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3cfe7a74d4
Lockdep validator complains about recursive locking and deadlock when two different regmap instances are called in a nested order. That happens anytime a regmap read/write call needs to access another regmap. This is because, for performance reason, lockdep groups all locks initialized by the same mutex_init() in the same lock class. Therefore all regmap mutexes are in the same lock class, leading to lockdep "nested locking" warnings if a regmap accesses another regmap. In general, it is impossible to establish in advance the hierarchy of regmaps, so we make sure that each regmap init call initializes its own static lock_class_key. This is done by wrapping all regmap_init calls into macros. This also allows us to give meaningful names to the lock_class_key. For example, in rt5677 case, we have in /proc/lockdep_chains: irq_context: 0 [ffffffc0018d2198] &dev->mutex [ffffffc0018d2198] &dev->mutex [ffffffc001bd7f60] rt5677:5104:(&rt5677_regmap)->_lock [ffffffc001bd7f58] rt5677:5096:(&rt5677_regmap_physical)->_lock [ffffffc001b95448] &(&base->lock)->rlock The above would have resulted in a lockdep recursive warning previously. This is not the case anymore as the lockdep validator now clearly identifies the 2 regmaps as separate. Signed-off-by: Nicolas Boichat <drinkcat@chromium.org> Signed-off-by: Mark Brown <broonie@kernel.org> |
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