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

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Message-Id: <DCPTTD0NKOE6.1HKQ87ESFOT6D@cknow.org>
Date: Thu, 11 Sep 2025 10:26:03 +0200
From: "Diederik de Haas" <didi.debian@...ow.org>
To: "Geert Uytterhoeven" <geert@...ux-m68k.org>
Cc: "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>, "Saravana Kannan" <saravanak@...gle.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

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!

Groetjes,
  Diederik

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