[PATCH 4.4 089/163] ASoC: ssm4567: Reset device before regcache_sync()

Greg Kroah-Hartman
2016-05-03T00:25:07Z

From: Lars-Peter Clausen <lars@metafoo.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@intel.com>
Tested-by: Fang, Yang A <yang.a.fang@intel.com>
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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);