linux-kernel - Re: [PATCH v1] clk: tegra: Adjust callbacks in tegra_clock

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Message-ID: <CAJZ5v0i7Rbk5sWCo2Z1Y4j_ZFW7nCUr18H8i2JCM=aPpfZOQ4w@mail.gmail.com>
Date: Tue, 6 Jan 2026 13:07:15 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Jon Hunter <jonathanh@...dia.com>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, linux-tegra@...r.kernel.org, 
	Linux PM <linux-pm@...r.kernel.org>, Peter De Schrijver <pdeschrijver@...dia.com>, 
	Prashant Gaikwad <pgaikwad@...dia.com>, Michael Turquette <mturquette@...libre.com>, 
	Stephen Boyd <sboyd@...nel.org>, Thierry Reding <thierry.reding@...il.com>, linux-clk@...r.kernel.org, 
	LKML <linux-kernel@...r.kernel.org>, Dmitry Osipenko <digetx@...il.com>, 
	Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH v1] clk: tegra: Adjust callbacks in tegra_clock_pm

Hi Jon,

On Tue, Jan 6, 2026 at 11:36 AM Jon Hunter <jonathanh@...dia.com> wrote:
>
> Hi Rafael,
>
> On 04/01/2026 11:53, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> >
> > System suspend and resume callbacks run after the core has bumped
> > up the runtime PM usage counters of all devices, so these callbacks
> > need not worry about runtime PM reference counting.
> >
> > Accordingly, to eliminate useless overhead related to runtime PM
> > usage counter manipulation, set the suspend callback pointer in
> > tegra_clock_pm to pm_runtime_resume() and do not set the resume
> > callback in it at all.
> >
> > This will also facilitate a planned change of the pm_runtime_put()
> > return type to void in the future.
> >
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > ---
> >
> > This patch is requisite for converting pm_runtime_put() into a void
> > function.
> >
> > If you decide to pick it up, please let me know.
> >
> > Otherwise, an ACK or equivalent will be appreciated, but also the lack
> > of specific criticism will be eventually regarded as consent.
> >
> > ---
> >   drivers/clk/tegra/clk-device.c |    2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > --- a/drivers/clk/tegra/clk-device.c
> > +++ b/drivers/clk/tegra/clk-device.c
> > @@ -175,7 +175,7 @@ unreg_clk:
> >    * perspective since voltage is kept at a nominal level during suspend anyways.
> >    */
> >   static const struct dev_pm_ops tegra_clock_pm = {
> > -     SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_resume_and_get, pm_runtime_put)
> > +     SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_resume, NULL)
> >   };
> >
> >   static const struct of_device_id tegra_clock_match[] = {
>
>
> I gave this a quick test and this is causing a suspend regression on
> Tegra20 and Tegra30 that use this driver. Looking at the console log
> on Tegra20 I see the following errors ...
>
>   tegra-clock tegra_clk_sclk: PM: dpm_run_callback(): pm_runtime_resume returns 1

Of course, it needs a wrapper.

>   tegra-clock tegra_clk_sclk: PM: failed to suspend: error 1
>   PM: Some devices failed to suspend, or early wake event detected

Thanks for reporting!