[PATCH v2 0/2] ASoC: codec: wm8960: Relax bit clock computation when using PLL

[PATCH v2 0/2] ASoC: codec: wm8960: Relax bit clock computation when using PLL

[Daniel Baluta]

This is a follow up of commit 3c01b9ee2ab ("ASoC: codec: wm8960: Relax bit clock computation")
where we relaxed bitclk when sysclk was derived from MCLK.

Now, we do the same thing for sysclk derived using PLL.

Changes since v1:
	* fixed "may be used uninitialized" warnings [i strongly believe
	they were compiler false positive - see full warning log here (1)]
	* fixed break for inner loop

[1] http://mailman.alsa-project.org/pipermail/alsa-devel/2017-April/119513.html

Daniel Baluta (2):
  ASoC: codec: wm9860: Refactor PLL out freq search
  ASoC: codec: wm8960: Relax bit clock computation when using PLL

 sound/soc/codecs/wm8960.c | 109 ++++++++++++++++++++++++++++++++++------------
 1 file changed, 80 insertions(+), 29 deletions(-)

-- 
2.7.4

[PATCH v2 1/2] ASoC: codec: wm9860: Refactor PLL out freq search

[Daniel Baluta]

Add a separate function for deriving (sysclk, lrclk, bclk)
when the clock is auto or pll.

Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
---
 sound/soc/codecs/wm8960.c | 97 +++++++++++++++++++++++++++++++++--------------
 1 file changed, 68 insertions(+), 29 deletions(-)

diff --git a/sound/soc/codecs/wm8960.c b/sound/soc/codecs/wm8960.c
index ce159f1..1c973f0 100644
--- a/sound/soc/codecs/wm8960.c
+++ b/sound/soc/codecs/wm8960.c
@@ -672,10 +672,74 @@ int wm8960_configure_sysclk(struct wm8960_priv *wm8960, int mclk,
 	return *bclk_idx;
 }
 
+/**
+ * wm8960_configure_pll - checks if there is a PLL out frequency available
+ *	The PLL out frequency must be chosen such that:
+ *		- sysclk      = lrclk * dac_divs
+ *		- freq_out    = sysclk * sysclk_divs
+ *		- 10 * sysclk = bclk * bclk_divs
+ *
+ * @codec: codec structure
+ * @freq_in: input frequency used to derive freq out via PLL
+ * @sysclk_idx: sysclk_divs index for found sysclk
+ * @dac_idx: dac_divs index for found lrclk
+ * @bclk_idx: bclk_divs index for found bclk
+ *
+ * Returns:
+ *  -1, in case no PLL frequency out available was found
+ * >=0, in case we could derive bclk, lrclk, sysclk from PLL out using
+ *      (@sysclk_idx, @dac_idx, @bclk_idx) dividers
+ */
+static
+int wm8960_configure_pll(struct snd_soc_codec *codec, int freq_in,
+			 int *sysclk_idx, int *dac_idx, int *bclk_idx)
+{
+	struct wm8960_priv *wm8960 = snd_soc_codec_get_drvdata(codec);
+	int sysclk, bclk, lrclk, freq_out;
+	int diff, best_freq_out = 0;
+	int i, j, k;
+
+	bclk = wm8960->bclk;
+	lrclk = wm8960->lrclk;
+
+	*bclk_idx = *dac_idx = *sysclk_idx = -1;
+
+	for (i = 0; i < ARRAY_SIZE(sysclk_divs); ++i) {
+		if (sysclk_divs[i] == -1)
+			continue;
+		for (j = 0; j < ARRAY_SIZE(dac_divs); ++j) {
+			sysclk = lrclk * dac_divs[j];
+			freq_out = sysclk * sysclk_divs[i];
+
+			for (k = 0; k < ARRAY_SIZE(bclk_divs); ++k) {
+				if (!is_pll_freq_available(freq_in, freq_out))
+					continue;
+
+				diff = sysclk - bclk * bclk_divs[k] / 10;
+				if (diff == 0) {
+					*sysclk_idx = i;
+					*dac_idx = j;
+					*bclk_idx = k;
+					best_freq_out = freq_out;
+					break;
+				}
+			}
+			if (k != ARRAY_SIZE(bclk_divs))
+				break;
+		}
+		if (j != ARRAY_SIZE(dac_divs))
+			break;
+	}
+
+	if (*bclk_idx != -1)
+		wm8960_set_pll(codec, freq_in, best_freq_out);
+
+	return *bclk_idx;
+}
 static int wm8960_configure_clocking(struct snd_soc_codec *codec)
 {
 	struct wm8960_priv *wm8960 = snd_soc_codec_get_drvdata(codec);
-	int sysclk, bclk, lrclk, freq_out, freq_in;
+	int freq_out, freq_in;
 	u16 iface1 = snd_soc_read(codec, WM8960_IFACE1);
 	int i, j, k;
 	int ret;
@@ -692,8 +756,6 @@ static int wm8960_configure_clocking(struct snd_soc_codec *codec)
 	}
 
