Messages in this thread |  | | Subject | Re: [PATCH 1/5] PCI/DPC: Ignore devices with no AER Capability | From | "Kuppuswamy, Sathyanarayanan" <> | Date | Sat, 28 Nov 2020 13:56:23 -0800 |
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On 11/28/20 1:53 PM, Bjorn Helgaas wrote: > On Sat, Nov 28, 2020 at 01:49:46PM -0800, Kuppuswamy, Sathyanarayanan wrote: >> On 11/28/20 12:24 PM, Bjorn Helgaas wrote: >>> 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@google.com> >>>>> >>>>> 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@google.com> >>>>> Cc: Olof Johansson <olof@lixom.net> >>>>> --- >>>>> 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. >> Got it. But further looking into it, I am wondering whether >> we should keep this dependency? Currently we just use it to >> dump the error information. Do we need to create dependency >> between DPC and AER (which is functionality not dependent) just >> to see more details about the error? > > That's a good question, but I don't really want to get into the actual > operation of the AER and DPC drivers in this series, so maybe > something we should explore later. In that case, can you move this check to drivers/pci/pcie/portdrv_core.c? I don't see the point of distributed checks in both get_port_device_capability() and dpc_probe(). >
-- Sathyanarayanan Kuppuswamy Linux Kernel Developer
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