[PATCH] ASoC: fsl_asrc: Add an option to select internal ratio mode

The ASRC not only supports ideal ratio mode, but also supports
internal ratio mode.

For internal rato mode, the rate of clock source should be divided
with no remainder by sample rate, otherwise there is sound
distortion.

Add function fsl_asrc_select_clk() to find proper clock source for
internal ratio mode, if the clock source is available then internal
ratio mode will be selected.

With change, the ideal ratio mode is not the only option for user.

Signed-off-by: Shengjiu Wang <redacted>
---
 sound/soc/fsl/fsl_asrc.c | 58 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 56 insertions(+), 2 deletions(-)

diff --git a/sound/soc/fsl/fsl_asrc.c b/sound/soc/fsl/fsl_asrc.c
index 95f6a9617b0b..fcafc8ecb131 100644
--- a/sound/soc/fsl/fsl_asrc.c
+++ b/sound/soc/fsl/fsl_asrc.c

@@ -582,11 +582,59 @@ static int fsl_asrc_dai_startup(struct snd_pcm_substream *substream,
 			SNDRV_PCM_HW_PARAM_RATE, &fsl_asrc_rate_constraints);
 }
 
+/**
+ * Select proper clock source for internal ratio mode
+ */
+static int fsl_asrc_select_clk(struct fsl_asrc_priv *asrc_priv,
+			       struct fsl_asrc_pair *pair,
+			       int in_rate,
+			       int out_rate)
+{
+	struct fsl_asrc_pair_priv *pair_priv = pair->private;
+	struct asrc_config *config = pair_priv->config;
+	int rate[2], select_clk[2]; /* Array size 2 means IN and OUT */
+	int clk_rate, clk_index;
+	int i = 0, j = 0;
+	bool clk_sel[2];
+
+	rate[0] = in_rate;
+	rate[1] = out_rate;
+
+	/* Select proper clock source for internal ratio mode */
+	for (j = 0; j < 2; j++) {
+		for (i = 0; i < ASRC_CLK_MAP_LEN; i++) {
+			clk_index = asrc_priv->clk_map[j][i];
+			clk_rate = clk_get_rate(asrc_priv->asrck_clk[clk_index]);
+			if (clk_rate != 0 && (clk_rate / rate[j]) <= 1024 &&
+			    (clk_rate % rate[j]) == 0)
+				break;
+		}
+
+		if (i == ASRC_CLK_MAP_LEN) {
+			select_clk[j] = OUTCLK_ASRCK1_CLK;
+			clk_sel[j] = false;
+		} else {
+			select_clk[j] = i;
+			clk_sel[j] = true;
+		}
+	}
+
+	/* Switch to ideal ratio mode if there is no proper clock source */
+	if (!clk_sel[IN] || !clk_sel[OUT])
+		select_clk[IN] = INCLK_NONE;
+
+	config->inclk = select_clk[IN];
+	config->outclk = select_clk[OUT];
+
+	return 0;
+}
+
 static int fsl_asrc_dai_hw_params(struct snd_pcm_substream *substream,
 				  struct snd_pcm_hw_params *params,
 				  struct snd_soc_dai *dai)
 {
 	struct fsl_asrc *asrc = snd_soc_dai_get_drvdata(dai);
+	struct fsl_asrc_priv *asrc_priv = asrc->private;
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct fsl_asrc_pair *pair = runtime->private_data;
 	struct fsl_asrc_pair_priv *pair_priv = pair->private;

@@ -605,8 +653,6 @@ static int fsl_asrc_dai_hw_params(struct snd_pcm_substream *substream,
 
 	config.pair = pair->index;
 	config.channel_num = channels;
-	config.inclk = INCLK_NONE;
-	config.outclk = OUTCLK_ASRCK1_CLK;
 
 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
 		config.input_format   = params_format(params);

@@ -620,6 +666,14 @@ static int fsl_asrc_dai_hw_params(struct snd_pcm_substream *substream,
 		config.output_sample_rate = rate;
 	}
 
+	ret = fsl_asrc_select_clk(asrc_priv, pair,
+				  config.input_sample_rate,
+				  config.output_sample_rate);
+	if (ret) {
+		dev_err(dai->dev, "fail to select clock\n");
+		return ret;
+	}
+
 	ret = fsl_asrc_config_pair(pair, false);
 	if (ret) {
 		dev_err(dai->dev, "fail to config asrc pair\n");

-- 
2.21.0

On Mon, Jun 29, 2020 at 09:58:35PM +0800, Shengjiu Wang wrote:

The ASRC not only supports ideal ratio mode, but also supports
internal ratio mode.

For internal rato mode, the rate of clock source should be divided
with no remainder by sample rate, otherwise there is sound
distortion.

Add function fsl_asrc_select_clk() to find proper clock source for
internal ratio mode, if the clock source is available then internal
ratio mode will be selected.

With change, the ideal ratio mode is not the only option for user.

