linux-kernel - Re: [PATCH v4 5/5] power: sequencing: Add the Power Sequencing driver for the PCIe M.2 connectors

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Message-ID: <pqix44ld4icxhmvaranezas7j77wcrmkfpj4xyxgxir3tmfwx7@fswnr25k2f43>
Date: Wed, 7 Jan 2026 18:01:56 +0530
From: Manivannan Sadhasivam <mani@...nel.org>
To: Bartosz Golaszewski <brgl@...nel.org>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>, 
	Bjorn Helgaas <bhelgaas@...gle.com>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Damien Le Moal <dlemoal@...nel.org>, Niklas Cassel <cassel@...nel.org>, 
	Linus Walleij <linus.walleij@...aro.org>, linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-arm-msm@...r.kernel.org, 
	Stephan Gerhold <stephan.gerhold@...aro.org>, Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>, 
	linux-pm@...r.kernel.org, linux-ide@...r.kernel.org
Subject: Re: [PATCH v4 5/5] power: sequencing: Add the Power Sequencing
 driver for the PCIe M.2 connectors

On Wed, Jan 07, 2026 at 10:51:11AM +0100, Bartosz Golaszewski wrote:
> On Wed, Jan 7, 2026 at 10:39 AM Manivannan Sadhasivam <mani@...nel.org> wrote:
> >
> > > > +
> > > > +static int pwrseq_pcie_m2_probe(struct platform_device *pdev)
> > > > +{
> > > > +       struct device *dev = &pdev->dev;
> > > > +       struct pwrseq_pcie_m2_ctx *ctx;
> > > > +       struct pwrseq_config config = {};
> > > > +       int ret;
> > > > +
> > > > +       ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
> > > > +       if (!ctx)
> > > > +               return -ENOMEM;
> > > > +
> > > > +       ctx->of_node = dev_of_node(dev);
> > >
> > > Since you're storing the node address for later, I'd suggest using
> > > of_node_get() to get a real reference.
> > >
> >
> > If CONFIG_OF_DYNAMIC is not enabled, then of_node_get() will just return the
> > passed pointer. I always prefer using dev_of_node() since it has the CONFIG_OF
> > and NULL check. Though, the checks won't apply here, I used it for consistency.
> >
> 
> I think it's just more of a good practice to take a reference to any
> resource whenever you store keep it for longer than the duration of
> the function even if the actual reference counting is disabled in some
> instances.

Good practice you inherited from writing Rust code :)

> If ever we switch to fwnodes, the circumstances may be
> different than static devicetree.
> 
> You can also do "ctx->of_node = of_node_get(dev_of_node(dev));", all
> the NULL-checks are there.
> 

This may not be needed. I can use of_node_get() here, but the APIs are just
fragile such that neither dev_of_node() nor of_node_get() increments the
refcount always.

- Mani

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