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

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Message-ID: <CAGETcx-HnLZBZmP0CUhuYc8jtyAaP6Ax_h0oHubyaL9qw=dF3w@mail.gmail.com>
Date: Fri, 12 Sep 2025 11:32:10 -0700
From: Saravana Kannan <saravanak@...gle.com>
To: Diederik de Haas <didi.debian@...ow.org>
Cc: Geert Uytterhoeven <geert@...ux-m68k.org>, Ulf Hansson <ulf.hansson@...aro.org>, 
	Heiko Stuebner <heiko@...ech.de>, "Rafael J . Wysocki" <rafael@...nel.org>, 
	Tomi Valkeinen <tomi.valkeinen@...asonboard.com>, Thierry Reding <thierry.reding@...il.com>, 
	Sebastian Reichel <sebastian.reichel@...labora.com>, Jonathan Hunter <jonathanh@...dia.com>, 
	linux-rockchip@...ts.infradead.org, Konrad Dybcio <konradybcio@...nel.org>, 
	Peng Fan <peng.fan@....nxp.com>, linux-pm@...r.kernel.org, 
	Johan Hovold <johan@...nel.org>, Sebin Francis <sebin.francis@...com>, 
	Michal Simek <michal.simek@....com>, linux-arm-kernel@...ts.infradead.org, 
	Maulik Shah <maulik.shah@....qualcomm.com>, Stephen Boyd <sboyd@...nel.org>, 
	Bjorn Andersson <andersson@...nel.org>, Christian Hewitt <christianshewitt@...il.com>, 
	linux-kernel@...r.kernel.org, Abel Vesa <abel.vesa@...aro.org>, 
	Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
Subject: Re: [PATCH 0/5] pmdomain: Restore behaviour for disabling unused PM domains

On Thu, Sep 11, 2025 at 1:26 AM Diederik de Haas <didi.debian@...ow.org> wrote:
>
> Hi Geert,
>
> On Thu Sep 11, 2025 at 9:18 AM CEST, Geert Uytterhoeven wrote:
> > 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.
>
> I don't think I fully understand this (not your problem due to lack of
> knowledge on my part), but you mentioning 'fw_devlink' rang a bell.
>
> Some time ago Nicolas Frattaroli and I worked on an image for PINE64's
> *Quartz* devices and that added ``fw_devlink=off`` to cmdline.
> I've been using it on all my Rockchip based devices, without
> understanding that parameter ... but (apparently) on my 'rock64-test'
> device, where I tested it with, I had removed that parameter.
> Putting that parameter back ... and those warnings are gone!
>
> Thanks a LOT for that hint!

Please don't just disable fw_devlink using fw_devlink=off. We want to
fix any issues you are hitting with it. I might even delete this "off"
option sometime. It was meant as an early debug option.

Thanks,
Saravana