Signed-off-by: Shengjiu Wang <redacted>
---

+static int fsl_asrc_select_clk(struct fsl_asrc_priv *asrc_priv,
+			       struct fsl_asrc_pair *pair,
+			       int in_rate,
+			       int out_rate)
+{
+	struct fsl_asrc_pair_priv *pair_priv = pair->private;
+	struct asrc_config *config = pair_priv->config;
+	int rate[2], select_clk[2]; /* Array size 2 means IN and OUT */
+	int clk_rate, clk_index;
+	int i = 0, j = 0;
+	bool clk_sel[2];
+
+	rate[0] = in_rate;
+	rate[1] = out_rate;
+
+	/* Select proper clock source for internal ratio mode */
+	for (j = 0; j < 2; j++) {
+		for (i = 0; i < ASRC_CLK_MAP_LEN; i++) {
+			clk_index = asrc_priv->clk_map[j][i];
+			clk_rate = clk_get_rate(asrc_priv->asrck_clk[clk_index]);

+			/* Only match a perfect clock source with no remainder */

+			if (clk_rate != 0 && (clk_rate / rate[j]) <= 1024 &&
+			    (clk_rate % rate[j]) == 0)
+				break;
+		}
+
+		if (i == ASRC_CLK_MAP_LEN) {
+			select_clk[j] = OUTCLK_ASRCK1_CLK;
+			clk_sel[j] = false;
+		} else {
+			select_clk[j] = i;
+			clk_sel[j] = true;
+		}
+	}
+
+	/* Switch to ideal ratio mode if there is no proper clock source */
+	if (!clk_sel[IN] || !clk_sel[OUT])
+		select_clk[IN] = INCLK_NONE;

Could get rid of clk_set:

	for (j) {
		for (i) {
			if (match)
				break;
		}

		clk[j] = i;
	}

	if (clk[IN] == ASRC_CLK_MAP_LEN || clk[OUT] == ASRC_CLK_MAP_LEN)

And it only overrides clk[IN] setting but leaving clk[OUT] to
to the searching result. This means that clk[OUT] may be using
a clock source other than OUTCLK_ASRCK1_CLK if sel[IN] happens
to be false while sel[OUT] happens to be true. Not sure if it
is intended...but I feel it would probably be safer to use the
previous settings: INCLK_NONE + OUTCLK_ASRCK1_CLK?

On Tue, Jun 30, 2020 at 4:09 AM Nicolin Chen [off-list ref] wrote:

On Mon, Jun 29, 2020 at 09:58:35PM +0800, Shengjiu Wang wrote:

quoted

The ASRC not only supports ideal ratio mode, but also supports
internal ratio mode.

For internal rato mode, the rate of clock source should be divided
with no remainder by sample rate, otherwise there is sound
distortion.

Add function fsl_asrc_select_clk() to find proper clock source for
internal ratio mode, if the clock source is available then internal
ratio mode will be selected.

With change, the ideal ratio mode is not the only option for user.

Signed-off-by: Shengjiu Wang <redacted>
---

quoted

+static int fsl_asrc_select_clk(struct fsl_asrc_priv *asrc_priv,
+                            struct fsl_asrc_pair *pair,
+                            int in_rate,
+                            int out_rate)
+{
+     struct fsl_asrc_pair_priv *pair_priv = pair->private;
+     struct asrc_config *config = pair_priv->config;
+     int rate[2], select_clk[2]; /* Array size 2 means IN and OUT */
+     int clk_rate, clk_index;
+     int i = 0, j = 0;
+     bool clk_sel[2];
+
+     rate[0] = in_rate;
+     rate[1] = out_rate;
+
+     /* Select proper clock source for internal ratio mode */
+     for (j = 0; j < 2; j++) {
+             for (i = 0; i < ASRC_CLK_MAP_LEN; i++) {
+                     clk_index = asrc_priv->clk_map[j][i];
+                     clk_rate = clk_get_rate(asrc_priv->asrck_clk[clk_index]);

+                       /* Only match a perfect clock source with no remainder */

quoted

+                     if (clk_rate != 0 && (clk_rate / rate[j]) <= 1024 &&
+                         (clk_rate % rate[j]) == 0)
+                             break;
+             }
+
+             if (i == ASRC_CLK_MAP_LEN) {
+                     select_clk[j] = OUTCLK_ASRCK1_CLK;
+                     clk_sel[j] = false;
+             } else {
+                     select_clk[j] = i;
+                     clk_sel[j] = true;
+             }
+     }
+
+     /* Switch to ideal ratio mode if there is no proper clock source */
+     if (!clk_sel[IN] || !clk_sel[OUT])
+             select_clk[IN] = INCLK_NONE;

Could get rid of clk_set:

        for (j) {
                for (i) {
                        if (match)
                                break;
                }

                clk[j] = i;
        }

        if (clk[IN] == ASRC_CLK_MAP_LEN || clk[OUT] == ASRC_CLK_MAP_LEN)

And it only overrides clk[IN] setting but leaving clk[OUT] to
to the searching result. This means that clk[OUT] may be using
a clock source other than OUTCLK_ASRCK1_CLK if sel[IN] happens
to be false while sel[OUT] happens to be true. Not sure if it
is intended...but I feel it would probably be safer to use the
previous settings: INCLK_NONE + OUTCLK_ASRCK1_CLK?

