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

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Message-ID: <CAMuHMdVit2WtjmFUHctBjndAo33Dibsg-GrOyFj98==gxk5rEw@mail.gmail.com>
Date: Tue, 24 Jun 2025 14:10:34 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Ulf Hansson <ulf.hansson@...aro.org>
Cc: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>, 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, 
	Linux-Renesas <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH v2 00/21] pmdomain: Add generic ->sync_state() support to genpd

On Mon, 23 Jun 2025 at 17:06, Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> On Mon, 23 Jun 2025 at 16:21, Ulf Hansson <ulf.hansson@...aro.org> wrote:
> > On Thu, 19 Jun 2025 at 13:40, Ulf Hansson <ulf.hansson@...aro.org> wrote:
> > > 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?
> >
> > I did some investigation around this and found that both
> > drivers/pmdomain/renesas/rcar-gen4-sysc.c and
> > drivers/pmdomain/renesas/rcar-sysc.c are registering their genpd
> > providers at the early_initcall() level.
> >
> > I was trying to find (by browsing renesas DTSes and looking into
> > drivers) if there is any consumers that actually relies on this, but
> > so far the earliest consumer I have found is the
> > drivers/irqchip/irq-renesas-irqc.c, but that's at postcore_initcall().
> > Of course, it's difficult to say if my analysis is complete as there
> > are a lot of platform variants and I didn't check them all.
> >
> > Maybe we should just give it a try and move both two drivers above to
> > postcore_initcall and see if it works (assuming the irq-renesas-irqc
> > supports -EPROBE_DEFER correctly too).
> >
> > If this doesn't work, I think we need to find a way to allow deferring
> > the call to device_add() in of_genpd_provider_add*() for genpd
> > provider's devices.
>
> Commit dcc09fd143bb97c2 ("soc: renesas: rcar-sysc: Add DT support for
> SYSC PM domains") explains:
>
>    "Initialization is done from an early_initcall(), to make sure the PM
>     Domains are initialized before secondary CPU bringup."
>
> but that matters only for arm32 systems (R-Car Gen1 and Gen2).
> Arm64 systems (R-Car Gen3 and Gen4) use PSCI for CPU PM Domain control.

[...]

> As expected, there is no impact on R-Car H3 ES2.0.
> I will test on R-Car V4M tomorrow, but expect no issues.

R-Car V4M is fine, too.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds