On Fri, Feb 17, 2023 at 4:01 PM Christian Kohlschütter <christian@xxxxxxxxxxxxxxxx> wrote: > > On 18. Feb 2023, at 00:46, Saravana Kannan <saravanak@xxxxxxxxxx> wrote: > > > > On Fri, Feb 17, 2023 at 3:33 PM Christian Kohlschütter > > <christian@xxxxxxxxxxxxxxxx> wrote: > >> > >> 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/ > > > > I did read the write up before I sent my request. I'm asking for > > specifics on which functions in the set_machine_constraints() was > > causing the issue. And it's also a bit unclear to me if the issue was > > with having stuff called twice on the alway-on regulator or the > > supply. > > > > -Saravana > > I'm afraid I cannot give a more detailed answer than what's in the write up and the previous discussion on this mailing list; I thought it's pretty detailed already. Well, I do my best not to break your use case with whatever info you are willing to provide. We'll figure it out one way or another I suppose. > However, it should be relatively straightforward to reproduce the issue. If one has the hardware. Which I don't. -Saravana
