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regulator: core: introduce function to lock regulators and its supplies
Each regulator_dev is locked with its own mutex. This is fine as long as only one regulator_dev is locked, but makes lockdep unhappy when we have to walk up the supply chain like it can happen in regulator_get_voltage: regulator_get_voltage -> mutex_lock(®ulator->rdev->mutex) -> _regulator_get_voltage(regulator->rdev) -> regulator_get_voltage(rdev->supply) -> mutex_lock(®ulator->rdev->mutex); This causes lockdep to issue a possible deadlock warning. There are at least two ways to work around this: - We can always lock the whole supply chain using the functions introduced with this patch. - We could store the current voltage in struct regulator_rdev so that we do not have to walk up the supply chain for the _regulator_get_voltage case. Anyway, regulator_lock_supply/regulator_unlock_supply will be needed once we allow regulator_set_voltage to optimize the supply voltages. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> Signed-off-by: Mark Brown <broonie@kernel.org>
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@ -131,6 +131,45 @@ static bool have_full_constraints(void)
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return has_full_constraints || of_have_populated_dt();
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}
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/**
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* regulator_lock_supply - lock a regulator and its supplies
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* @rdev: regulator source
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*/
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static void regulator_lock_supply(struct regulator_dev *rdev)
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{
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struct regulator *supply;
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int i = 0;
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while (1) {
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mutex_lock_nested(&rdev->mutex, i++);
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supply = rdev->supply;
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if (!rdev->supply)
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return;
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rdev = supply->rdev;
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}
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}
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/**
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* regulator_unlock_supply - unlock a regulator and its supplies
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* @rdev: regulator source
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*/
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static void regulator_unlock_supply(struct regulator_dev *rdev)
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{
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struct regulator *supply;
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while (1) {
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mutex_unlock(&rdev->mutex);
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supply = rdev->supply;
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if (!rdev->supply)
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return;
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rdev = supply->rdev;
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}
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}
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/**
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* of_get_regulator - get a regulator device node based on supply name
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* @dev: Device pointer for the consumer (of regulator) device
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