[alsa-devel] [PATCH 2/2] ASoC: dapm: Fix SUSPEND -> OFF bias sequence

[Lars-Peter Clausen]

Currently when the DAPM context bias level is SUSPEND and the target bias level
is OFF dapm_pre_sequence_async() will first transition to PREPARE and
dapm_post_sequence_async() will then transition back from PREPARE to STANDBY and
then to OFF.

This patch makes sure that dapm_pre_sequence_async() only transitions to PREPARE
when either going to ON or away from ON. This avoids the extra unnecessary
transitions.

Signed-off-by: Lars-Peter Clausen <lars at metafoo.de>
---
Given that SUSPEND -> OFF transitions are rather rare and the code will still
work correctly (but inefficent) without this patch, the patch probably does not
need to go into stable.
---
 sound/soc/soc-dapm.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/sound/soc/soc-dapm.c b/sound/soc/soc-dapm.c
index 5d54dfc..562cea8 100644
--- a/sound/soc/soc-dapm.c
+++ b/sound/soc/soc-dapm.c
@@ -1549,8 +1549,11 @@ 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) {
+	/* Prepare for a transition to ON or away from ON */
+	if ((d->target_bias_level == SND_SOC_BIAS_ON &&
+		 d->bias_level != SND_SOC_BIAS_ON) ||
+		(d->target_bias_level != SND_SOC_BIAS_ON &&
+		 d->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,
-- 
1.8.0