Re: [PATCH v2] PCI/AER: Enable SERR# forwarding in non ACPI flow

[poza]

On 2018-09-06 01:40, Bjorn Helgaas wrote:
> On Thu, Aug 09, 2018 at 08:41:27PM +0530, poza@xxxxxxxxxxxxxx wrote:
> > On 2018-08-09 20:27, Bharat Kumar Gogada wrote:
> > > As per Figure 6-3 in PCIe r4.0, sec 6.2.6, ERR_ messages
> > > will be forwarded from the secondary interface to the primary interface,
> > > if the SERR# Enable bit in the Bridge Control register is set.
> > > Currently PCI_BRIDGE_CTL_SERR is being enabled only in
> > > ACPI flow.
> > > This patch enables PCI_BRIDGE_CTL_SERR for Type-1 PCI device.
> > >
> > > Signed-off-by: Bharat Kumar Gogada <bharat.kumar.gogada@xxxxxxxxxx>
> > > ---
> > >  drivers/pci/pcie/aer.c |   23 +++++++++++++++++++++++
> > >  1 files changed, 23 insertions(+), 0 deletions(-)
> > >
> > > diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> > > index a2e8838..4fb0d24 100644
> > > --- a/drivers/pci/pcie/aer.c
> > > +++ b/drivers/pci/pcie/aer.c
> > > @@ -343,6 +343,20 @@ int pci_enable_pcie_error_reporting(struct pci_dev
> > > *dev)
> > >  	if (!dev->aer_cap)
> > >  		return -EIO;
> > >
> > > +	if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
> > > +		u16 control;
> > > +
> > > +		/*
> > > +		 * A Type-1 PCI bridge will not forward ERR_ messages coming
> > > +		 * from an endpoint if SERR# forwarding is not enabled.
> > > +		 */
> > > +		pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &control);
> > > +		if (!(control & PCI_BRIDGE_CTL_SERR)) {
> > > +			control |= PCI_BRIDGE_CTL_SERR;
> > > +			pci_write_config_word(dev, PCI_BRIDGE_CONTROL, control);
> > > +		}
> > > +	}
> > > +
> > >  	return pcie_capability_set_word(dev, PCI_EXP_DEVCTL,
> > > PCI_EXP_AER_FLAGS);
> > >  }
> > >  EXPORT_SYMBOL_GPL(pci_enable_pcie_error_reporting);
> > > @@ -352,6 +366,15 @@ int pci_disable_pcie_error_reporting(struct pci_dev
> > > *dev)
> > >  	if (pcie_aer_get_firmware_first(dev))
> > >  		return -EIO;
> > >
> > > +	if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
> > > +		u16 control;
> > > +
> > > +		/* Clear SERR Forwarding */
> > > +		pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &control);
> > > +		control &= ~PCI_BRIDGE_CTL_SERR;
> > > +		pci_write_config_word(dev, PCI_BRIDGE_CONTROL, control);
> > > +	}
> > > +
> > >  	return pcie_capability_clear_word(dev, PCI_EXP_DEVCTL,
> > >  					  PCI_EXP_AER_FLAGS);
> > >  }
> >
> >
> > Hi Bjorn,
> >
> > I made some comments on patchv1., same I am putting it across here.
> >
> > what about hot-plug case ?
> > should not aer_init() call pci_enable_pcie_error_reporting() for all
> > the downstream pci_dev ?
> > and remove all the calls from drivers..
> > aer_init will be called for each device (pci_dev) while pciehp does
> > re-enumeration.
> > so probable we might want to call pci_enable_pcie_error_reporting()
> > but that dictates the design where AER framework is taking decision to
> > enable error reporting on behalf of drivers as well.
> > but thats fine I think, if drivers do not want to participate then 
> > they have
> > to call  pci_disable_pcie_error_reporting explicitly.
> > does this make sense ?
>
> I just replied to the original patch; sorry, I forgot to add you to
> the cc list.  Bharat, when people respond to your v<N> patch, can you
> please add them (and anybody else *they* added) to the cc list when
> you post your v<N+1> patch?
>
> If we set PCI_BRIDGE_CTL_SERR in the pci_configure_device() path,
> would that address your comments?

yes, that should do.

> There's still a separate question of where and how we should configure
> the error bits in PCI_EXP_DEVCTL (currently done in
> pci_enable_pcie_error_reporting()).
>
> Bjorn