linux-kernel - [PATCH 4.5 112/200] ASoC: ssm4567: Reset device before regcache

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Message-Id: <20160503000558.276992775@linuxfoundation.org>
Date:	Mon,  2 May 2016 17:11:51 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Harsha Priya <harshapriya.n@...el.com>,
	"Fang, Yang A" <yang.a.fang@...el.com>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Mark Brown <broonie@...nel.org>
Subject: [PATCH 4.5 112/200] ASoC: ssm4567: Reset device before regcache_sync()

4.5-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Lars-Peter Clausen <lars@...afoo.de>

commit 712a8038cc24dba668afe82f0413714ca87184e0 upstream.

When the ssm4567 is powered up the driver calles regcache_sync() to restore
the register map content. regcache_sync() assumes that the device is in its
power-on reset state. Make sure that this is the case by explicitly
resetting the ssm4567 register map before calling regcache_sync() otherwise
we might end up with a incorrect register map which leads to undefined
behaviour.

One such undefined behaviour was observed when returning from system
suspend while a playback stream is active, in that case the ssm4567 was
kept muted after resume.

Fixes: 1ee44ce03011 ("ASoC: ssm4567: Add driver for Analog Devices SSM4567 amplifier")
Reported-by: Harsha Priya <harshapriya.n@...el.com>
Tested-by: Fang, Yang A <yang.a.fang@...el.com>
Signed-off-by: Lars-Peter Clausen <lars@...afoo.de>
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 sound/soc/codecs/ssm4567.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/sound/soc/codecs/ssm4567.c
+++ b/sound/soc/codecs/ssm4567.c
@@ -352,6 +352,11 @@ static int ssm4567_set_power(struct ssm4
 	regcache_cache_only(ssm4567->regmap, !enable);
 
 	if (enable) {
+		ret = regmap_write(ssm4567->regmap, SSM4567_REG_SOFT_RESET,
+			0x00);
+		if (ret)
+			return ret;
+
 		ret = regmap_update_bits(ssm4567->regmap,
 			SSM4567_REG_POWER_CTRL,
 			SSM4567_POWER_SPWDN, 0x00);