linux-kernel - Re: [PATCH v3 20/24] pmdomain: core: Default to use of_genpd_sync

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Message-ID: <CAPDyKFo+8fw0GrFOazekXrb0zNsRkhzVmbOg45YZU+T2dm_SJg@mail.gmail.com>
Date: Tue, 30 Sep 2025 13:33:02 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Saravana Kannan <saravanak@...gle.com>, Jon Hunter <jonathanh@...dia.com>
Cc: 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>, 
	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>, 
	Hiago De Franco <hiago.franco@...adex.com>, Geert Uytterhoeven <geert@...ux-m68k.org>, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH v3 20/24] pmdomain: core: Default to use
 of_genpd_sync_state() for genpd providers

On Fri, 26 Sept 2025 at 17:32, Jon Hunter <jonathanh@...dia.com> wrote:
>
>
> On 25/09/2025 23:31, Saravana Kannan wrote:
>
> ...
>
> >> I have been doing more testing and do see a lot of "tegra-bpmp bpmp:
> >> sync_state() pending due to" on our platforms for basically are driver
> >> that is built as a module.
> >
> > It being "built as a module" is not reason enough for this warning to
> > happen though. One of the main points of fw_devlink is for things to
> > work just as well with modules.
> >
> > In this particular system, do you never plan to load the modules? Or
> > is the module load just missing this timeout by a few seconds or
> > something?
>
> We absolutely do load the drivers. Initially, I observed cases where
> drivers are missing, but doing more testing with the necessary drivers
> present, I still see such messages. A lot of our test infrastructure is
> set up to use NFS for mounting to the rootfs and so I am wondering if
> that can also be a factor?
>
> > If these can be turned off, why not turn these off using the sysfs
> > file or the timeout commandline option to turn them off? You are
> > burning power by leaving these on. A warning seems appropriate to me.
>
> Again the drivers get loaded, so that shouldn't be the case.
>

I realized that we also have an orthogonal, but related problem.

In fact, the genpd in question actually may already have been
powered-off, completely defeating the purpose of the printed warning
that we are discussing.

In genpd we enable the ->sync_state() support, no matter whether the
genpd is powered-on or powered-off at initialization. Although, it's
only when a genpd is powered-on at init, when we prevent it from being
powered-off until the ->sync_state() callback gets invoked. Ideally,
we should be able to skip enabling the ->sync_state() support for
genpd in these cases, possibly silencing some of these prints. I will
have a look at this and get back to you.

Kind regards
Uffe