[PATCH v3 0/3] refine and clean code for synchronous mode

[PATCH v3 0/3] refine and clean code for synchronous mode

[Shengjiu Wang]

refine and clean code for synchronous mode

Shengjiu Wang (3):
  ASoC: fsl_sai: Refine enable/disable TE/RE sequence in trigger()
  ASoC: fsl_sai: Drop TMR/RMR settings for synchronous mode
  ASoC: fsl_sai: Replace synchronous check with fsl_sai_dir_is_synced

changes in v3:
- Add reviewed-by Nicolin
- refine the commit log.
- Add one more patch #3

changes in v2:
- Split the commit
- refine the sequence in trigger stop

 sound/soc/fsl/fsl_sai.c | 173 +++++++++++++++++++++++-----------------
 1 file changed, 102 insertions(+), 71 deletions(-)

-- 
2.27.0

[PATCH v3 1/3] ASoC: fsl_sai: Refine enable/disable TE/RE sequence in trigger()

[Shengjiu Wang]

Current code enables TCSR.TE and RCSR.RE together, and disable
TCSR.TE and RCSR.RE together in trigger(), which only supports
one operation mode：
1. Rx synchronous with Tx: TE is last enabled and first disabled

Other operation mode need to be considered also:
2. Tx synchronous with Rx: RE is last enabled and first disabled.
3. Asynchronous mode: Tx and Rx are independent.

So the enable TCSR.TE and RCSR.RE sequence and the disable
sequence need to be refined accordingly for #2 and #3.

There is slightly against what RM recommennds with this change.
For example in Rx synchronous with Tx mode, case "aplay 1.wav;
arecord 2.wav" enable TE before RE. But it should be safe to
do so, judging by years of testing results.

Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Reviewed-by: Nicolin Chen <nicoleotsuka@gmail.com>
---
 sound/soc/fsl/fsl_sai.c | 126 +++++++++++++++++++++++++++-------------
 1 file changed, 85 insertions(+), 41 deletions(-)

diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
index cdff739924e2..566c4747362a 100644
--- a/sound/soc/fsl/fsl_sai.c
+++ b/sound/soc/fsl/fsl_sai.c
@@ -37,6 +37,24 @@ static const struct snd_pcm_hw_constraint_list fsl_sai_rate_constraints = {
 	.list = fsl_sai_rates,
 };
 
+/**
+ * fsl_sai_dir_is_synced - Check if stream is synced by the opposite stream
+ *
+ * SAI supports synchronous mode using bit/frame clocks of either Transmitter's
+ * or Receiver's for both streams. This function is used to check if clocks of
+ * the stream's are synced by the opposite stream.
+ *
+ * @sai: SAI context
+ * @dir: stream direction
+ */
+static inline bool fsl_sai_dir_is_synced(struct fsl_sai *sai, int dir)
+{
+	int adir = (dir == TX) ? RX : TX;
+
+	/* current dir in async mode while opposite dir in sync mode */
+	return !sai->synchronous[dir] && sai->synchronous[adir];
+}
+
 static irqreturn_t fsl_sai_isr(int irq, void *devid)
 {
 	struct fsl_sai *sai = (struct fsl_sai *)devid;
@@ -522,6 +540,38 @@ static int fsl_sai_hw_free(struct snd_pcm_substream *substream,
 	return 0;
 }
 
