On 1/8/2024 11:46 AM, Matthew W Carlis wrote: > Hello again, sorry for the delayed response.. I have been on PTO. The above patch > doesn't fix the problem in our systems as host->native_dpc is not set due to > not using or having support for Error Disconnect Recovery (EDR). I wonder if The only condition we check before requesting DPC control is whether OS supports both EDR and DPC. As long as you have enabled related configs (IS_ENABLED(CONFIG_PCIE_DPC) && IS_ENABLED(CONFIG_PCIE_EDR)), this will be true. Enabling these configs does not mean you are using it. Any reason why you don't enable it in your case? > host->native_dpc is a misleading name a way... Misleading in the sense that > setting host->native_aer implies firmware intends the OS to control AER, whereas > host->native_dpc being set appears to have an additional requirement on the > use/support of EDR in addition to DPC. When I was working on the patch as > submitted I had been thinking about all of these fields & my thinking was > as follows.. The kernel requires host->native_aer in order to control AER, but > it could control DPC whether host->native_dpc is set or unset. Therefore, if > the kernel will control AER it should also control DPC on any capable devices. > Of course there is also the requirement of having built with CONFIG_PCIE_AER > & CONFIG_PCIE_DPC. Please advise if my understanding of all this is incorrect.. > > Thanks, > -Matt > > I included an update to the patch submitted in chain which should remove the > build error that occured when CONFIG_PCIE_AER was not set. Including it > in case my understanding of EDR/DPC/etc is correct. > > diff --git a/drivers/pci/pcie/portdrv.c b/drivers/pci/pcie/portdrv.c > index 14a4b89a3b83..2fc006f12988 100644 > --- a/drivers/pci/pcie/portdrv.c > +++ b/drivers/pci/pcie/portdrv.c > @@ -257,12 +257,18 @@ static int get_port_device_capability(struct pci_dev *dev) > } > > /* > + * _OSC AER Control is required by the OS & requires OS to control AER, > + * but _OSC DPC Control isn't required by the OS to control DPC; however > + * it does require the OS to control DPC. _OSC DPC Control also requres > + * _OSC EDR Control (Error Disconnect Recovery) (PCI Firmware - DPC ECN rev3.2) > + * PCI_Express_Base 6.1, 6.2.11 Determination of DPC Control recommends > + * platform fw or OS always link control of DPC to AER. > + * > * With dpc-native, allow Linux to use DPC even if it doesn't have > * permission to use AER. > */ > if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC) && > - pci_aer_available() && > - (pcie_ports_dpc_native || (services & PCIE_PORT_SERVICE_AER))) > + pci_aer_available() && (pcie_ports_dpc_native || host->native_aer)) > services |= PCIE_PORT_SERVICE_DPC; > > if (pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM || > -- Sathyanarayanan Kuppuswamy Linux Kernel Developer
