linux-kernel - [PATCH 12/15] ASoC: cs42l42: Wait at least 150us after writing SCLK

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Date:   Tue, 2 Mar 2021 17:04:51 +0000
From:   Lucas Tanure <tanureal@...nsource.cirrus.com>
To:     James Schulman <james.schulman@...rus.com>,
        David Rhodes <david.rhodes@...rus.com>,
        Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>
CC:     Richard Fitzgerald <rf@...nsource.cirrus.com>,
        <alsa-devel@...a-project.org>, <patches@...nsource.cirrus.com>,
        Lucas Tanure <tanureal@...nsource.cirrus.com>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH 12/15] ASoC: cs42l42: Wait at least 150us after writing SCLK_PRESENT

From: Richard Fitzgerald <rf@...nsource.cirrus.com>

There must be a delay of at least 150us after writing SCLK_PRESENT
before issuing another I2C write.

This is done using struct reg_sequence because it can specify a delay
after the write and the whole sequence is written atomically.

Signed-off-by: Richard Fitzgerald <rf@...nsource.cirrus.com>
---
 sound/soc/codecs/cs42l42.c | 28 +++++++++++++++++++++++-----
 sound/soc/codecs/cs42l42.h |  1 +
 2 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/sound/soc/codecs/cs42l42.c b/sound/soc/codecs/cs42l42.c
index 7898a2d52a3b7..5755f8baddbcf 100644
--- a/sound/soc/codecs/cs42l42.c
+++ b/sound/soc/codecs/cs42l42.c
@@ -517,6 +517,24 @@ static const struct snd_soc_dapm_route cs42l42_audio_map[] = {
 	{ "SDOUT2", NULL, "ASP TX EN" },
 };
 
+/* Switch to SCLK. Atomic delay after the write to allow the switch to complete. */
+static const struct reg_sequence cs42l42_to_sclk_seq[] = {
+	{
+		.reg = CS42L42_OSC_SWITCH,
+		.def = CS42L42_SCLK_PRESENT_MASK,
+		.delay_us = CS42L42_CLOCK_SWITCH_DELAY_US,
+	},
+};
+
+/* Switch to OSC. Atomic delay after the write to allow the switch to complete. */
+static const struct reg_sequence cs42l42_to_osc_seq[] = {
+	{
+		.reg = CS42L42_OSC_SWITCH,
+		.def = 0,
+		.delay_us = CS42L42_CLOCK_SWITCH_DELAY_US,
+	},
+};
+
 struct cs42l42_pll_params {
 	u32 sclk;
 	u8 mclk_div;
@@ -809,6 +827,7 @@ static int cs42l42_set_sysclk(struct snd_soc_dai *dai,
 static int cs42l42_mute_stream(struct snd_soc_dai *dai, int mute, int stream)
 {
 	struct snd_soc_component *component = dai->component;
+	struct cs42l42_private *cs42l42 = snd_soc_component_get_drvdata(component);
 	unsigned int regval;
 	u8 fullScaleVol;
 
@@ -828,8 +847,8 @@ static int cs42l42_mute_stream(struct snd_soc_dai *dai, int mute, int stream)
 			 * SCLK must remain running until after this clock switch.
 			 * Without a source of clock the I2C bus doesn't work.
 			 */
-			snd_soc_component_update_bits(component, CS42L42_OSC_SWITCH,
-						      CS42L42_SCLK_PRESENT_MASK, 0);
+			regmap_multi_reg_write(cs42l42->regmap, cs42l42_to_osc_seq,
+					       ARRAY_SIZE(cs42l42_to_osc_seq));
 			snd_soc_component_update_bits(component, CS42L42_PLL_CTL1,
 						      CS42L42_PLL_START_MASK, 0);
 		}
@@ -840,9 +859,8 @@ static int cs42l42_mute_stream(struct snd_soc_dai *dai, int mute, int stream)
 						      CS42L42_PLL_START_MASK, 1);
 
 			/* Mark SCLK as present, turn off internal oscillator */
-			snd_soc_component_update_bits(component, CS42L42_OSC_SWITCH,
-						      CS42L42_SCLK_PRESENT_MASK,
-						      CS42L42_SCLK_PRESENT_MASK);
+			regmap_multi_reg_write(cs42l42->regmap, cs42l42_to_sclk_seq,
+					       ARRAY_SIZE(cs42l42_to_sclk_seq));
 		}
 		cs42l42->stream_use |= 1 << stream;
 
diff --git a/sound/soc/codecs/cs42l42.h b/sound/soc/codecs/cs42l42.h
index 1df9577e367c1..a0c87f2326e69 100644
--- a/sound/soc/codecs/cs42l42.h
+++ b/sound/soc/codecs/cs42l42.h
@@ -755,6 +755,7 @@
 
 #define CS42L42_NUM_SUPPLIES	5
 #define CS42L42_BOOT_TIME_US	3000
+#define CS42L42_CLOCK_SWITCH_DELAY_US 150
 
 static const char *const cs42l42_supply_names[CS42L42_NUM_SUPPLIES] = {
 	"VA",
-- 
2.30.1