+static void fsl_sai_config_disable(struct fsl_sai *sai, int dir)
+{
+	unsigned int ofs = sai->soc_data->reg_offset;
+	bool tx = dir == TX;
+	u32 xcsr, count = 100;
+
+	regmap_update_bits(sai->regmap, FSL_SAI_xCSR(tx, ofs),
+			   FSL_SAI_CSR_TERE, 0);
+
+	/* TERE will remain set till the end of current frame */
+	do {
+		udelay(10);
+		regmap_read(sai->regmap, FSL_SAI_xCSR(tx, ofs), &xcsr);
+	} while (--count && xcsr & FSL_SAI_CSR_TERE);
+
+	regmap_update_bits(sai->regmap, FSL_SAI_xCSR(tx, ofs),
+			   FSL_SAI_CSR_FR, FSL_SAI_CSR_FR);
+
+	/*
+	 * For sai master mode, after several open/close sai,
+	 * there will be no frame clock, and can't recover
+	 * anymore. Add software reset to fix this issue.
+	 * This is a hardware bug, and will be fix in the
+	 * next sai version.
+	 */
+	if (!sai->is_slave_mode) {
+		/* Software Reset */
+		regmap_write(sai->regmap, FSL_SAI_xCSR(tx, ofs), FSL_SAI_CSR_SR);
+		/* Clear SR bit to finish the reset */
+		regmap_write(sai->regmap, FSL_SAI_xCSR(tx, ofs), 0);
+	}
+}
 
 static int fsl_sai_trigger(struct snd_pcm_substream *substream, int cmd,
 		struct snd_soc_dai *cpu_dai)
@@ -530,7 +580,9 @@ static int fsl_sai_trigger(struct snd_pcm_substream *substream, int cmd,
 	unsigned int ofs = sai->soc_data->reg_offset;
 
 	bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
-	u32 xcsr, count = 100;
+	int adir = tx ? RX : TX;
+	int dir = tx ? TX : RX;
+	u32 xcsr;
 
 	/*
 	 * Asynchronous mode: Clear SYNC for both Tx and Rx.
@@ -553,10 +605,22 @@ static int fsl_sai_trigger(struct snd_pcm_substream *substream, int cmd,
 		regmap_update_bits(sai->regmap, FSL_SAI_xCSR(tx, ofs),
 				   FSL_SAI_CSR_FRDE, FSL_SAI_CSR_FRDE);
 
-		regmap_update_bits(sai->regmap, FSL_SAI_RCSR(ofs),
-				   FSL_SAI_CSR_TERE, FSL_SAI_CSR_TERE);
-		regmap_update_bits(sai->regmap, FSL_SAI_TCSR(ofs),
+		regmap_update_bits(sai->regmap, FSL_SAI_xCSR(tx, ofs),
 				   FSL_SAI_CSR_TERE, FSL_SAI_CSR_TERE);
+		/*
+		 * Enable the opposite direction for synchronous mode
+		 * 1. Tx sync with Rx: only set RE for Rx; set TE & RE for Tx
+		 * 2. Rx sync with Tx: only set TE for Tx; set RE & TE for Rx
+		 *
+		 * RM recommends to enable RE after TE for case 1 and to enable
+		 * TE after RE for case 2, but we here may not always guarantee
+		 * that happens: "arecord 1.wav; aplay 2.wav" in case 1 enables
+		 * TE after RE, which is against what RM recommends but should
+		 * be safe to do, judging by years of testing results.
+		 */
+		if (fsl_sai_dir_is_synced(sai, adir))
+			regmap_update_bits(sai->regmap, FSL_SAI_xCSR((!tx), ofs),
+					   FSL_SAI_CSR_TERE, FSL_SAI_CSR_TERE);
 
 		regmap_update_bits(sai->regmap, FSL_SAI_xCSR(tx, ofs),
 				   FSL_SAI_CSR_xIE_MASK, FSL_SAI_FLAGS);
@@ -571,43 +635,23 @@ static int fsl_sai_trigger(struct snd_pcm_substream *substream, int cmd,
 
