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SubjectRe: [PATCH 1/5] regulator: core: Resolve supply earlier
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On 19/04/16 16:40, Mark Brown wrote:
> * PGP Signed by an unknown key
>
> On Tue, Apr 19, 2016 at 11:16:59AM +0100, Jon Hunter wrote:
>
>> So the following seems to work, but only item I am uncertain about
>> is if it is ok to move the mutex_lock to after the
>> machine_set_constraints()?
>
> We definitely don't need the list to apply constraints to a single
> regulator.
>
>> + mutex_lock(&regulator_list_mutex);
>> +
>> ret = device_register(&rdev->dev);
>> if (ret != 0) {
>> put_device(&rdev->dev);
>> + mutex_unlock(&regulator_list_mutex);
>> goto wash;
>> }
>
> This is *really* weird. Why would we need the list lock to do a
> device_register()?

The device_register() is going to add the regulator to the
regulator class list and this means that after this, someone
could look up that regulator via ...

static struct regulator_dev *of_find_regulator_by_node(struct device_node *np)
{
struct device *dev;

dev = class_find_device(&regulator_class, NULL, np, of_node_match);

return dev ? dev_to_rdev(dev) : NULL;
}

So I did not think that we would want someone to be able to
look-up the regulator via of_find_regulator_by_node() until
it had been registered successfully. In fact I believe that
not locking around device_register() was causing some crashes
when I was testing.

Cheers
Jon

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