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SubjectRe: [PATCH v3 4/4] regulator: core: Balance coupled regulators voltages
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On 12/12/2017 12:54 PM, Mark Brown wrote:
> On Thu, Dec 07, 2017 at 10:46:15AM +0100, Maciej Purski wrote:
>
>> @@ -2447,10 +2482,9 @@ static int _regulator_is_enabled(struct regulator_dev *rdev)
>> return rdev->desc->ops->is_enabled(rdev);
>> }
>>
>> -static int _regulator_list_voltage(struct regulator *regulator,
>> - unsigned selector, int lock)
>> +static int _regulator_list_voltage(struct regulator_dev *rdev,
>> + unsigned selector, int lock)
>> {
>
> Please split this refactoring of _list_voltage() into a separate patch
> for ease of review. It can go in separately which will make this change
> smaller and easier to review.
>
>> @@ -2928,6 +2961,35 @@ static int regulator_set_voltage_unlocked(struct regulator *regulator,
>> if (ret < 0)
>> goto out2;
>>
>> + /*
>> + * If the regulator is not coupled just set voltage normally, else
>> + * return after changing consumer demands without changing voltage.
>> + * This will be handled outside the function
>> + * by regulator_balance_coupled()
>> + */
>> + if (!rdev->coupling_desc) {
>> + ret = regulator_set_voltage_rdev(regulator->rdev,
>> + min_uV, max_uV);
>> + if (ret < 0)
>> + goto out2;
>> + }
>
> As I think I said on the previous version I'm not enthusiastic about
> having two separate code paths for setting the voltage, it makes it much
> more likely that things will break especially given how rare coupled
> regulators are. It would be cleaner to make uncoupled regulators just
> be a special case of coupled regulators, that way more of the code is
> shared. To that end I'd adjust the code so that we always have a
> coupling descriptor and then handle the case where there's only one
> regulator described in there.
>

Do you have any suggestion, how should I implement that path? The thing which
makes it more complicated is locking, because set_voltage_unlocked is done under
one regulator's mutex and its suppliers, while balance procedure locks every
coupled regulator without its suppliers. The suppliers for a single regulator
are locked when setting a single regulator's voltage takes place.

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