linux-kernel - Re: [PATCH v8 1/3] PCI: Add helper to check if any of ancestor device support D3cold

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Message-ID: <CAAd53p7e5dWEsSdrvpZ_5b9LLrhVwQEChUkFityN_nOuT2K=zQ@mail.gmail.com>
Date: Thu, 25 Apr 2024 14:26:34 +0800
From: Kai-Heng Feng <kai.heng.feng@...onical.com>
To: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
Cc: bhelgaas@...gle.com, mahesh@...ux.ibm.com, oohall@...il.com, 
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linuxppc-dev@...ts.ozlabs.org, bagasdotme@...il.com, 
	regressions@...ts.linux.dev, linux-nvme@...ts.infradead.org, kch@...dia.com, 
	hch@....de, gloriouseggroll@...il.com, kbusch@...nel.org, sagi@...mberg.me, 
	hare@...e.de
Subject: Re: [PATCH v8 1/3] PCI: Add helper to check if any of ancestor device
 support D3cold

On Thu, Apr 18, 2024 at 9:15 AM Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@...ux.intel.com> wrote:
>
>
> On 4/15/24 9:32 PM, Kai-Heng Feng wrote:
> > In addition to nearest upstream bridge, driver may want to know if the
> > entire hierarchy can be powered off to perform different action.
> >
> > So walk higher up the hierarchy to find out if any device has valid
> > _PR3.
> >
> > The user will be introduced in next patch.
> >
> > Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> > ---
>
> Since it has been a while, I was not sure what this series is about.
>
> IMO, it is better to include a cover letter with the summary of your
> changes.

OK, will do in next revision.

>
>
> > v8:
> >  - No change.
> >
> >  drivers/pci/pci.c   | 16 ++++++++++++++++
> >  include/linux/pci.h |  2 ++
> >  2 files changed, 18 insertions(+)
> >
> > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > index e5f243dd4288..7a5662f116b8 100644
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -6225,6 +6225,22 @@ bool pci_pr3_present(struct pci_dev *pdev)
> >               acpi_has_method(adev->handle, "_PR3");
> >  }
> >  EXPORT_SYMBOL_GPL(pci_pr3_present);
> > +
> > +bool pci_ancestor_pr3_present(struct pci_dev *pdev)
> > +{
> > +     struct pci_dev *parent = pdev;
> > +
> > +     if (acpi_disabled)
> > +             return false;
> > +
> > +     while ((parent = pci_upstream_bridge(parent))) {
> > +             if (pci_pr3_present(pdev))
>
> I think it should be "parent" here?

Thanks for catching this.

But this patch will be dropped in next version for better simplicity.

Kai-Heng

>
> > +                     return true;
> > +     }
> > +
> > +     return false;
> > +}
> > +EXPORT_SYMBOL_GPL(pci_ancestor_pr3_present);
> >  #endif
> >
> >  /**
> > diff --git a/include/linux/pci.h b/include/linux/pci.h
> > index 16493426a04f..cd71ebfd0f89 100644
> > --- a/include/linux/pci.h
> > +++ b/include/linux/pci.h
> > @@ -2620,10 +2620,12 @@ struct irq_domain *pci_host_bridge_acpi_msi_domain(struct pci_bus *bus);
> >  void
> >  pci_msi_register_fwnode_provider(struct fwnode_handle *(*fn)(struct device *));
> >  bool pci_pr3_present(struct pci_dev *pdev);
> > +bool pci_ancestor_pr3_present(struct pci_dev *pdev);
> >  #else
> >  static inline struct irq_domain *
> >  pci_host_bridge_acpi_msi_domain(struct pci_bus *bus) { return NULL; }
> >  static inline bool pci_pr3_present(struct pci_dev *pdev) { return false; }
> > +static inline bool pci_ancestor_pr3_present(struct pci_dev *pdev) { return false; }
> >  #endif
> >
> >  #ifdef CONFIG_EEH
>
> --
> Sathyanarayanan Kuppuswamy
> Linux Kernel Developer
>