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regulator: core: Make locks re-entrant

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Setting voltage, enabling/disabling regulators requires operations on
all regulators related with the regulator being changed. Therefore,
all of them should be locked for the whole operation. With the current
locking implementation, adding additional dependency (regulators
coupling) causes deadlocks in some cases.

Introduce a possibility to attempt to lock a mutex multiple times
by the same task without waiting on a mutex. This should handle all
reasonable coupling-supplying combinations, especially when two coupled
regulators share common supplies. The only situation that should be
forbidden is simultaneous coupling and supplying between a pair of
regulators.

The idea is based on clk core.

Signed-off-by: Maciej Purski <m.purski@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Maciej Purski
2018-04-23 16:33:37 +02:00
committed by Mark Brown
parent 0369e02b75
commit 66cf9a7e01
2 changed files with 93 additions and 41 deletions
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2
include/linux/regulator/driver.h
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@@ -434,6 +434,8 @@ struct regulator_dev {
struct blocking_notifier_head notifier;
struct mutex mutex; /* consumer lock */
struct task_struct *mutex_owner;
int ref_cnt;
struct module *owner;
struct device dev;
struct regulation_constraints *constraints;