 		/* Check if the opposite FRDE is also disabled */
 		regmap_read(sai->regmap, FSL_SAI_xCSR(!tx, ofs), &xcsr);
-		if (!(xcsr & FSL_SAI_CSR_FRDE)) {
-			/* Disable both directions and reset their FIFOs */
-			regmap_update_bits(sai->regmap, FSL_SAI_TCSR(ofs),
-					   FSL_SAI_CSR_TERE, 0);
-			regmap_update_bits(sai->regmap, FSL_SAI_RCSR(ofs),
-					   FSL_SAI_CSR_TERE, 0);
-
-			/* TERE will remain set till the end of current frame */
-			do {
-				udelay(10);
-				regmap_read(sai->regmap,
-					    FSL_SAI_xCSR(tx, ofs), &xcsr);
-			} while (--count && xcsr & FSL_SAI_CSR_TERE);
-
-			regmap_update_bits(sai->regmap, FSL_SAI_TCSR(ofs),
-					   FSL_SAI_CSR_FR, FSL_SAI_CSR_FR);
-			regmap_update_bits(sai->regmap, FSL_SAI_RCSR(ofs),
-					   FSL_SAI_CSR_FR, FSL_SAI_CSR_FR);
-
-			/*
-			 * For sai master mode, after several open/close sai,
-			 * there will be no frame clock, and can't recover
-			 * anymore. Add software reset to fix this issue.
-			 * This is a hardware bug, and will be fix in the
-			 * next sai version.
-			 */
-			if (!sai->is_slave_mode) {
-				/* Software Reset for both Tx and Rx */
-				regmap_write(sai->regmap, FSL_SAI_TCSR(ofs),
-					     FSL_SAI_CSR_SR);
-				regmap_write(sai->regmap, FSL_SAI_RCSR(ofs),
-					     FSL_SAI_CSR_SR);
-				/* Clear SR bit to finish the reset */
-				regmap_write(sai->regmap, FSL_SAI_TCSR(ofs), 0);
-				regmap_write(sai->regmap, FSL_SAI_RCSR(ofs), 0);
-			}
-		}
+
+		/*
+		 * If opposite stream provides clocks for synchronous mode and
+		 * it is inactive, disable it before disabling the current one
+		 */
+		if (fsl_sai_dir_is_synced(sai, adir) && !(xcsr & FSL_SAI_CSR_FRDE))
+			fsl_sai_config_disable(sai, adir);
+
+		/*
+		 * Disable current stream if either of:
+		 * 1. current stream doesn't provide clocks for synchronous mode
+		 * 2. current stream provides clocks for synchronous mode but no
+		 *    more stream is active.
+		 */
+		if (!fsl_sai_dir_is_synced(sai, dir) || !(xcsr & FSL_SAI_CSR_FRDE))
+			fsl_sai_config_disable(sai, dir);
+
 		break;
 	default:
 		return -EINVAL;
-- 
2.27.0

[PATCH v3 2/3] ASoC: fsl_sai: Drop TMR/RMR settings for synchronous mode

[Shengjiu Wang]

Tx synchronous with Rx: The RMR is the word mask register, it is used
to mask any word in the frame, it is not relating to clock generation,
So it is no need to be changed when Tx is going to be enabled.

Rx synchronous with Tx: The TMR is the word mask register, it is used
to mask any word in the frame, it is not relating to clock generation,
So it is no need to be changed when Rx is going to be enabled.

Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Reviewed-by: Nicolin Chen <nicoleotsuka@gmail.com>
---
 sound/soc/fsl/fsl_sai.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
index 566c4747362a..334090d581ae 100644
--- a/sound/soc/fsl/fsl_sai.c
+++ b/sound/soc/fsl/fsl_sai.c
@@ -488,8 +488,7 @@ static int fsl_sai_hw_params(struct snd_pcm_substream *substream,
 	/*
 	 * For SAI master mode, when Tx(Rx) sync with Rx(Tx) clock, Rx(Tx) will
 	 * generate bclk and frame clock for Tx(Rx), we should set RCR4(TCR4),
-	 * RCR5(TCR5) and RMR(TMR) for playback(capture), or there will be sync
-	 * error.
+	 * RCR5(TCR5) for playback(capture), or there will be sync error.
 	 */
 
