linux-kernel - Re: [PATCH v5 1/4] PCI/portdrv: Make use of pci_dev::bridge

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Message-ID: <CAJZ5v0hw7C2dHC3yXAwya-KAjzYxU+QgavO_MkR9Rscsm_YHvg@mail.gmail.com>
Date: Fri, 2 Aug 2024 13:19:24 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Lukas Wunner <lukas@...ner.de>, manivannan.sadhasivam@...aro.org
Cc: Bjorn Helgaas <bhelgaas@...gle.com>, "Rafael J. Wysocki" <rafael@...nel.org>, Len Brown <lenb@...nel.org>, 
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-acpi@...r.kernel.org, mika.westerberg@...ux.intel.com, 
	Hsin-Yi Wang <hsinyi@...omium.org>
Subject: Re: [PATCH v5 1/4] PCI/portdrv: Make use of pci_dev::bridge_d3 for
 checking the D3 possibility

On Fri, Aug 2, 2024 at 11:49 AM Lukas Wunner <lukas@...ner.de> wrote:
>
> On Fri, Aug 02, 2024 at 11:25:00AM +0530, Manivannan Sadhasivam via B4 Relay wrote:
> > PCI core is already caching the value of pci_bridge_d3_possible() in
> > pci_dev::bridge_d3 during pci_pm_init(). Since the value is not going to
> > change,

Is that really the case?

Have you seen pci_bridge_d3_update()?

> let's make use of the cached value.
> [...]
> > --- a/drivers/pci/pcie/portdrv.c
> > +++ b/drivers/pci/pcie/portdrv.c
> > @@ -702,7 +702,7 @@ static int pcie_portdrv_probe(struct pci_dev *dev,
> >       dev_pm_set_driver_flags(&dev->dev, DPM_FLAG_NO_DIRECT_COMPLETE |
> >                                          DPM_FLAG_SMART_SUSPEND);
> >
> > -     if (pci_bridge_d3_possible(dev)) {
> > +     if (dev->bridge_d3) {
>
> I don't know if there was a reason to call pci_bridge_d3_possible()
> (instead of using the cached value) on probe, remove and shutdown.
>
> The change is probably safe but it would still be good to get some
> positive test results with Thunderbolt laptops etc to raise the
> confidence.

If I'm not mistaken, the change is not correct.