linux-kernel - [PATCH 1/2] ASoc: fsl_micfil: explicitly clear software reset bit

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Date:   Sat,  7 May 2022 20:14:13 +0800
From:   Shengjiu Wang <shengjiu.wang@....com>
To:     nicoleotsuka@...il.com, Xiubo.Lee@...il.com, festevam@...il.com,
        shengjiu.wang@...il.com, lgirdwood@...il.com, broonie@...nel.org,
        perex@...ex.cz, tiwai@...e.com, alsa-devel@...a-project.org
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] ASoc: fsl_micfil: explicitly clear software reset bit

SRES is self-cleared bit, but REG_MICFIL_CTRL1 is defined as
non volatile register, it still remain in regmap cache after set,
then every update of REG_MICFIL_CTRL1, software reset happens.
to avoid this, clear it explicitly.

Signed-off-by: Shengjiu Wang <shengjiu.wang@....com>
---
 sound/soc/fsl/fsl_micfil.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/sound/soc/fsl/fsl_micfil.c b/sound/soc/fsl/fsl_micfil.c
index cd85c8714f97..2149fac0dcc6 100644
--- a/sound/soc/fsl/fsl_micfil.c
+++ b/sound/soc/fsl/fsl_micfil.c
@@ -179,6 +179,17 @@ static int fsl_micfil_reset(struct device *dev)
 	if (ret)
 		return ret;
 
+	/*
+	 * SRES is self-cleared bit, but REG_MICFIL_CTRL1 is defined
+	 * as non-volatile register, so SRES still remain in regmap
+	 * cache after set, that every update of REG_MICFIL_CTRL1,
+	 * software reset happens. so clear it explicitly.
+	 */
+	ret = regmap_clear_bits(micfil->regmap, REG_MICFIL_CTRL1,
+				MICFIL_CTRL1_SRES);
+	if (ret)
+		return ret;
+
 	return 0;
 }
 
-- 
2.17.1