 	if (!sai->is_slave_mode) {
@@ -500,8 +499,6 @@ static int fsl_sai_hw_params(struct snd_pcm_substream *substream,
 			regmap_update_bits(sai->regmap, FSL_SAI_TCR5(ofs),
 				FSL_SAI_CR5_WNW_MASK | FSL_SAI_CR5_W0W_MASK |
 				FSL_SAI_CR5_FBT_MASK, val_cr5);
-			regmap_write(sai->regmap, FSL_SAI_TMR,
-				~0UL - ((1 << channels) - 1));
 		} else if (!sai->synchronous[RX] && sai->synchronous[TX] && tx) {
 			regmap_update_bits(sai->regmap, FSL_SAI_RCR4(ofs),
 				FSL_SAI_CR4_SYWD_MASK | FSL_SAI_CR4_FRSZ_MASK,
@@ -509,8 +506,6 @@ static int fsl_sai_hw_params(struct snd_pcm_substream *substream,
 			regmap_update_bits(sai->regmap, FSL_SAI_RCR5(ofs),
 				FSL_SAI_CR5_WNW_MASK | FSL_SAI_CR5_W0W_MASK |
 				FSL_SAI_CR5_FBT_MASK, val_cr5);
-			regmap_write(sai->regmap, FSL_SAI_RMR,
-				~0UL - ((1 << channels) - 1));
 		}
 	}
 
-- 
2.27.0

[PATCH v3 3/3] ASoC: fsl_sai: Replace synchronous check with fsl_sai_dir_is_synced

[Shengjiu Wang]

As new function fsl_sai_dir_is_synced is included for checking if
stream is synced by the opposite stream, then replace the existing
synchronous checking with this new function.

Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
---
 sound/soc/fsl/fsl_sai.c | 40 ++++++++++++++++------------------------
 1 file changed, 16 insertions(+), 24 deletions(-)

diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
index 334090d581ae..f6969a5d49e3 100644
--- a/sound/soc/fsl/fsl_sai.c
+++ b/sound/soc/fsl/fsl_sai.c
@@ -350,6 +350,8 @@ static int fsl_sai_set_bclk(struct snd_soc_dai *dai, bool tx, u32 freq)
 	unsigned int ofs = sai->soc_data->reg_offset;
 	unsigned long clk_rate;
 	u32 savediv = 0, ratio, savesub = freq;
+	int adir = tx ? RX : TX;
+	int dir = tx ? TX : RX;
 	u32 id;
 	int ret = 0;
 
@@ -408,19 +410,17 @@ static int fsl_sai_set_bclk(struct snd_soc_dai *dai, bool tx, u32 freq)
 	 * 4) For Tx and Rx are both Synchronous with another SAI, we just
 	 *    ignore it.
 	 */
-	if ((sai->synchronous[TX] && !sai->synchronous[RX]) ||
-	    (!tx && !sai->synchronous[RX])) {
-		regmap_update_bits(sai->regmap, FSL_SAI_RCR2(ofs),
+	if (fsl_sai_dir_is_synced(sai, adir)) {
+		regmap_update_bits(sai->regmap, FSL_SAI_xCR2(!tx, ofs),
 				   FSL_SAI_CR2_MSEL_MASK,
 				   FSL_SAI_CR2_MSEL(sai->mclk_id[tx]));
-		regmap_update_bits(sai->regmap, FSL_SAI_RCR2(ofs),
+		regmap_update_bits(sai->regmap, FSL_SAI_xCR2(!tx, ofs),
 				   FSL_SAI_CR2_DIV_MASK, savediv - 1);
-	} else if ((sai->synchronous[RX] && !sai->synchronous[TX]) ||
-		   (tx && !sai->synchronous[TX])) {
-		regmap_update_bits(sai->regmap, FSL_SAI_TCR2(ofs),
+	} else if (!sai->synchronous[dir]) {
+		regmap_update_bits(sai->regmap, FSL_SAI_xCR2(tx, ofs),
 				   FSL_SAI_CR2_MSEL_MASK,
 				   FSL_SAI_CR2_MSEL(sai->mclk_id[tx]));
-		regmap_update_bits(sai->regmap, FSL_SAI_TCR2(ofs),
+		regmap_update_bits(sai->regmap, FSL_SAI_xCR2(tx, ofs),
 				   FSL_SAI_CR2_DIV_MASK, savediv - 1);
 	}
 
