lockdep complains recursive locking and deadlock when two different
regmap instances are called in a nested order. That happen easily
for example when both I2C client and muxed/repeater I2C adapter are
using regmap. As a solution, pass regmap name for lockdep in order
to force lockdep validate regmap mutex per driver - not as all regmap
instances grouped together.
Here is example connection, where nested regmap is used to control
I2C mux.
__________ ___________ ___________
| USB IF | | demod | | tuner |
|----------| |-----------| |-----------|
| |--I2C--|-----/ ----|--I2C--| |
|I2C master| | I2C mux | | I2C slave |
|__________| |___________| |___________|
Cc: Mark Brown <broo...@kernel.org>
Signed-off-by: Antti Palosaari <cr...@iki.fi>
---
drivers/base/regmap/regmap.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index d2f8a81..8d8ad37 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -559,6 +559,12 @@ struct regmap *regmap_init(struct device *dev,
mutex_init(&map->mutex);
map->lock = regmap_lock_mutex;
map->unlock = regmap_unlock_mutex;
+ if (config->name) {
+ static struct lock_class_key key;
+
+ lockdep_set_class_and_name(&map->mutex, &key,
+ config->name);
+ }
}
map->lock_arg = map;
}
--
http://palosaari.fi/
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