linux-kernel - Re: [PATCH v3 3/4] PCI/AER: Disable AER interrupt on suspend

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Date:   Fri, 21 Apr 2023 13:32:12 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
Cc:     bhelgaas@...gle.com, mika.westerberg@...ux.intel.com,
        koba.ko@...onical.com, Mahesh J Salgaonkar <mahesh@...ux.ibm.com>,
        "Oliver O'Halloran" <oohall@...il.com>,
        linuxppc-dev@...ts.ozlabs.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/4] PCI/AER: Disable AER interrupt on suspend

On Thu, Apr 20, 2023 at 10:53 PM Sathyanarayanan Kuppuswamy
<sathyanarayanan.kuppuswamy@...ux.intel.com> wrote:
>
>
>
> On 4/20/23 5:59 AM, Kai-Heng Feng wrote:
> > PCIe service that shares IRQ with PME may cause spurious wakeup on
> > system suspend.
> >
> > PCIe Base Spec 5.0, section 5.2 "Link State Power Management" states
> > that TLP and DLLP transmission is disabled for a Link in L2/L3 Ready
> > (D3hot), L2 (D3cold with aux power) and L3 (D3cold), so we don't lose
> > much here to disable AER during system suspend.
> >
> > This is very similar to previous attempts to suspend AER and DPC [1],
> > but with a different reason.
> >
> > [1] https://lore.kernel.org/linux-pci/20220408153159.106741-1-kai.heng.feng@canonical.com/
> > Link: https://bugzilla.kernel.org/show_bug.cgi?id=216295
> >
> > Reviewed-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> > Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> > ---
>
> In Patch #1, you skip clearing AER errors in the resume path, right? So if we disable
> interrupts here, will AER driver not be notified on resume path error?

I agree the driver should report the error via aer_isr_one_error() on
resume path.
But on the system I am using (Intel ADL PCH), once the interrupt is
disabled, PCI_ERR_ROOT_STATUS doesn't record error anymore.
Not sure if it's intended though.

Kai-Heng

>
> > v3:
> >  - No change.
> >
> > v2:
> >  - Only disable AER IRQ.
> >  - No more check on PME IRQ#.
> >  - Use helper.
> >
> >  drivers/pci/pcie/aer.c | 22 ++++++++++++++++++++++
> >  1 file changed, 22 insertions(+)
> >
> > diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> > index 1420e1f27105..9c07fdbeb52d 100644
> > --- a/drivers/pci/pcie/aer.c
> > +++ b/drivers/pci/pcie/aer.c
> > @@ -1356,6 +1356,26 @@ static int aer_probe(struct pcie_device *dev)
> >       return 0;
> >  }
> >
> > +static int aer_suspend(struct pcie_device *dev)
> > +{
> > +     struct aer_rpc *rpc = get_service_data(dev);
> > +     struct pci_dev *pdev = rpc->rpd;
> > +
> > +     aer_disable_irq(pdev);
> > +
> > +     return 0;
> > +}
> > +
> > +static int aer_resume(struct pcie_device *dev)
> > +{
> > +     struct aer_rpc *rpc = get_service_data(dev);
> > +     struct pci_dev *pdev = rpc->rpd;
> > +
> > +     aer_enable_irq(pdev);
> > +
> > +     return 0;
> > +}
> > +
> >  /**
> >   * aer_root_reset - reset Root Port hierarchy, RCEC, or RCiEP
> >   * @dev: pointer to Root Port, RCEC, or RCiEP
> > @@ -1420,6 +1440,8 @@ static struct pcie_port_service_driver aerdriver = {
> >       .service        = PCIE_PORT_SERVICE_AER,
> >
> >       .probe          = aer_probe,
> > +     .suspend        = aer_suspend,
> > +     .resume         = aer_resume,
> >       .remove         = aer_remove,
> >  };
> >
>
> --
> Sathyanarayanan Kuppuswamy
> Linux Kernel Developer