[PATCH] ASoC: da7219: Make more efficient use of MCLK within driver

[Adam Thomson <Adam.Thomson.Opensource@diasemi.com>]

Currently, if the driver has control of MCLK then it remains
enabled as long as the codec is in STANDBY or above. The MCLK is
only really required in STANDBY when a 3-pole jack is inserted
and the HP detect procedure is required to run.

This patch updates the code to enable/disable the MCLK when moving
between the STANDBY and PREPARE bias level, and when a 3-pole jack
is inserted and HP detection is required, thus saving power at all
other times.

Signed-off-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
---
 sound/soc/codecs/da7219-aad.c | 18 +++++++++++++++++-
 sound/soc/codecs/da7219.c     | 18 +++++++++++-------
 2 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/sound/soc/codecs/da7219-aad.c b/sound/soc/codecs/da7219-aad.c
index f0057cd..4e369a1 100644
--- a/sound/soc/codecs/da7219-aad.c
+++ b/sound/soc/codecs/da7219-aad.c
@@ -13,6 +13,7 @@
 
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <linux/clk.h>
 #include <linux/i2c.h>
 #include <linux/property.h>
 #include <linux/pm_wakeirq.h>
@@ -115,12 +116,23 @@ static void da7219_aad_hptest_work(struct work_struct *work)
 
 	u16 tonegen_freq_hptest;
 	u8 accdet_cfg8;
-	int report = 0;
+	int report = 0, ret = 0;
 
 	/* Lock DAPM and any Kcontrols that are affected by this test */
 	snd_soc_dapm_mutex_lock(dapm);
 	mutex_lock(&da7219->lock);
 
+	/* Ensure MCLK is available for HP test procedure */
+	if (da7219->mclk) {
+		ret = clk_prepare_enable(da7219->mclk);
+		if (ret) {
+			dev_err(codec->dev, "Failed to enable mclk - %d\n", ret);
+			mutex_unlock(&da7219->lock);
+			snd_soc_dapm_mutex_unlock(dapm);
+			return;
+		}
+	}
+
 	/* Bypass cache so it saves current settings */
 	regcache_cache_bypass(da7219->regmap, true);
 
@@ -250,6 +262,10 @@ static void da7219_aad_hptest_work(struct work_struct *work)
 	snd_soc_update_bits(codec, DA7219_HP_R_CTRL, DA7219_HP_R_AMP_OE_MASK,
 			    DA7219_HP_R_AMP_OE_MASK);
 
+	/* Remove MCLK, if previously enabled */
+	if (da7219->mclk)
+		clk_disable_unprepare(da7219->mclk);
+
 	mutex_unlock(&da7219->lock);
 	snd_soc_dapm_mutex_unlock(dapm);
 
diff --git a/sound/soc/codecs/da7219.c b/sound/soc/codecs/da7219.c
index 50ea943..737e914 100644
--- a/sound/soc/codecs/da7219.c
+++ b/sound/soc/codecs/da7219.c
@@ -1508,11 +1508,10 @@ static int da7219_set_bias_level(struct snd_soc_codec *codec,
 
 	switch (level) {
 	case SND_SOC_BIAS_ON:
-	case SND_SOC_BIAS_PREPARE:
 		break;
-	case SND_SOC_BIAS_STANDBY:
-		if (snd_soc_codec_get_bias_level(codec) == SND_SOC_BIAS_OFF) {
-			/* MCLK */
+	case SND_SOC_BIAS_PREPARE:
+		/* Enable MCLK for transition to ON state */
+		if (snd_soc_codec_get_bias_level(codec) == SND_SOC_BIAS_STANDBY) {
 			if (da7219->mclk) {
 				ret = clk_prepare_enable(da7219->mclk);
 				if (ret) {
@@ -1521,11 +1520,19 @@ static int da7219_set_bias_level(struct snd_soc_codec *codec,
 					return ret;
 				}
 			}
+		}
 
+		break;
+	case SND_SOC_BIAS_STANDBY:
+		if (snd_soc_codec_get_bias_level(codec) == SND_SOC_BIAS_OFF) {
 			/* Master bias */
 			snd_soc_update_bits(codec, DA7219_REFERENCES,
 					    DA7219_BIAS_EN_MASK,
 					    DA7219_BIAS_EN_MASK);
+		} else {
+			/* Remove MCLK */
+			if (da7219->mclk)
+				clk_disable_unprepare(da7219->mclk);
 		}
 		break;
 	case SND_SOC_BIAS_OFF:
@@ -1534,9 +1541,6 @@ static int da7219_set_bias_level(struct snd_soc_codec *codec,
 			snd_soc_update_bits(codec, DA7219_REFERENCES,
 					    DA7219_BIAS_EN_MASK, 0);
 
-		/* MCLK */
-		if (da7219->mclk)
-			clk_disable_unprepare(da7219->mclk);
 		break;
 	}
 
-- 
1.9.3