is disabled. This option enables IRQ based watchdog
+	  which disables and re-enables I2S in case of underflow and
+	  fills FIFO with zeroes.
+
+	  If you are unsure how to answer this question, answer Y.
+
+endif # if SND_EP93XX_SOC_I2S
+
 config SND_EP93XX_SOC_AC97
 	tristate
 	select AC97_BUS
diff --git a/sound/soc/cirrus/ep93xx-i2s.c b/sound/soc/cirrus/ep93xx-i2s.c
index 42cc6d22baac..0918c5da575a 100644
--- a/sound/soc/cirrus/ep93xx-i2s.c
+++ b/sound/soc/cirrus/ep93xx-i2s.c
@@ -35,8 +35,12 @@
 
 #define EP93XX_I2S_TXCLKCFG		0x00
 #define EP93XX_I2S_RXCLKCFG		0x04
+#define EP93XX_I2S_GLSTS		0x08
 #define EP93XX_I2S_GLCTRL		0x0C
 
+#define EP93XX_I2S_I2STX0LFT		0x10
+#define EP93XX_I2S_I2STX0RT		0x14
+
 #define EP93XX_I2S_TXLINCTRLDATA	0x28
 #define EP93XX_I2S_TXCTRL		0x2C
 #define EP93XX_I2S_TXWRDLEN		0x30
@@ -55,12 +59,22 @@
 
 #define EP93XX_I2S_TXLINCTRLDATA_R_JUST	BIT(2) /* Right justify */
 
+/*
+ * Transmit empty interrupt level select:
+ * 0 - Generate interrupt when FIFO is half empty
+ * 1 - Generate interrupt when FIFO is empty
+ */
+#define EP93XX_I2S_TXCTRL_TXEMPTY_LVL	BIT(0)
+#define EP93XX_I2S_TXCTRL_TXUFIE	BIT(1) /* Transmit interrupt enable */
+
 #define EP93XX_I2S_CLKCFG_LRS		(1 << 0) /* lrclk polarity */
 #define EP93XX_I2S_CLKCFG_CKP		(1 << 1) /* Bit clock polarity */
 #define EP93XX_I2S_CLKCFG_REL		(1 << 2) /* First bit transition */
 #define EP93XX_I2S_CLKCFG_MASTER	(1 << 3) /* Master mode */
 #define EP93XX_I2S_CLKCFG_NBCG		(1 << 4) /* Not bit clock gating */
 
+#define EP93XX_I2S_GLSTS_TX0_FIFO_FULL	BIT(12)
+
 struct ep93xx_i2s_info {
 	struct clk			*mclk;
 	struct clk			*sclk;
@@ -116,12 +130,24 @@ static void ep93xx_i2s_enable(struct ep93xx_i2s_info *info, int stream)
 	else
 		base_reg = EP93XX_I2S_RX0EN;
 	ep93xx_i2s_write_reg(info, base_reg, 1);
+
+	/* Enable TX IRQs (FIFO empty or underflow) */
+	if (IS_ENABLED(CONFIG_SND_EP93XX_SOC_I2S_WATCHDOG) &&
+	    stream == SNDRV_PCM_STREAM_PLAYBACK)
+		ep93xx_i2s_write_reg(info, EP93XX_I2S_TXCTRL,
+				     EP93XX_I2S_TXCTRL_TXEMPTY_LVL |
+				     EP93XX_I2S_TXCTRL_TXUFIE);
 }
 
 static void ep93xx_i2s_disable(struct ep93xx_i2s_info *info, int stream)
 {
 	unsigned base_reg;
 
+	/* Disable IRQs */
+	if (IS_ENABLED(CONFIG_SND_EP93XX_SOC_I2S_WATCHDOG) &&
+	    stream == SNDRV_PCM_STREAM_PLAYBACK)
+		ep93xx_i2s_write_reg(info, EP93XX_I2S_TXCTRL, 0);
+
 	/* Disable fifo */
 	if (stream == SNDRV_PCM_STREAM_PLAYBACK)
 		base_reg = EP93XX_I2S_TX0EN;
@@ -141,6 +167,37 @@ static void ep93xx_i2s_disable(struct ep93xx_i2s_info *info, int stream)
 	}
 }
 
+/*
+ * According to documentation I2S controller can handle underflow conditions
+ * just fine, but in reality the state machine is sometimes confused so that
+ * the whole stream is shifted by one byte. The watchdog below disables the TX
+ * FIFO, fills the buffer with zeroes and re-enables the FIFO. State machine
+ * is being reset and by filling the buffer we get some time before next
+ * underflow happens.
+ */
+static irqreturn_t ep93xx_i2s_interrupt(int irq, void *dev_id)
+{
+	struct ep93xx_i2s_info *info = dev_id;
+
+	/* Disable FIFO */
+	ep93xx_i2s_write_reg(info, EP93XX_I2S_TX0EN, 0);
+	/*
+	 * Fill TX FIFO with zeroes, this way we can defer next IRQs as much as
+	 * possible and get more time for DMA to catch up. Actually there are
+	 * only 8 samples in this FIFO, so even on 8kHz maximum deferral here is
+	 * 1ms.
+	 */
+	while (!(ep93xx_i2s_read_reg(info, EP93XX_I2S_GLSTS) &
+		 EP93XX_I2S_GLSTS_TX0_FIFO_FULL)) {
+		ep93xx_i2s_write_reg(info, EP93XX_I2S_I2STX0LFT, 0);
+		ep93xx_i2s_write_reg(info, EP93XX_I2S_I2STX0RT, 0);
+	}
+	/* Re-enable FIFO */
+	ep93xx_i2s_write_reg(info, EP93XX_I2S_TX0EN, 1);
+
+	return IRQ_HANDLED;
+}
+
 static int ep93xx_i2s_dai_probe(struct snd_soc_dai *dai)
 {
 	struct ep93xx_i2s_info *info = snd_soc_dai_get_drvdata(dai);
@@ -390,6 +447,17 @@ static int ep93xx_i2s_probe(struct platform_device *pdev)
 	if (IS_ERR(info->regs))
 		return PTR_ERR(info->regs);
 
+	if (IS_ENABLED(CONFIG_SND_EP93XX_SOC_I2S_WATCHDOG)) {
+		int irq = platform_get_irq(pdev, 0);
+		if (irq <= 0)
+			return irq < 0 ? irq : -ENODEV;
+
+		err = devm_request_irq(&pdev->dev, irq, ep93xx_i2s_interrupt, 0,
+				       pdev->name, info);
+		if (err)
+			return err;
+	}
+
 	info->mclk = clk_get(&pdev->dev, "mclk");
 	if (IS_ERR(info->mclk)) {
 		err = PTR_ERR(info->mclk);
-- 
2.17.0