Messages in this thread Patch in this message | | | Subject | Re: [PATCH v2 2/2] PCI/DPC: Allow Native DPC Host Bridges to use DPC | From | "Kuppuswamy, Sathyanarayanan" <> | Date | Sat, 25 Apr 2020 13:46:45 -0700 |
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On 4/23/20 8:11 AM, Derrick, Jonathan wrote: > Hi Sathyanarayanan, > > On Wed, 2020-04-22 at 15:50 -0700, Kuppuswamy, Sathyanarayanan wrote: >> >> On 4/20/20 2:37 PM, Jon Derrick wrote: >>> The existing portdrv model prevents DPC services without either OS >>> control (_OSC) granted to AER services, a Host Bridge requesting Native >>> AER, or using one of the 'pcie_ports=' parameters of 'native' or >>> 'dpc-native'. >>> >>> The DPC port service driver itself will also fail to probe if the kernel >>> assumes the port is using Firmware-First AER. It's a reasonable >>> expectation that a port using Firmware-First AER will also be using >>> Firmware-First DPC, however if a Host Bridge requests Native DPC, the >>> DPC driver should allow it and not fail to bind due to AER capability >>> settings. >>> >>> Host Bridges which request Native DPC port services will also likely >>> request Native AER, however it shouldn't be a requirement. This patch >>> allows ports on those Host Bridges to have DPC port services. >>> >>> This will avoid the unlikely situation where the port is Firmware-First >>> AER and Native DPC, and a BIOS or switch firmware preconfiguration of >>> the DPC trigger could result in unhandled DPC events. >>> >>> Signed-off-by: Jon Derrick <jonathan.derrick@intel.com> >>> --- >>> drivers/pci/pcie/dpc.c | 3 ++- >>> drivers/pci/pcie/portdrv_core.c | 3 ++- >>> 2 files changed, 4 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c >>> index 7621704..3f3106f 100644 >>> --- a/drivers/pci/pcie/dpc.c >>> +++ b/drivers/pci/pcie/dpc.c >>> @@ -284,7 +284,8 @@ static int dpc_probe(struct pcie_device *dev) >>> int status; >>> u16 ctl, cap; >>> >>> - if (pcie_aer_get_firmware_first(pdev) && !pcie_ports_dpc_native) >>> + if (pcie_aer_get_firmware_first(pdev) && !pcie_ports_dpc_native && >>> + !pci_find_host_bridge(pdev->bus)->native_dpc) >> Why do it in probe as well ? if host->native_dpc is not set then the >> device DPC probe it self won't happen right ? > > Portdrv only enables the interrupt and allows the probe to occur.
Please check the following snippet of code (from portdrv_core.c).
IIUC, pcie_device_init() will not be called if PCIE_PORT_SERVICE_DPC is not set in capabilities. Your change in portdrv_core.c already selectively enables the PCIE_PORT_SERVICE_DPC service based on native_dpc value.
So IMO, adding native_dpc check in dpc_probe() is redundant.
int pcie_port_device_register(struct pci_dev *dev) /* Allocate child services if any */ status = -ENODEV; nr_service = 0; for (i = 0; i < PCIE_PORT_DEVICE_MAXSERVICES; i++) { int service = 1 << i; if (!(capabilities & service)) continue; if (!pcie_device_init(dev, service, irqs[i])) nr_service++; }
> > The probe itself will still fail if there's a mixed-mode _OSC > negotiated AER & DPC, due to pcie_aer_get_firmware_first returning 1 > for AER and no check for DPC. > > I don't know if such a platform will exist, but the kernel is already > wired for 'dpc-native' so it makes sense to extend it for this.. > > This transform might be more readable: > if (pcie_aer_get_firmware_first(pdev) && > !(pcie_ports_dpc_native || hb->native_dpc)) > > > >>> return -ENOTSUPP; >>> >>> status = devm_request_threaded_irq(device, dev->irq, dpc_irq, >>> diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c >>> index 50a9522..f2139a1 100644 >>> --- a/drivers/pci/pcie/portdrv_core.c >>> +++ b/drivers/pci/pcie/portdrv_core.c >>> @@ -256,7 +256,8 @@ static int get_port_device_capability(struct pci_dev *dev) >>> */ >>> if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC) && >>> pci_aer_available() && >>> - (pcie_ports_dpc_native || (services & PCIE_PORT_SERVICE_AER))) >>> + (pcie_ports_dpc_native || host->native_dpc || >>> + (services & PCIE_PORT_SERVICE_AER))) >>> services |= PCIE_PORT_SERVICE_DPC; >>> >>> if (pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM || >>>
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