linux-kernel - [PATCH 2/4] ASoC: tas2764: Wait for ramp-down after shutdown

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Message-Id: <20250208-asoc-tas2764-v1-2-dbab892a69b5@kernel.org>
Date: Sat, 08 Feb 2025 01:03:25 +0000
From: broonie@...nel.org
To: Shenghao Ding <shenghao-ding@...com>, Kevin Lu <kevin-lu@...com>, 
 Baojun Xu <baojun.xu@...com>, Liam Girdwood <lgirdwood@...il.com>, 
 Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>, 
 Dan Murphy <dmurphy@...com>, Hector Martin <marcan@...can.st>, 
 Martin Povišer <povik+lin@...ebit.org>
Cc: linux-sound@...r.kernel.org, linux-kernel@...r.kernel.org, 
 devicetree@...r.kernel.org, Mark Brown <broonie@...nel.org>
Subject: [PATCH 2/4] ASoC: tas2764: Wait for ramp-down after shutdown

From: Hector Martin <marcan@...can.st>

When we shut down the amp, we need to wait for the built-in ramp-down
before we can remove the TDM clocks. There is no documented status
regiter to poll, so the best we can do is a delay. Datasheet says 5.9ms
for ramp-down and 1.5ms between shutdown and next startup, so let's do
6ms after mute and 2ms after shutdown. That gives us a cumulative 8ms
for ramp-down and guaratees the required minimum shutdown time.

Signed-off-by: Hector Martin <marcan@...can.st>
Signed-off-by: Mark Brown <broonie@...nel.org>
---
 sound/soc/codecs/tas2764.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/sound/soc/codecs/tas2764.c b/sound/soc/codecs/tas2764.c
index 60d660a88fab..0b033ab51f7f 100644
--- a/sound/soc/codecs/tas2764.c
+++ b/sound/soc/codecs/tas2764.c
@@ -142,6 +142,8 @@ static int tas2764_codec_suspend(struct snd_soc_component *component)
 	regcache_cache_only(tas2764->regmap, true);
 	regcache_mark_dirty(tas2764->regmap);
 
+	usleep_range(6000, 7000);
+
 	return 0;
 }
 
@@ -228,10 +230,16 @@ static int tas2764_mute(struct snd_soc_dai *dai, int mute, int direction)
 		return ret;
 
 	if (mute) {
+		/* Wait for ramp-down */
+		usleep_range(6000, 7000);
+
 		tas2764->dac_powered = false;
 		ret = tas2764_update_pwr_ctrl(tas2764);
 		if (ret)
 			return ret;
+
+		/* Wait a bit after shutdown */
+		usleep_range(2000, 3000);
 	}
 
 	return 0;

-- 
2.39.5