Merge series "refine and clean code for synchronous mode" from Shengjiu Wang <shengjiu.wang@nxp.com>:

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

Author: broonie

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;
@@ -332,6 +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;
 
@@ -390,19 +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);
 	}
 
@@ -424,6 +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)
@@ -470,30 +489,16 @@ 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) {
-		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);
-			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,
-				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);
-			regmap_write(sai->regmap, FSL_SAI_RMR,
-				~0UL - ((1 << channels) - 1));
-		}
+	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),
@@ -522,6 +527,38 @@ 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 +567,9 @@ 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 +592,22 @@ 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 +622,23 @@ 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;