ok, will update the patch.

best regards
wang shengjiu

Hi Shengjiu,

On Mon, Jun 29, 2020 at 11:10 AM Shengjiu Wang [off-list ref] wrote:

+/**

"/**" notation may confuse 'make htmldocs". Since this is a single
line comment you could do:

/* Select proper clock source for internal ratio mode */

+ * Select proper clock source for internal ratio mode
+ */
+static int fsl_asrc_select_clk(struct fsl_asrc_priv *asrc_priv,
+                              struct fsl_asrc_pair *pair,
+                              int in_rate,
+                              int out_rate)
+{
+       struct fsl_asrc_pair_priv *pair_priv = pair->private;
+       struct asrc_config *config = pair_priv->config;
+       int rate[2], select_clk[2]; /* Array size 2 means IN and OUT */
+       int clk_rate, clk_index;
+       int i = 0, j = 0;
+       bool clk_sel[2];
+
+       rate[0] = in_rate;
+       rate[1] = out_rate;
+
+       /* Select proper clock source for internal ratio mode */
+       for (j = 0; j < 2; j++) {
+               for (i = 0; i < ASRC_CLK_MAP_LEN; i++) {
+                       clk_index = asrc_priv->clk_map[j][i];
+                       clk_rate = clk_get_rate(asrc_priv->asrck_clk[clk_index]);
+                       if (clk_rate != 0 && (clk_rate / rate[j]) <= 1024 &&
+                           (clk_rate % rate[j]) == 0)
+                               break;
+               }
+
+               if (i == ASRC_CLK_MAP_LEN) {
+                       select_clk[j] = OUTCLK_ASRCK1_CLK;
+                       clk_sel[j] = false;
+               } else {
+                       select_clk[j] = i;
+                       clk_sel[j] = true;
+               }
+       }
+
+       /* Switch to ideal ratio mode if there is no proper clock source */
+       if (!clk_sel[IN] || !clk_sel[OUT])
+               select_clk[IN] = INCLK_NONE;
+
+       config->inclk = select_clk[IN];
+       config->outclk = select_clk[OUT];
+
+       return 0;

This new function always returns 0. Should it be converted to 'void'
type instead?

+       ret = fsl_asrc_select_clk(asrc_priv, pair,
+                                 config.input_sample_rate,
+                                 config.output_sample_rate);
+       if (ret) {
+               dev_err(dai->dev, "fail to select clock\n");

fsl_asrc_select_clk() does not return error, so you could skip the
error checking.

On Tue, Jun 30, 2020 at 8:38 PM Fabio Estevam [off-list ref] wrote:

Hi Shengjiu,

On Mon, Jun 29, 2020 at 11:10 AM Shengjiu Wang [off-list ref] wrote:

quoted

+/**

"/**" notation may confuse 'make htmldocs". Since this is a single
line comment you could do:

/* Select proper clock source for internal ratio mode */

quoted

+ * Select proper clock source for internal ratio mode
+ */
+static int fsl_asrc_select_clk(struct fsl_asrc_priv *asrc_priv,
+                              struct fsl_asrc_pair *pair,
+                              int in_rate,
+                              int out_rate)
+{
+       struct fsl_asrc_pair_priv *pair_priv = pair->private;
+       struct asrc_config *config = pair_priv->config;
+       int rate[2], select_clk[2]; /* Array size 2 means IN and OUT */
+       int clk_rate, clk_index;
+       int i = 0, j = 0;
+       bool clk_sel[2];
+
+       rate[0] = in_rate;
+       rate[1] = out_rate;
+
+       /* Select proper clock source for internal ratio mode */
+       for (j = 0; j < 2; j++) {
+               for (i = 0; i < ASRC_CLK_MAP_LEN; i++) {
+                       clk_index = asrc_priv->clk_map[j][i];
+                       clk_rate = clk_get_rate(asrc_priv->asrck_clk[clk_index]);
+                       if (clk_rate != 0 && (clk_rate / rate[j]) <= 1024 &&
+                           (clk_rate % rate[j]) == 0)
+                               break;
+               }
+
+               if (i == ASRC_CLK_MAP_LEN) {
+                       select_clk[j] = OUTCLK_ASRCK1_CLK;
+                       clk_sel[j] = false;
+               } else {
+                       select_clk[j] = i;
+                       clk_sel[j] = true;
+               }
+       }
+
+       /* Switch to ideal ratio mode if there is no proper clock source */
+       if (!clk_sel[IN] || !clk_sel[OUT])
+               select_clk[IN] = INCLK_NONE;
+
+       config->inclk = select_clk[IN];
+       config->outclk = select_clk[OUT];
+
+       return 0;

This new function always returns 0. Should it be converted to 'void'
type instead?

quoted

+       ret = fsl_asrc_select_clk(asrc_priv, pair,
+                                 config.input_sample_rate,
+                                 config.output_sample_rate);
+       if (ret) {
+               dev_err(dai->dev, "fail to select clock\n");

fsl_asrc_select_clk() does not return error, so you could skip the
error checking.

ok, will update the patch

best regards
wang shengjiu