ASoC: rt5682-sdw: fix race condition on system suspend

In the initial driver we cancelled deferred work, but there is still a
window of time where a new interrupt could result in new deferred work
executed after the link is disabled, leading to an IO error. While we
did not see this IO error on RT5682-based platforms, the code pattern
is similar to the RT700 case where the IO error was noted, so the fix
is added for consistency.

This patch uses an 'disable_irq_lock' mutex to prevent new interrupts
from happening after the start of the system suspend. The choice of a
mutex v. a spinlock is mainly due to the time required to clear
interrupts, which requires a command to be transmitted by the
SoundWire host IP and acknowledged with an interrupt. The
'interrupt_callback' routine is also not meant to be called from an
interrupt context.

An additional 'disable_irq' flag prevents race conditions where the
status changes before the interrupts are disabled, but the workqueue
handling status changes is scheduled after the completion of the
system suspend. On resume the interrupts are re-enabled already by the
io_init routine so we only clear the flag.

The Fixes tag points to a 5.10 commit, there's no need to propagate
this change to earlier upstream versions.

BugLink: https://github.com/thesofproject/linux/issues/2943
Fixes: 4a55000722d7 ('ASoC: codecs: rt*.c: remove useless pointer cast')
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Bard Liao <bard.liao@intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Link: https://lore.kernel.org/r/20210614180815.153711-5-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/sound/soc/codecs/rt5682.h b/sound/soc/codecs/rt5682.h
index 74ff66767016..b59221048ebf 100644
--- a/sound/soc/codecs/rt5682.h
+++ b/sound/soc/codecs/rt5682.h
@@ -1415,6 +1415,8 @@ struct rt5682_priv {
 	struct regulator_bulk_data supplies[RT5682_NUM_SUPPLIES];
 	struct delayed_work jack_detect_work;
 	struct delayed_work jd_check_work;
+	struct mutex disable_irq_lock; /* imp-def irq lock protection */
+	bool disable_irq;
 	struct mutex calibrate_mutex;
 	struct sdw_slave *slave;
 	enum sdw_slave_status status;