[3.19.y-ckt stable] Patch "ASoC: ssm4567: Reset device before regcache_sync()" has been added to the 3.19.y-ckt tree

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    ASoC: ssm4567: Reset device before regcache_sync()

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt18.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From 7aa9801ba3f41d4bbe5b336248ee7f97dc4a91d1 Mon Sep 17 00:00:00 2001
From: Lars-Peter Clausen <lars at metafoo.de>
Date: Wed, 27 Jan 2016 14:26:18 +0100
Subject: ASoC: ssm4567: Reset device before regcache_sync()

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 at intel.com>
Tested-by: Fang, Yang A <yang.a.fang at intel.com>
Signed-off-by: Lars-Peter Clausen <lars at metafoo.de>
Signed-off-by: Mark Brown <broonie at kernel.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 sound/soc/codecs/ssm4567.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/sound/soc/codecs/ssm4567.c b/sound/soc/codecs/ssm4567.c
index f7549cc..d1f53ab 100644
--- a/sound/soc/codecs/ssm4567.c
+++ b/sound/soc/codecs/ssm4567.c
@@ -338,6 +338,11 @@ static int ssm4567_set_power(struct ssm4567 *ssm4567, bool enable)
 	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);
--
2.7.4