@@ -442,6 +442,7 @@ static int fsl_sai_hw_params(struct snd_pcm_substream *substream,
 	u32 val_cr4 = 0, val_cr5 = 0;
 	u32 slots = (channels == 1) ? 2 : channels;
 	u32 slot_width = word_width;
+	int adir = tx ? RX : TX;
 	int ret;
 
 	if (sai->slots)
@@ -491,22 +492,13 @@ static int fsl_sai_hw_params(struct snd_pcm_substream *substream,
 	 * RCR5(TCR5) for playback(capture), or there will be sync error.
 	 */
 
-	if (!sai->is_slave_mode) {
-		if (!sai->synchronous[TX] && sai->synchronous[RX] && !tx) {
-			regmap_update_bits(sai->regmap, FSL_SAI_TCR4(ofs),
-				FSL_SAI_CR4_SYWD_MASK | FSL_SAI_CR4_FRSZ_MASK,
-				val_cr4);
-			regmap_update_bits(sai->regmap, FSL_SAI_TCR5(ofs),
-				FSL_SAI_CR5_WNW_MASK | FSL_SAI_CR5_W0W_MASK |
-				FSL_SAI_CR5_FBT_MASK, val_cr5);
-		} else if (!sai->synchronous[RX] && sai->synchronous[TX] && tx) {
-			regmap_update_bits(sai->regmap, FSL_SAI_RCR4(ofs),
-				FSL_SAI_CR4_SYWD_MASK | FSL_SAI_CR4_FRSZ_MASK,
-				val_cr4);
-			regmap_update_bits(sai->regmap, FSL_SAI_RCR5(ofs),
-				FSL_SAI_CR5_WNW_MASK | FSL_SAI_CR5_W0W_MASK |
-				FSL_SAI_CR5_FBT_MASK, val_cr5);
-		}
+	if (!sai->is_slave_mode && fsl_sai_dir_is_synced(sai, adir)) {
+		regmap_update_bits(sai->regmap, FSL_SAI_xCR4(!tx, ofs),
+				   FSL_SAI_CR4_SYWD_MASK | FSL_SAI_CR4_FRSZ_MASK,
+				   val_cr4);
+		regmap_update_bits(sai->regmap, FSL_SAI_xCR5(!tx, ofs),
+				   FSL_SAI_CR5_WNW_MASK | FSL_SAI_CR5_W0W_MASK |
+				   FSL_SAI_CR5_FBT_MASK, val_cr5);
 	}
 
 	regmap_update_bits(sai->regmap, FSL_SAI_xCR4(tx, ofs),
-- 
2.27.0

Re: [PATCH v3 3/3] ASoC: fsl_sai: Replace synchronous check with fsl_sai_dir_is_synced

[Nicolin Chen]

On Wed, Aug 05, 2020 at 02:34:13PM +0800, Shengjiu Wang wrote:
> As new function fsl_sai_dir_is_synced is included for checking if
> stream is synced by the opposite stream, then replace the existing
> synchronous checking with this new function.
> 
> Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>

Acked-by: Nicolin Chen <nicoleotsuka@gmail.com>

Nice, thanks!

Re: [PATCH v3 0/3] refine and clean code for synchronous mode

[Mark Brown]

On Wed, 5 Aug 2020 14:34:10 +0800, Shengjiu Wang wrote:
> refine and clean code for synchronous mode
> 
> Shengjiu Wang (3):
>   ASoC: fsl_sai: Refine enable/disable TE/RE sequence in trigger()
>   ASoC: fsl_sai: Drop TMR/RMR settings for synchronous mode
>   ASoC: fsl_sai: Replace synchronous check with fsl_sai_dir_is_synced
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next

Thanks!

[1/3] ASoC: fsl_sai: Refine enable/disable TE/RE sequence in trigger()
      commit: 94741eba63c23b0f1527b0ae0125e6b553bde10e
[2/3] ASoC: fsl_sai: Drop TMR/RMR settings for synchronous mode
      commit: 7b3bee091ec375777ade2a37e4b0c9319f92de27
[3/3] ASoC: fsl_sai: Replace synchronous check with fsl_sai_dir_is_synced
      commit: 9355a7b1896f6fadcbd63d199d1f343bf2e4fed8

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