Re: [PATCH 2/3] PCI/AER: Disable AER service on suspend when IRQ is shared with PME

[Kai-Heng Feng]

On Thu, Sep 29, 2022 at 5:46 AM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
>
> On Wed, Jul 27, 2022 at 09:32:51AM +0800, 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@xxxxxxxxxxxxx/
> > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=216295
> >
> > Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
> > ---
> >  drivers/pci/pcie/aer.c | 23 ++++++++++++++++++++++-
> >  1 file changed, 22 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> > index 7952e5efd6cf3..60cc373754af2 100644
> > --- a/drivers/pci/pcie/aer.c
> > +++ b/drivers/pci/pcie/aer.c
> > @@ -1372,6 +1372,26 @@ 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);
> > +
> > +     if (dev->shared_pme_irq)
> > +             aer_disable_rootport(rpc);
>
> aer_disable_rootport() seems like it might be overkill.  IIUC, what
> we want to do here is disable AER interrupts, which should only
> require clearing ROOT_PORT_INTR_ON_MESG_MASK in PCI_ERR_ROOT_COMMAND.
>
> In addition to clearing ROOT_PORT_INTR_ON_MESG_MASK,
> aer_disable_rootport() traverses the whole hierarchy, clearing
> PCI_EXP_AER_FLAGS (CERE | NFERE | FERE | URRE) in PCI_EXP_DEVCTL.
> I don't think these DEVCTL bits control interrupt generation, so I
> don't know why we need to touch them.
>
> aer_disable_rootport() also clears PCI_ERR_ROOT_STATUS, which I think
> we should not do during suspend either.  We might want to clear it
> on resume (which we already do in pci_restore_state()), but I think
> generally we should preserve error information as long as it doesn't
> cause trouble.
>
> Your thoughts please :)

Sorry for the belated response.

Clearing ROOT_PORT_INTR_ON_MESG_MASK along to disable interrupt can
solve the issue too.
And I agree that the AER information should be preserved too.

Kai-Heng

>
> > +
> > +     return 0;
> > +}
> > +
> > +static int aer_resume(struct pcie_device *dev)
> > +{
> > +     struct aer_rpc *rpc = get_service_data(dev);
> > +
> > +     if (dev->shared_pme_irq)
> > +             aer_enable_rootport(rpc);
> > +
> > +     return 0;
> > +}
> > +
> >  /**
> >   * aer_root_reset - reset Root Port hierarchy, RCEC, or RCiEP
> >   * @dev: pointer to Root Port, RCEC, or RCiEP
> > @@ -1441,8 +1461,9 @@ static struct pcie_port_service_driver aerdriver = {
> >       .name           = "aer",
> >       .port_type      = PCIE_ANY_PORT,
> >       .service        = PCIE_PORT_SERVICE_AER,
> > -
> >       .probe          = aer_probe,
> > +     .suspend        = aer_suspend,
> > +     .resume         = aer_resume,
> >       .remove         = aer_remove,
> >  };
> >
> > --
> > 2.36.1
> >