On 3/1/24 3:06 PM, Bjorn Helgaas wrote: > On Sun, Feb 25, 2024 at 12:05:12PM -0800, Kuppuswamy Sathyanarayanan wrote: >> On 2/22/24 2:15 PM, Bjorn Helgaas wrote: >>> From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> >>> >>> Previous Kconfig allowed the possibility of enabling CONFIG_PCIE_DPC >>> without CONFIG_PCIE_EDR. The PCI Firmware Spec, r3.3, sec 4.5.1, >>> table 4-5, says an ACPI OS that requests control of DPC must also >>> advertise support for EDR. >>> >>> Remove CONFIG_PCIE_EDR and enable the EDR code with CONFIG_PCIE_DPC so that >>> enabling DPC also enables EDR for ACPI systems. Since EDR is an ACPI >>> feature, build edr.o only when CONFIG_ACPI is enabled. Stubs cover the >>> case when DPC is enabled without ACPI. >>> >>> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> >>> --- >>> drivers/acpi/pci_root.c | 2 +- >>> drivers/pci/pcie/Kconfig | 14 ++++---------- >>> drivers/pci/pcie/Makefile | 5 ++++- >>> drivers/pci/pcie/dpc.c | 10 ---------- >>> include/linux/pci-acpi.h | 4 ++-- >>> 5 files changed, 11 insertions(+), 24 deletions(-) >>> >>> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c >>> index efc292b6214e..bcaf3d3a5e05 100644 >>> --- a/drivers/acpi/pci_root.c >>> +++ b/drivers/acpi/pci_root.c >>> @@ -448,7 +448,7 @@ static u32 calculate_support(void) >>> support |= OSC_PCI_ASPM_SUPPORT | OSC_PCI_CLOCK_PM_SUPPORT; >>> if (pci_msi_enabled()) >>> support |= OSC_PCI_MSI_SUPPORT; >>> - if (IS_ENABLED(CONFIG_PCIE_EDR)) >>> + if (IS_ENABLED(CONFIG_PCIE_DPC)) /* DPC => EDR support */ >>> support |= OSC_PCI_EDR_SUPPORT; >> Since EDR internally touches AER registers, I still think we should >> make sure OS enables AER support before advertising the EDR support. > I guess you're suggesting that we should make it look like this? > > if (host_bridge->native_aer && IS_ENABLED(CONFIG_PCIE_DPC)) > > That doesn't seem right to me because the implementation note in PCI > Firmware r3.3, sec 4.6.12, shows the EDR flow when firmware maintains > control of AER and DPC, i.e., "host_bridge->native_aer" would be > false. No, my idea is to check for something like below: if (IS_ENABLED(CONFIG_PCIEAER) && IS_ENABLED(CONFIG_PCIE_DPC)) or if (pci_aer_available() && IS_ENABLED(CONFIG_PCIE_DPC) to ensure AER is not disabled by noaer command line option. Since EDR handler depends on AER routines (like pci_aer_raw_clear_status()) to |clear AER registers, we need to ensure AER is enabled in kernel before advertising suppor for EDR. > >>> return support; >>> diff --git a/drivers/pci/pcie/Kconfig b/drivers/pci/pcie/Kconfig >>> index 8999fcebde6a..21e98289fbe9 100644 >>> --- a/drivers/pci/pcie/Kconfig >>> +++ b/drivers/pci/pcie/Kconfig >>> @@ -137,6 +137,10 @@ config PCIE_DPC >>> have this capability or you do not want to use this feature, >>> it is safe to answer N. >>> >>> + On ACPI systems, this includes Error Disconnect Recover support, >>> + the hybrid model that uses both firmware and OS to implement DPC, >>> + as specified in the PCI Firmware Specification r3.3. >> Nit: Include some section reference? > I basically copied this from the PCIE_EDR help and updated the > revision number. But I don't think the firmware spec is a very good > reference because EDR is defined by ACPI. There's very little text in > the ACPI spec about EDR, but the firmware spec does assume you know > what *is* there. And the ACPI spec is available to anybody, unlike > the PCI firmware spec. > > + On ACPI systems, this includes Error Disconnect Recover support, > + the hybrid model that uses both firmware and OS to implement DPC, > + as specified in ACPI r6.5, sec 5.6.6. > >>> config PCIE_PTM >>> bool "PCI Express Precision Time Measurement support" >>> help >>> @@ -145,13 +149,3 @@ config PCIE_PTM >>> >>> This is only useful if you have devices that support PTM, but it >>> is safe to enable even if you don't. >>> - >>> -config PCIE_EDR >>> - bool "PCI Express Error Disconnect Recover support" >>> - depends on PCIE_DPC && ACPI >>> - help >>> - This option adds Error Disconnect Recover support as specified >>> - in the Downstream Port Containment Related Enhancements ECN to >>> - the PCI Firmware Specification r3.2. Enable this if you want to >>> - support hybrid DPC model which uses both firmware and OS to >>> - implement DPC. -- Sathyanarayanan Kuppuswamy Linux Kernel Developer
