linux-kernel - Re: [PATCH v2 00/21] pmdomain: Add generic ->sync

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Message-ID: <CAPDyKFpprO=HGuiHX3MQ_+m1YRnaWG=XwCx8-fSdXak8VBDUbQ@mail.gmail.com>
Date: Thu, 19 Jun 2025 13:40:57 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>, 
	Geert Uytterhoeven <geert+renesas@...der.be>
Cc: Saravana Kannan <saravanak@...gle.com>, Stephen Boyd <sboyd@...nel.org>, linux-pm@...r.kernel.org, 
	"Rafael J . Wysocki" <rafael@...nel.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	Michael Grzeschik <m.grzeschik@...gutronix.de>, Bjorn Andersson <andersson@...nel.org>, 
	Abel Vesa <abel.vesa@...aro.org>, Peng Fan <peng.fan@....nxp.com>, 
	Johan Hovold <johan@...nel.org>, Maulik Shah <maulik.shah@....qualcomm.com>, 
	Michal Simek <michal.simek@....com>, Konrad Dybcio <konradybcio@...nel.org>, 
	Thierry Reding <thierry.reding@...il.com>, Jonathan Hunter <jonathanh@...dia.com>, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 00/21] pmdomain: Add generic ->sync_state() support to genpd

On Fri, 13 Jun 2025 at 12:33, Tomi Valkeinen
<tomi.valkeinen@...asonboard.com> wrote:
>
> Hi Ulf,
>
> On 23/05/2025 16:39, Ulf Hansson wrote:
> > Changes in v2:
> >       - Well, quite a lot as I discovered various problems when doing
> >       additional testing of corner-case. I suggest re-review from scratch,
> >       even if I decided to keep some reviewed-by tags.
> >       - Added patches to allow some drivers that needs to align or opt-out
> >       from the new common behaviour in genpd.
> >
> > If a PM domain (genpd) is powered-on during boot, there is probably a good
> > reason for it. Therefore it's known to be a bad idea to allow such genpd to be
> > powered-off before all of its consumer devices have been probed. This series
> > intends to fix this problem.
> >
> > We have been discussing these issues at LKML and at various Linux-conferences
> > in the past. I have therefore tried to include the people I can recall being
> > involved, but I may have forgotten some (my apologies), feel free to loop them
> > in.
> >
> > I have tested this with QEMU with a bunch of local test-drivers and DT nodes.
> > Let me know if you want me to share this code too.
> >
> > Please help review and test!
>
> I tested this Renesas white-hawk board, and it hangs at boot. With
> earlycon, I captured with/without boot logs, attached.
>
> The hang case doesn't look very healthy with all these: "kobject:
> '(null)' ((____ptrval____)): is not initialized, yet kobject_get() is
> being called."

Tomi, thanks a lot for helping out with testing!

rcar_gen4_sysc_pd_init() calls pm_genpd_init() and
of_genpd_add_provider_onecell().

rcar_gen4_sysc_pd_init() is an early_initcall, which I guess is the
reason for these problems, as the genpd_provider_bus has not been
registered that early (it's done at core_initcall)

Do you think it would be possible to move rcar_gen4_sysc_pd_init() to
a postcore/arch_initcall?

Kind regards
Uffe