linux-kernel - Re: [PATCH v2] clk: tegra: Adjust callbacks in tegra_clock

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Message-ID: <176859039010.168755.11485202766941795981.b4-ty@nvidia.com>
Date: Fri, 16 Jan 2026 20:06:37 +0100
From: Thierry Reding <thierry.reding@...il.com>
To: Jon Hunter <jonathanh@...dia.com>,
	Linux PM <linux-pm@...r.kernel.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>
Cc: linux-tegra@...r.kernel.org,
	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 v2] clk: tegra: Adjust callbacks in tegra_clock_pm

From: Thierry Reding <treding@...dia.com>


On Tue, 06 Jan 2026 13:19:47 +0100, Rafael J. Wysocki wrote:
> On Tuesday, January 6, 2026 1:07:15 PM CET Rafael J. Wysocki wrote:
> > 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.
> 
> [...]

Applied, thanks!

[1/1] clk: tegra: Adjust callbacks in tegra_clock_pm
      commit: 53bf300fd4a73146882889020504e8e87cc86c7d

Best regards,
-- 
Thierry Reding <treding@...dia.com>