linux-kernel - [PATCH v3 13/15] ASoC: cs42l42: Wait at least 150us after writing SCLK

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Date:   Sat, 6 Mar 2021 18:55:51 +0000
From:   Lucas Tanure <tanureal@...nsource.cirrus.com>
To:     James Schulman <james.schulman@...rus.com>,
        David Rhodes <david.rhodes@...rus.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>
CC:     <alsa-devel@...a-project.org>, <linux-kernel@...r.kernel.org>,
        <patches@...nsource.cirrus.com>,
        Richard Fitzgerald <rf@...nsource.cirrus.com>,
        Lucas Tanure <tanureal@...nsource.cirrus.com>
Subject: [PATCH v3 13/15] 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>
Signed-off-by: Lucas Tanure <tanureal@...nsource.cirrus.com>
---
Changes in v3:
- No changes

Changes in v2:
- struct cs42l42_private add by this patch was wrong and moved to the
correct patch
- Lucas signed-off added

 sound/soc/codecs/cs42l42.c | 27 ++++++++++++++++++++++-----
 sound/soc/codecs/cs42l42.h |  1 +
 2 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/sound/soc/codecs/cs42l42.c b/sound/soc/codecs/cs42l42.c
index 68b7ed71ad542..08718fd10fb9b 100644
--- a/sound/soc/codecs/cs42l42.c
+++ b/sound/soc/codecs/cs42l42.c
@@ -549,6 +549,24 @@ static const struct snd_soc_component_driver soc_component_dev_cs42l42 = {
 	.non_legacy_dai_naming	= 1,
 };
 
+/* 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;
@@ -861,8 +879,8 @@ 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);
 		}
@@ -873,9 +891,8 @@ 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 429c6833fc811..214cee762709d 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