Re: [PATCH 1/1] regulator: Only enable disabled regulators on resume

[Javier Martinez Canillas <javier.martinez@collabora.co.uk>]

Hello Doug,

On 03/03/2015 08:05 PM, Javier Martinez Canillas wrote:
> On 03/03/2015 06:24 PM, Doug Anderson wrote:
>>>
>>> diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
>>> index f2452148c8da..8551400d57e4 100644
>>> --- a/drivers/regulator/core.c
>>> +++ b/drivers/regulator/core.c
>>> @@ -3816,9 +3816,11 @@ int regulator_suspend_finish(void)
>>>         list_for_each_entry(rdev, &regulator_list, list) {
>>>                 mutex_lock(&rdev->mutex);
>>>                 if (rdev->use_count > 0  || rdev->constraints->always_on) {
>>> -                       error = _regulator_do_enable(rdev);
>>> -                       if (error)
>>> -                               ret = error;
>>> +                       if (!_regulator_is_enabled(rdev)) {
>> 
>> Looking at _regulator_enable() I see that _regulator_is_enabled()
>> could return an error.  Should we be checking?  Maybe we should have a
>> helper function called by both callers?
>>
> 
> Thanks for pointing that out. I'll change it on v2 as well.
> 

Looking at the code now I remember why I didn't checked for an error
in _regulator_is_enable(), sorry I wrote the patch months ago.

The thing is that _regulator_is_enabled() used to return -EINVAL if
the rdev didn't have an .is_enabled callback but that changed in
commit 9a7f6a4c6edc8 ("regulator: Assume regulators are enabled if
they don't report anything") and now returns 1 in that case. But
_regulator_enable() was not changed and is still checking for -EINVAL
which seems to me like a left over after the mentioned commit.

Also, _regulator_enable() is the only place that has a check for a
negative errno value returned by _regulator_is_enabled().

All other functions calling _regulator_is_enabled() seems to assume
that a return value != 0 means that the regulator is enabled.

Is true though that the rdev .is_enabled callback function may return
an error so I don't know if all those callers are missing a check or
if it's a design decision to assume that a regulator should be enabled
if the actual hardware state can't be obtained.

Best regards,
Javier