 	freq_in = wm8960->freq_in;
-	bclk = wm8960->bclk;
-	lrclk = wm8960->lrclk;
 	/*
 	 * If it's sysclk auto mode, check if the MCLK can provide sysclk or
 	 * not. If MCLK can provide sysclk, using MCLK to provide sysclk
@@ -720,33 +782,10 @@ static int wm8960_configure_clocking(struct snd_soc_codec *codec)
 			return -EINVAL;
 		}
 	}
-	/* get a available pll out frequency and set pll */
-	for (i = 0; i < ARRAY_SIZE(sysclk_divs); ++i) {
-		if (sysclk_divs[i] == -1)
-			continue;
-		for (j = 0; j < ARRAY_SIZE(dac_divs); ++j) {
-			sysclk = lrclk * dac_divs[j];
-			freq_out = sysclk * sysclk_divs[i];
-
-			for (k = 0; k < ARRAY_SIZE(bclk_divs); ++k) {
-				if (sysclk == bclk * bclk_divs[k] / 10 &&
-				    is_pll_freq_available(freq_in, freq_out)) {
-					wm8960_set_pll(codec,
-						       freq_in, freq_out);
-					break;
-				} else {
-					continue;
-				}
-			}
-			if (k != ARRAY_SIZE(bclk_divs))
-				break;
-		}
-		if (j != ARRAY_SIZE(dac_divs))
-			break;
-	}
 
-	if (i == ARRAY_SIZE(sysclk_divs)) {
-		dev_err(codec->dev, "failed to configure clock\n");
+	ret = wm8960_configure_pll(codec, freq_in, &i, &j, &k);
+	if (ret < 0) {
+		dev_err(codec->dev, "failed to configure clock via PLL\n");
 		return -EINVAL;
 	}
 
-- 
2.7.4

[PATCH v2 2/2] ASoC: codec: wm8960: Relax bit clock computation when using PLL

[Daniel Baluta]

Bitclk is derived from sysclk using bclk_divs.
Sysclk can be derived in two ways:
	(1) directly from MLCK
	(2) MCLK via PLL

Commit 3c01b9ee2ab9d0d ("ASoC: codec: wm8960: Relax bit clock
computation")
relaxed bitclk computation when sysclk is directly derived from MCLK.

Lets do the same thing when sysclk is derived via PLL.

Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
---
 sound/soc/codecs/wm8960.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/sound/soc/codecs/wm8960.c b/sound/soc/codecs/wm8960.c
index 1c973f0..8ab9fa2 100644
--- a/sound/soc/codecs/wm8960.c
+++ b/sound/soc/codecs/wm8960.c
@@ -679,6 +679,10 @@ int wm8960_configure_sysclk(struct wm8960_priv *wm8960, int mclk,
  *		- freq_out    = sysclk * sysclk_divs
  *		- 10 * sysclk = bclk * bclk_divs
  *
+ *	If we cannot find an exact match for (sysclk, lrclk, bclk)
+ *	triplet, we relax the bclk such that bclk is chosen as the
+ *	closest available frequency greater than expected bclk.
+ *
  * @codec: codec structure
  * @freq_in: input frequency used to derive freq out via PLL
  * @sysclk_idx: sysclk_divs index for found sysclk
@@ -696,11 +700,12 @@ int wm8960_configure_pll(struct snd_soc_codec *codec, int freq_in,
 {
 	struct wm8960_priv *wm8960 = snd_soc_codec_get_drvdata(codec);
 	int sysclk, bclk, lrclk, freq_out;
-	int diff, best_freq_out = 0;
+	int diff, closest, best_freq_out = 0;
 	int i, j, k;
 
 	bclk = wm8960->bclk;
 	lrclk = wm8960->lrclk;
+	closest = freq_in;
 
 	*bclk_idx = *dac_idx = *sysclk_idx = -1;
 
@@ -723,6 +728,13 @@ int wm8960_configure_pll(struct snd_soc_codec *codec, int freq_in,
 					best_freq_out = freq_out;
 					break;
 				}
+				if (diff > 0 && closest > diff) {
+					*sysclk_idx = i;
+					*dac_idx = j;
+					*bclk_idx = k;
+					closest = diff;
+					best_freq_out = freq_out;
+				}
 			}
 			if (k != ARRAY_SIZE(bclk_divs))
 				break;
-- 
2.7.4