Messages in this thread Patch in this message | | | From | Alexandru Ardelean <> | Subject | [RFC PATCH] regulator: devres: disable regulator on release if refcount is 1 | Date | Fri, 25 Jun 2021 15:53:07 +0300 |
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Evidently, this came about after doing a few of these types of constructs:
static void reg_disable(void *reg) { regulator_disable(reg) }
...
ret = regulator_enable(reg); if (ret) return ret;
ret = devm_add_action_or_reset(dev, reg_disable, reg);
...
Naturally, the first thought was to try to move this construct into regulator core, but I remembered that a devm_regulator_enable() function isn't all that loved. The construct above looks like it could become a short-hand (in the form of devm_regulator_enable()), somewhere in the regulator framework.
After going back through the previous discussions [referenced below, sorry if I missed any], it looks like maybe an idea would be to call regulator_disable() right before regulator_put() inside devm_regulator_release(). But we need to call it only if the 'enable_count' is 1.
This means that the last 'regulator_disable()' (on driver remove) becomes optional. If there are any unbalanced regulator_enable()/regulator_disable() calls, the 'enable_count' won't be touched and 'regulator_put()' will print a warning. The condition could be made to check if 'enable_count >= 1', and the behavior would be the same, but it's probably a good idea not to touch this refcount if isn't 1.
The only disadvantage to this approach, is that it changes the order in the drivers in which the register_disable() gets called, with respect to other steps in the probe/remove order. With this, the register_disable() will be called right before the consumer reference is free'd.
But the other advantage is that regulator_disable() calls can be removed in simple drivers, where the consumer reference has been requested with devm_regulator_get().
References: https://lore.kernel.org/lkml/20170213023249.GA27688@dtor-ws/ https://lkml.org/lkml/2014/2/4/940
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com> Cc: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Alexandru Ardelean <aardelean@deviqon.com> ---
Note: this patch applies indepently of this series: https://lore.kernel.org/lkml/20210625122324.327585-1-aardelean@deviqon.com/
drivers/regulator/devres.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/regulator/devres.c b/drivers/regulator/devres.c index 826c29499d69..1852afc02990 100644 --- a/drivers/regulator/devres.c +++ b/drivers/regulator/devres.c @@ -16,7 +16,12 @@ static void devm_regulator_release(struct device *dev, void *res) { - regulator_put(*(struct regulator **)res); + struct regulator *regulator = *(struct regulator **)res; + + if (regulator->enable_count == 1) + regulator_disable(regulator); + + regulator_put(regulator); } static struct regulator *_devm_regulator_get(struct device *dev, const char *id, -- 2.31.1
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