linux-kernel - [PATCH AUTOSEL 5.15 10/24] ASoC: wm8962: Wait for updated value of WM8962

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Date:   Mon, 28 Nov 2022 12:40:10 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Chancel Liu <chancel.liu@....com>,
        Charles Keepax <ckeepax@...nsource.cirrus.com>,
        Mark Brown <broonie@...nel.org>,
        Sasha Levin <sashal@...nel.org>, lgirdwood@...il.com,
        perex@...ex.cz, tiwai@...e.com, aford173@...il.com,
        chi.minghao@....com.cn, steve@....org,
        patches@...nsource.cirrus.com, alsa-devel@...a-project.org
Subject: [PATCH AUTOSEL 5.15 10/24] ASoC: wm8962: Wait for updated value of WM8962_CLOCKING1 register

From: Chancel Liu <chancel.liu@....com>

[ Upstream commit 3ca507bf99611c82dafced73e921c1b10ee12869 ]

DSPCLK_DIV field in WM8962_CLOCKING1 register is used to generate
correct frequency of LRCLK and BCLK. Sometimes the read-only value
can't be updated timely after enabling SYSCLK. This results in wrong
calculation values. Delay is introduced here to wait for newest value
from register. The time of the delay should be at least 500~1000us
according to test.

Signed-off-by: Chancel Liu <chancel.liu@....com>
Acked-by: Charles Keepax <ckeepax@...nsource.cirrus.com>
Link: https://lore.kernel.org/r/20221109121354.123958-1-chancel.liu@nxp.com
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 sound/soc/codecs/wm8962.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/sound/soc/codecs/wm8962.c b/sound/soc/codecs/wm8962.c
index 09a73b854964..779f7097d336 100644
--- a/sound/soc/codecs/wm8962.c
+++ b/sound/soc/codecs/wm8962.c
@@ -2490,6 +2490,14 @@ static void wm8962_configure_bclk(struct snd_soc_component *component)
 		snd_soc_component_update_bits(component, WM8962_CLOCKING2,
 				WM8962_SYSCLK_ENA_MASK, WM8962_SYSCLK_ENA);
 
+	/* DSPCLK_DIV field in WM8962_CLOCKING1 register is used to generate
+	 * correct frequency of LRCLK and BCLK. Sometimes the read-only value
+	 * can't be updated timely after enabling SYSCLK. This results in wrong
+	 * calculation values. Delay is introduced here to wait for newest
+	 * value from register. The time of the delay should be at least
+	 * 500~1000us according to test.
+	 */
+	usleep_range(500, 1000);
 	dspclk = snd_soc_component_read(component, WM8962_CLOCKING1);
 
 	if (snd_soc_component_get_bias_level(component) != SND_SOC_BIAS_ON)
-- 
2.35.1