Re: [PATCH v5] regulator: core: Resolve supply name earlier to prevent double-init

[Christian Kohlschütter]

On 18. Feb 2023, at 00:22, Saravana Kannan <saravanak@xxxxxxxxxx> wrote:
> 
> On Thu, Aug 25, 2022 at 2:28 PM Christian Kohlschütter
> <christian@xxxxxxxxxxxxxxxx> wrote:
>> 
>> Previously, an unresolved regulator supply reference upon calling
>> regulator_register on an always-on or boot-on regulator caused
>> set_machine_constraints to be called twice.
>> 
>> This in turn may initialize the regulator twice, leading to voltage
>> glitches that are timing-dependent. A simple, unrelated configuration
>> change may be enough to hide this problem, only to be surfaced by
>> chance.
> 
> In your case, can you elaborate which part of the constraints/init
> twice caused the issue?
> 
> I'm trying to simplify some of the supply resolving code and I'm
> trying to not break your use case.
> 
> -Saravana

Here's a write-up of my use case, and how we got to the solution:
https://kohlschuetter.github.io/blog/posts/2022/10/28/linux-nanopi-r4s/