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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAGETcx9W5MXyHA2r1kDh9=WJiQWLF1xdPaSCH=jXYeAHqQW60w@mail.gmail.com>
Date: Fri, 12 Sep 2025 11:36:35 -0700
From: Saravana Kannan <saravanak@...gle.com>
To: Ulf Hansson <ulf.hansson@...aro.org>
Cc: Geert Uytterhoeven <geert@...ux-m68k.org>, 
	Nicolas Frattaroli <nicolas.frattaroli@...labora.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>, 
	Diederik de Haas <didi.debian@...ow.org>, 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
Subject: Re: [PATCH 0/5] pmdomain: Restore behaviour for disabling unused PM domains

On Tue, Sep 9, 2025 at 4:11 AM Ulf Hansson <ulf.hansson@...aro.org> 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.
>
> Kind regards
> Ulf Hansson
>
> [1]
> https://lore.kernel.org/all/20250701114733.636510-1-ulf.hansson@linaro.org/
> https://lore.kernel.org/all/20250902-rk3576-lockup-regression-v1-1-c4a0c9daeb00@collabora.com/

I'm surprised this is happening. The default behavior of sync_state()
is to never turn off a power domain until all the consumers have
probed.

Is there a consumer that's not captured correctly? If so, can we add them?

Also, there are already sync_state related kernel configs, command
line options and sysfs files that should allow people to power off
devices (at different levels of granularity) even if its consumers
haven't probed.

Thanks,
Saravana

>
> Ulf Hansson (5):
>   pmdomain: core: Restore behaviour for disabling unused PM domains
>   pmdomain: rockchip: Fix regulator dependency with
>     GENPD_FLAG_NO_STAY_ON
>   pmdomain: renesas: rcar-sysc: Don't keep unused PM domains powered-on
>   pmdomain: renesas: rcar-gen4-sysc: Don't keep unused PM domains
>     powered-on
>   pmdomain: renesas: rmobile-sysc: Don't keep unused PM domains
>     powered-on
>
>  drivers/pmdomain/core.c                   | 20 ++++++++++++++------
>  drivers/pmdomain/renesas/rcar-gen4-sysc.c |  1 +
>  drivers/pmdomain/renesas/rcar-sysc.c      |  1 +
>  drivers/pmdomain/renesas/rmobile-sysc.c   |  3 ++-
>  drivers/pmdomain/rockchip/pm-domains.c    |  2 +-
>  include/linux/pm_domain.h                 |  7 +++++++
>  6 files changed, 26 insertions(+), 8 deletions(-)
>
> --
> 2.43.0
>