linux-kernel - [PATCH 3.16 014/202] ASoC: tlv320aic32x4: Kernel OOPS while entering DAPM standby mode

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Message-ID: <lsq.1556377989.116761540@decadent.org.uk>
Date:   Sat, 27 Apr 2019 16:13:09 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Mark Brown" <broonie@...nel.org>, "b-ak" <anur.bhargav@...il.com>
Subject: [PATCH 3.16 014/202] ASoC: tlv320aic32x4: Kernel OOPS while
 entering DAPM standby mode

3.16.66-rc1 review patch.  If anyone has any objections, please let me know.

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

From: b-ak <anur.bhargav@...il.com>

commit 667e9334fa64da2273e36ce131b05ac9e47c5769 upstream.

During the bootup of the kernel, the DAPM bias level is in the OFF
state. As soon as the DAPM framework kicks in it pushes the codec
into STANDBY state.

The probe function doesn't prepare the clock, and STANDBY state
does a clk_disable_unprepare() without checking the previous state.
This leads to an OOPS.

Not transitioning from an OFF state to the STANDBY state fixes the
problem.

Signed-off-by: b-ak <anur.bhargav@...il.com>
Signed-off-by: Mark Brown <broonie@...nel.org>
[bwh: Backported to 3.16:
 - Open-code snd_soc_component_get_bias_level()
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 sound/soc/codecs/tlv320aic32x4.c | 4 ++++
 1 file changed, 4 insertions(+)

--- a/sound/soc/codecs/tlv320aic32x4.c
+++ b/sound/soc/codecs/tlv320aic32x4.c
@@ -534,6 +534,10 @@ static int aic32x4_set_bias_level(struct
 	case SND_SOC_BIAS_PREPARE:
 		break;
 	case SND_SOC_BIAS_STANDBY:
+		/* Initial cold start */
+		if (codec->dapm.bias_level == SND_SOC_BIAS_OFF)
+			break;
+
 		/* Switch off BCLK_N Divider */
 		snd_soc_update_bits(codec, AIC32X4_BCLKN,
 				    AIC32X4_BCLKEN, 0);