linux-kernel - Re: [PATCH v19 06/10] power: reset: Add psci-reboot-mode driver

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Message-ID: <CAMRc=MdNfW9pafvWy8L5iv5StR1b4_jghL7j-08cyPZVeO1Mag@mail.gmail.com>
Date: Tue, 6 Jan 2026 16:06:58 +0100
From: Bartosz Golaszewski <brgl@...nel.org>
To: Shivendra Pratap <shivendra.pratap@....qualcomm.com>
Cc: Lorenzo Pieralisi <lpieralisi@...nel.org>, Arnd Bergmann <arnd@...db.de>, 
	Bjorn Andersson <andersson@...nel.org>, Sebastian Reichel <sre@...nel.org>, Rob Herring <robh@...nel.org>, 
	Sudeep Holla <sudeep.holla@....com>, Souvik Chakravarty <Souvik.Chakravarty@....com>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Andy Yan <andy.yan@...k-chips.com>, 
	John Stultz <john.stultz@...aro.org>, Matthias Brugger <matthias.bgg@...il.com>, 
	Moritz Fischer <moritz.fischer@...us.com>, Mark Rutland <mark.rutland@....com>, 
	Conor Dooley <conor+dt@...nel.org>, Konrad Dybcio <konradybcio@...nel.org>, 
	Florian Fainelli <florian.fainelli@...adcom.com>, Krzysztof Kozlowski <krzk@...nel.org>, 
	Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>, 
	Mukesh Ojha <mukesh.ojha@....qualcomm.com>, Andre Draszik <andre.draszik@...aro.org>, 
	Kathiravan Thirumoorthy <kathiravan.thirumoorthy@....qualcomm.com>, linux-pm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org, 
	Srinivas Kandagatla <srini@...nel.org>
Subject: Re: [PATCH v19 06/10] power: reset: Add psci-reboot-mode driver

On Tue, Jan 6, 2026 at 3:45 PM Shivendra Pratap
<shivendra.pratap@....qualcomm.com> wrote:
>
> On 1/6/2026 6:04 PM, Bartosz Golaszewski wrote:
> > On Mon, Jan 5, 2026 at 7:06 PM Shivendra Pratap
> > <shivendra.pratap@....qualcomm.com> wrote:
> >>
> >>>> +static int __init psci_reboot_mode_init(void)
> >>>> +{
> >>>> +       struct faux_device *fdev;
> >>>> +
> >>>> +       fdev = faux_device_create("psci-reboot-mode", NULL, &psci_reboot_mode_ops);
> >>>> +       if (!fdev)
> >>>> +               return -ENODEV;
> >>>
> >>> This will always create this device for everyone who includes this
> >>> module. Move the of_find_compatible_node(NULL, NULL, "arm,psci-1.0")
> >>> call from probe() here instead and don't create the device if it
> >>> fails.
> >>
> >> Ack.
> >> Will move both calls to init before creating the faux device.
> >>
> >> psci_np = of_find_compatible_node(NULL, NULL, "arm,psci-1.0");
> >> and
> >> np = of_find_node_by_name(psci_np, "reboot-mode");
> >> --
> >>
> >
> > On a second glance - and I may be totally wrong - would it be possible
> > to switch to using the auxiliary bus and create this device from
> > drivers/firmware/psci/psci.c? That would be even cleaner.
>
> Till v17, device was being created in psci.c. Lorenzo wanted to move it
> outside psci similar to design of cpuidle-psci.
>
> https://lore.kernel.org/all/aRIfc9iuC2b9DqI+@lpieralisi/
>

Thanks for the link. Right, there's no actual psci driver binding to a
struct device, rather we only have a set of functions called very
early into the boot process.

Nevermind this comment

Bart