linux-kernel - [PATCH 1/3] ASoC:codec:max98373: Changed amp shutdown register as volatile

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Date:   Wed, 24 Mar 2021 20:35:53 -0700
From:   Ryan Lee <ryans.lee@...imintegrated.com>
To:     lgirdwood@...il.com, broonie@...nel.org, perex@...ex.cz,
        tiwai@...e.com, pierre-louis.bossart@...ux.intel.com,
        kai.vehmanen@...ux.intel.com, yung-chuan.liao@...ux.intel.com,
        rander.wang@...ux.intel.com, ryans.lee@...imintegrated.com,
        guennadi.liakhovetski@...ux.intel.com, vkoul@...nel.org,
        yong.zhi@...el.com, judyhsiao@...gle.com,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org
Cc:     ryan.lee.maxim@...il.com
Subject: [PATCH 1/3] ASoC:codec:max98373: Changed amp shutdown register as volatile

0x20FF(amp global enable) register was defined as non-volatile,
but it is not. Overheating, overcurrent can cause amp shutdown
in hardware.
'regmap_write' compare register readback value before writing
to avoid same value writing. 'regmap_read' just read cache
not actual hardware value for the non-volatile register.
When amp is internally shutdown by some reason, next 'AMP ON'
command can be ignored because regmap think amp is already ON.

Signed-off-by: Ryan Lee <ryans.lee@...imintegrated.com>
---
 sound/soc/codecs/max98373-i2c.c | 1 +
 sound/soc/codecs/max98373-sdw.c | 1 +
 2 files changed, 2 insertions(+)

diff --git a/sound/soc/codecs/max98373-i2c.c b/sound/soc/codecs/max98373-i2c.c
index 85f6865019d4..ddb6436835d7 100644
--- a/sound/soc/codecs/max98373-i2c.c
+++ b/sound/soc/codecs/max98373-i2c.c
@@ -446,6 +446,7 @@ static bool max98373_volatile_reg(struct device *dev, unsigned int reg)
 	case MAX98373_R2054_MEAS_ADC_PVDD_CH_READBACK:
 	case MAX98373_R2055_MEAS_ADC_THERM_CH_READBACK:
 	case MAX98373_R20B6_BDE_CUR_STATE_READBACK:
+	case MAX98373_R20FF_GLOBAL_SHDN:
 	case MAX98373_R21FF_REV_ID:
 		return true;
 	default:
diff --git a/sound/soc/codecs/max98373-sdw.c b/sound/soc/codecs/max98373-sdw.c
index d8c47667a9ea..f3a12205cd48 100644
--- a/sound/soc/codecs/max98373-sdw.c
+++ b/sound/soc/codecs/max98373-sdw.c
@@ -220,6 +220,7 @@ static bool max98373_volatile_reg(struct device *dev, unsigned int reg)
 	case MAX98373_R2054_MEAS_ADC_PVDD_CH_READBACK:
 	case MAX98373_R2055_MEAS_ADC_THERM_CH_READBACK:
 	case MAX98373_R20B6_BDE_CUR_STATE_READBACK:
+	case MAX98373_R20FF_GLOBAL_SHDN:
 	case MAX98373_R21FF_REV_ID:
 	/* SoundWire Control Port Registers */
 	case MAX98373_R0040_SCP_INIT_STAT_1 ... MAX98373_R0070_SCP_FRAME_CTLR:
-- 
2.17.1