[alsa-devel] ASOC bug? maybe no need to set bias_level to PREPARE.

[Zhang, Ning A]

When I try to fix wm1811 standby issue for our customer, I find a strange behavior in ASOC core.

here is my test code:

snd_soc_dapm_disable_pin(&dapm,"MICBIAS2");
snd_soc_dapm_disable_pin(&dapm,"CLK_SYS");
snd_soc_dapm_sync(&dapm);

and add debug info in dapm_pre_sequence_async() and we will find these debug info printed: 

d->bias_level = 1
d->target_bias_level = 0
in snd_soc_dapm_set_bias_level

from the debug log, when STANDBY -> OFF transition, it set bias_level to PREPARE.

that's wrong logic.

And more there is comment in source code:
	/* Prepare for a STADDBY->ON or ON->STANDBY transition */ 
But, the code isn't the same as the comment.

----
>From 58d8994bdc543909e9904b8df0787afc36684283 Mon Sep 17 00:00:00 2001
From: ning.a.zhang <ning.a.zhang at intel.com>
Date: Fri, 10 May 2013 09:44:06 +0700
Subject: [PATCH] Asoc dapm behavior fix

in soc_dapm.c, there is a illogic behavior, when bias_level from STANDBY -> OFF transition.
source does not follow its comment.

this patch is based on the comment

Signed-off-by: ning.a.zhang <ning.a.zhang at intel.com>
---
 sound/soc/soc-dapm.c |   14 ++++++++++++--
 1 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/sound/soc/soc-dapm.c b/sound/soc/soc-dapm.c index d6d9ba2..834ab4c 100644
--- a/sound/soc/soc-dapm.c
+++ b/sound/soc/soc-dapm.c
@@ -1486,8 +1486,9 @@ static void dapm_pre_sequence_async(void *data, async_cookie_t cookie)
 				"ASoC: Failed to turn on bias: %d\n", ret);
 	}
 
-	/* Prepare for a STADDBY->ON or ON->STANDBY transition */
-	if (d->bias_level != d->target_bias_level) {
+	/* If we're on and we're not supposed to be go into PREPARE */
+	if (d->bias_level == SND_SOC_BIAS_ON &&
+	    d->target_bias_level != SND_SOC_BIAS_ON) {
 		ret = snd_soc_dapm_set_bias_level(d, SND_SOC_BIAS_PREPARE);
 		if (ret != 0)
 			dev_err(d->dev,
@@ -1525,6 +1526,15 @@ static void dapm_post_sequence_async(void *data, async_cookie_t cookie)
 			pm_runtime_put(d->dev);
 	}
 
+	if (d->bias_level == SND_SOC_BIAS_STANDBY &&
+	    (d->target_bias_level == SND_SOC_BIAS_PREPARE ||
+	     d->target_bias_level == SND_SOC_BIAS_ON)) {
+		ret = snd_soc_dapm_set_bias_level(d, SND_SOC_BIAS_PREPARE);
+		if (ret != 0)
+			dev_err(d->dev, "ASoC: Failed to apply prepare bias: %d\n",
+				ret);
+	}
+
 	/* If we just powered up then move to active bias */
 	if (d->bias_level == SND_SOC_BIAS_PREPARE &&
 	    d->target_bias_level == SND_SOC_BIAS_ON) {
--
1.7.1