linux-kernel - Re: [PATCH 0/5] pmdomain: Restore behaviour for disabling unused PM domains

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Message-ID: <CAMuHMdVxjOLZsas4+nmAkZjbJsQjxdkZvZ8tTY9pq2zz3gvFNQ@mail.gmail.com>
Date: Thu, 11 Sep 2025 09:18:31 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Diederik de Haas <didi.debian@...ow.org>
Cc: Ulf Hansson <ulf.hansson@...aro.org>, 
	Nicolas Frattaroli <nicolas.frattaroli@...labora.com>, Saravana Kannan <saravanak@...gle.com>, 
	linux-pm@...r.kernel.org, Stephen Boyd <sboyd@...nel.org>, 
	"Rafael J . Wysocki" <rafael@...nel.org>, Heiko Stuebner <heiko@...ech.de>, 
	Sebastian Reichel <sebastian.reichel@...labora.com>, Sebin Francis <sebin.francis@...com>, 
	Bjorn Andersson <andersson@...nel.org>, Abel Vesa <abel.vesa@...aro.org>, 
	Peng Fan <peng.fan@....nxp.com>, Tomi Valkeinen <tomi.valkeinen@...asonboard.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-rockchip@...ts.infradead.org, 
	Christian Hewitt <christianshewitt@...il.com>
Subject: Re: [PATCH 0/5] pmdomain: Restore behaviour for disabling unused PM domains

Hi Diederik,

On Wed, 10 Sept 2025 at 21:33, Diederik de Haas <didi.debian@...ow.org> wrote:
> On Tue Sep 9, 2025 at 1:11 PM CEST, Ulf Hansson wrote:
> > Recent changes to genpd prevents those PM domains being powered-on during
> > initialization from being powered-off during the boot sequence. Based upon
> > whether CONFIG_PM_CONFIG_PM_GENERIC_DOMAINS_OF is set of not, genpd relies
> > on the sync_state mechanism or the genpd_power_off_unused() (which is a
> > late_initcall_sync), to understand when it's okay to allow these PM domains
> > to be powered-off.
> >
> > This new behaviour in genpd has lead to problems on different platforms [1].
> >
> > In this series, I am therefore suggesting to restore the behavior of
> > genpd_power_off_unused() along with introducing a new genpd config flag,
> > GENPD_FLAG_NO_STAY_ON, to allow genpd OF providers to opt-out from the new
> > behaviour.
>
> Is it expected that I'm still seeing this on a Rock64 (rk3328), just
> like before [1]?
>
>   [   17.124202] rockchip-pm-domain ff100000.syscon:power-controller: sync_state() pending due to ff300000.gpu
>   [   17.129799] rockchip-pm-domain ff100000.syscon:power-controller: sync_state() pending due to ff350000.video-codec
>   [   17.140003] rockchip-pm-domain ff100000.syscon:power-controller: sync_state() pending due to ff360000.video-codec

Yes, as the sync state is still blocked on them.
Disabling unused PM Domains is done independently of sync state.

> This is with a 6.17-rc5 kernel with this patch set applied.
> And it also has this patch from Christian Hewitt added, now in v3:
> https://lore.kernel.org/linux-rockchip/20250906120810.1833016-1-christianshewitt@gmail.com/
>
> When I boot into a 6.17-rc5 kernel without any patches applied, I do get
> the 2 for ff350000.video-codec and ff360000.video-codec, but not the
> ff300000.gpu one.
>
> Interestingly:
> ff300000.gpu -> power-domains = <&power RK3328_PD_GPU>;
> ff350000.video-codec -> power-domains = <&power RK3328_PD_VPU>;
> ff360000.video-codec -> power-domains = <&power RK3328_PD_VIDEO>;
>
> I would be surprised if that was a coincidence.

Fw_devlinks ignores the index cell (RK3328_PD_*), hence all links are
created pointing to the pmdomain controller (in case it has a platform
driver) or the first pmdomain (in case it has not). thus blocking the
sync state call and power-down for _all_ pmdomains managed by the
controller.

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