linux-kernel - Re: [PATCH v5] PCI/PM: Prevent runtime suspend until devices are fully initialized

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Message-ID: <20260122190648.GA37646@bhelgaas>
Date: Thu, 22 Jan 2026 13:06:48 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: Brian Norris <briannorris@...omium.org>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, Lukas Wunner <lukas@...ner.de>,
	linux-pm@...r.kernel.org,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Subject: Re: [PATCH v5] PCI/PM: Prevent runtime suspend until devices are
 fully initialized

On Thu, Jan 22, 2026 at 10:29:50AM -0800, Brian Norris wrote:
> On Thu, Jan 22, 2026 at 07:17:21PM +0100, Rafael J. Wysocki wrote:
> > On Thu, Jan 22, 2026 at 6:49 PM Brian Norris <briannorris@...omium.org> wrote:

> > > @@ -379,6 +380,12 @@ void pci_bus_add_device(struct pci_dev *dev)
> > >                 put_device(&pdev->dev);
> > >         }
> > >
> > > +       /*
> > > +        * Enable runtime PM (and potentially suspend) only after we've fully
> > > +        * configured the PCI state.
> > > +        */
> > 
> > I would make it a bit more precise, something like "Enable runtime PM,
> > which potentially allows the device to suspend immediately, only after
> > the PCI state has been configured completely."

> > > @@ -3196,8 +3196,11 @@ void pci_pm_init(struct pci_dev *dev)
> > >  poweron:
> > >         pci_pm_power_up_and_verify_state(dev);
> > >         pm_runtime_forbid(&dev->dev);
> > > +       /*
> > > +        * Mark ourselves active now, to prevent our parent from suspending
> > > +        * while we finish configuring the PCI device.
> > > +        */
> > 
> > I would rephrase the comment this way:
> > 
> > "Runtime PM will be enabled for the device when it has been fully
> > configured, but since its parent and suppliers may suspend in the
> > meantime, prevent them from doing so by changing the device's runtime
> > PM status to "active"."

Updated both, thanks to both of you!