On Wed, Nov 25, 2020 at 06:01:57PM -0800, Kuppuswamy, Sathyanarayanan wrote:
> On 11/25/20 5:18 PM, Bjorn Helgaas wrote:
> > From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> >
> > Downstream Ports may support DPC regardless of whether they support AER
> > (see PCIe r5.0, sec 6.2.10.2). Previously, if the user booted with
> > "pcie_ports=dpc-native", it was possible for dpc_probe() to succeed even if
> > the device had no AER Capability, but dpc_get_aer_uncorrect_severity()
> > depends on the AER Capability.
> >
> > dpc_probe() previously failed if:
> >
> > !pcie_aer_is_native(pdev) && !pcie_ports_dpc_native
> > !(pcie_aer_is_native() || pcie_ports_dpc_native) # by De Morgan's law
> >
> > so it succeeded if:
> >
> > pcie_aer_is_native() || pcie_ports_dpc_native
> >
> > Fail dpc_probe() if the device has no AER Capability.
> >
> > Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> > Cc: Olof Johansson <olof@xxxxxxxxx>
> > ---
> > drivers/pci/pcie/dpc.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
> > index e05aba86a317..ed0dbc43d018 100644
> > --- a/drivers/pci/pcie/dpc.c
> > +++ b/drivers/pci/pcie/dpc.c
> > @@ -287,6 +287,9 @@ static int dpc_probe(struct pcie_device *dev)
> > int status;
> > u16 ctl, cap;
> > + if (!pdev->aer_cap)
> > + return -ENOTSUPP;
> Don't we check aer_cap support in drivers/pci/pcie/portdrv_core.c ?
>
> We don't enable DPC service, if AER service is not enabled. And AER
> service is only enabled if AER capability is supported.
>
> So dpc_probe() should not happen if AER capability is not supported?
I don't think that's always true. If I'm reading this right, we have
this:
get_port_device_capability(...)
{
#ifdef CONFIG_PCIEAER
if (dev->aer_cap && ...)
services |= PCIE_PORT_SERVICE_AER;
#endif
if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC) &&
pci_aer_available() &&
(pcie_ports_dpc_native || (services & PCIE_PORT_SERVICE_AER)))
services |= PCIE_PORT_SERVICE_DPC;
}
and in the case where:
- CONFIG_PCIEAER=y
- booted with "pcie_ports=dpc-native" (pcie_ports_dpc_native is true)
- "dev" has no AER capability
- "dev" has DPC capability
I think we do enable PCIE_PORT_SERVICE_DPC.
> 206 static int get_port_device_capability(struct pci_dev *dev)
> ...
> ...
> 251 if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC) &&
> 252 host->native_dpc &&
> 253 (host->native_dpc || (services & PCIE_PORT_SERVICE_AER)))
> 254 services |= PCIE_PORT_SERVICE_DPC;
> 255
>
> > +
> > if (!pcie_aer_is_native(pdev) && !pcie_ports_dpc_native)
> > return -ENOTSUPP;
> >
>
> --
> Sathyanarayanan Kuppuswamy
> Linux Kernel Developer
