[PATCH 2/3] ASoC: rt5668: do not block workqueue if card is unbound

[Kai Vehmanen]

The current rt5668_jack_detect_handler() assumes the component
and card will always show up and implements an infinite usleep
loop waiting for them to show up.

This does not hold true if a codec interrupt (or other
event) occurs when the card is unbound. The codec driver's
remove  or shutdown functions cannot cancel the workqueue due
to the wait loop. As a result, code can either end up blocking
the workqueue, or hit a kernel oops when the card is freed.

Fix the issue by rescheduling the jack detect handler in
case the card is not ready. In case card never shows up,
the shutdown/remove/suspend calls can now cancel the detect
task.

Signed-off-by: Kai Vehmanen <kai.vehmanen at linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao at linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan at linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi at linux.intel.com>
Reviewed-by: Shuming Fan <shumingf at realtek.com>
---
 sound/soc/codecs/rt5668.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/sound/soc/codecs/rt5668.c b/sound/soc/codecs/rt5668.c
index fb09715bf932..5b12cbf2ba21 100644
--- a/sound/soc/codecs/rt5668.c
+++ b/sound/soc/codecs/rt5668.c
@@ -1022,11 +1022,13 @@ static void rt5668_jack_detect_handler(struct work_struct *work)
 		container_of(work, struct rt5668_priv, jack_detect_work.work);
 	int val, btn_type;
 
-	while (!rt5668->component)
-		usleep_range(10000, 15000);
-
-	while (!rt5668->component->card->instantiated)
-		usleep_range(10000, 15000);
+	if (!rt5668->component || !rt5668->component->card ||
+	    !rt5668->component->card->instantiated) {
+		/* card not yet ready, try later */
+		mod_delayed_work(system_power_efficient_wq,
+				 &rt5668->jack_detect_work, msecs_to_jiffies(15));
+		return;
+	}
 
 	mutex_lock(&rt5668->calibrate_mutex);
 
-- 
2.35.1