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. > > 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.
