[PATCH 15/16] ASoC: max98363: enable pm_runtime in probe, keep status as 'suspended'

[Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>]

This patch suggests enabling pm_runtime during the probe, but marking the
device as 'active' only after it is enumerated. That will force a
dependency between the card and the codec, pm_runtime_get_sync() will
have to wait for the codec device to resume and hence implicitly wait
for the enumeration/initialization to be completed. In the nominal
case where the codec device is already active the get_sync() would
only perform a ref-count increase.

The changes are directly inspired by RT711 and RT711-sdca changes.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@xxxxxxxxxxxxxxx>
Reviewed-by: Rander Wang <rander.wang@xxxxxxxxx>
Reviewed-by: Bard Liao <yung-chuan.liao@xxxxxxxxxxxxxxx>
---
 sound/soc/codecs/max98363.c | 34 ++++++++++++++++++++--------------
 1 file changed, 20 insertions(+), 14 deletions(-)

diff --git a/sound/soc/codecs/max98363.c b/sound/soc/codecs/max98363.c
index 80a1cb482183..9e3873e56e6d 100644
--- a/sound/soc/codecs/max98363.c
+++ b/sound/soc/codecs/max98363.c
@@ -165,22 +165,12 @@ static int max98363_io_init(struct sdw_slave *slave)
 		regcache_cache_bypass(max98363->regmap, true);
 
 	/*
-	 * PM runtime is only enabled when a Slave reports as Attached
+	 * PM runtime status is marked as 'active' only when a Slave reports as Attached
 	 */
-	if (!max98363->first_hw_init) {
-		/* set autosuspend parameters */
-		pm_runtime_set_autosuspend_delay(dev, 3000);
-		pm_runtime_use_autosuspend(dev);
-
+	if (!max98363->first_hw_init)
 		/* update count of parent 'active' children */
 		pm_runtime_set_active(dev);
 
-		/* make sure the device does not suspend immediately */
-		pm_runtime_mark_last_busy(dev);
-
-		pm_runtime_enable(dev);
-	}
-
 	pm_runtime_get_noresume(dev);
 
 	ret = regmap_read(max98363->regmap, MAX98363_R21FF_REV_ID, &reg);
@@ -417,10 +407,26 @@ static int max98363_init(struct sdw_slave *slave, struct regmap *regmap)
 	ret = devm_snd_soc_register_component(dev, &soc_codec_dev_max98363,
 					      max98363_dai,
 					      ARRAY_SIZE(max98363_dai));
-	if (ret < 0)
+	if (ret < 0) {
 		dev_err(dev, "Failed to register codec: %d\n", ret);
+		return ret;
+	}
 
-	return ret;
+	/* set autosuspend parameters */
+	pm_runtime_set_autosuspend_delay(dev, 3000);
+	pm_runtime_use_autosuspend(dev);
+
+	/* make sure the device does not suspend immediately */
+	pm_runtime_mark_last_busy(dev);
+
+	pm_runtime_enable(dev);
+
+	/* important note: the device is NOT tagged as 'active' and will remain
+	 * 'suspended' until the hardware is enumerated/initialized. This is required
+	 * to make sure the ASoC framework use of pm_runtime_get_sync() does not silently
+	 * fail with -EACCESS because of race conditions between card creation and enumeration
+	 */
+	return 0;
 }
 
 static int max98363_sdw_probe(struct sdw_slave *slave,
-- 
2.39.2