| Message ID | 20190615002359.29577-2-benh@kernel.crashing.org (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
| Series | [1/4] arm64: pci: acpi: Use pci_assign_unassigned_root_bus_resources() | expand |
Match the subject line convention for this file, e.g., PCI/ACPI: Evaluate PCI Boot Configuration _DSM On Sat, Jun 15, 2019 at 10:23:57AM +1000, Benjamin Herrenschmidt wrote: > This reads _DSM #5 value on root bridges, and when 0, sets a "preserve_config" > flag in the host bridge structure indicating that the FW has requested that > the existing configuration be preserved. Wrap to 75 or so, so this doesn't overflow 80 columns when "git log" adds its indentation. > The upcoming spec change to define _DSM #5 for host bridges states that > this should be the default behaviour, however doing so would be very > intrusive and break existing setups. So we leave the default to be > the existing behaviour. This paragraph is incorrect. Just remove it completely. I would silently fix stuff like this if I applied these, but you can do it if you repost these. > Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> > --- > drivers/acpi/pci_root.c | 23 +++++++++++++++++++++++ > include/linux/pci-acpi.h | 7 ++++--- > include/linux/pci.h | 2 ++ > 3 files changed, 29 insertions(+), 3 deletions(-) > > diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c > index 39f5d172e84f..217b3916f0f1 100644 > --- a/drivers/acpi/pci_root.c > +++ b/drivers/acpi/pci_root.c > @@ -881,6 +881,7 @@ struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root, > int node = acpi_get_node(device->handle); > struct pci_bus *bus; > struct pci_host_bridge *host_bridge; > + union acpi_object *obj; > > info->root = root; > info->bridge = device; > @@ -917,6 +918,28 @@ struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root, > if (!(root->osc_control_set & OSC_PCI_EXPRESS_LTR_CONTROL)) > host_bridge->native_ltr = 0; > > + /* > + * Invoke the PCI device specific method (_DSM) #5 'Ignore PCI Boot > + * Configuration', on the host bridge. This tells us whether the > + * firmware wants us to preserve or reassign the configuration of > + * the PCI resource tree for this root bridge. > + * > + * For now, we only care about the function being present and returning > + * 0, which we use to set a flag indicating that we'll preserve the > + * FW configuration. > + * > + * This diverges from the spec which states that 0 is also the default > + * in absence of _DSM #5. We do that today to work around the fact that > + * our arm64 code doesn't implement the right defaults otherwise. This > + * will be superseeded by a more thorough handling of _DSM #5 once the > + * resource survey code has been consolidated further. > + */ > + obj = acpi_evaluate_dsm(ACPI_HANDLE(bus->bridge), &pci_acpi_dsm_guid, 1, > + IGNORE_PCI_BOOT_CONFIG_DSM, NULL); > + if (obj && obj->type == ACPI_TYPE_INTEGER && obj->integer.value == 0) > + host_bridge->preserve_config = 1; > + ACPI_FREE(obj); > + > pci_scan_child_bus(bus); > pci_set_host_bridge_release(host_bridge, acpi_pci_root_release_info, > info); > diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h > index 8082b612f561..62b7fdcc661c 100644 > --- a/include/linux/pci-acpi.h > +++ b/include/linux/pci-acpi.h > @@ -107,9 +107,10 @@ static inline void acpiphp_check_host_bridge(struct acpi_device *adev) { } > #endif > > extern const guid_t pci_acpi_dsm_guid; > -#define DEVICE_LABEL_DSM 0x07 > -#define RESET_DELAY_DSM 0x08 > -#define FUNCTION_DELAY_DSM 0x09 > +#define IGNORE_PCI_BOOT_CONFIG_DSM 0x05 > +#define DEVICE_LABEL_DSM 0x07 > +#define RESET_DELAY_DSM 0x08 > +#define FUNCTION_DELAY_DSM 0x09 > > #else /* CONFIG_ACPI */ > static inline void acpi_pci_add_bus(struct pci_bus *bus) { } > diff --git a/include/linux/pci.h b/include/linux/pci.h > index dd436da7eccc..c50389b8df3c 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -506,6 +506,8 @@ struct pci_host_bridge { > unsigned int native_shpc_hotplug:1; /* OS may use SHPC hotplug */ > unsigned int native_pme:1; /* OS may use PCIe PME */ > unsigned int native_ltr:1; /* OS may use PCIe LTR */ > + unsigned int preserve_config:1; /* Preserve FW resources setup */ > + > /* Resource alignment requirements */ > resource_size_t (*align_resource)(struct pci_dev *dev, > const struct resource *res, > -- > 2.17.1 >
diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c index 39f5d172e84f..217b3916f0f1 100644 --- a/drivers/acpi/pci_root.c +++ b/drivers/acpi/pci_root.c @@ -881,6 +881,7 @@ struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root, int node = acpi_get_node(device->handle); struct pci_bus *bus; struct pci_host_bridge *host_bridge; + union acpi_object *obj; info->root = root; info->bridge = device; @@ -917,6 +918,28 @@ struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root, if (!(root->osc_control_set & OSC_PCI_EXPRESS_LTR_CONTROL)) host_bridge->native_ltr = 0; + /* + * Invoke the PCI device specific method (_DSM) #5 'Ignore PCI Boot + * Configuration', on the host bridge. This tells us whether the + * firmware wants us to preserve or reassign the configuration of + * the PCI resource tree for this root bridge. + * + * For now, we only care about the function being present and returning + * 0, which we use to set a flag indicating that we'll preserve the + * FW configuration. + * + * This diverges from the spec which states that 0 is also the default + * in absence of _DSM #5. We do that today to work around the fact that + * our arm64 code doesn't implement the right defaults otherwise. This + * will be superseeded by a more thorough handling of _DSM #5 once the + * resource survey code has been consolidated further. + */ + obj = acpi_evaluate_dsm(ACPI_HANDLE(bus->bridge), &pci_acpi_dsm_guid, 1, + IGNORE_PCI_BOOT_CONFIG_DSM, NULL); + if (obj && obj->type == ACPI_TYPE_INTEGER && obj->integer.value == 0) + host_bridge->preserve_config = 1; + ACPI_FREE(obj); + pci_scan_child_bus(bus); pci_set_host_bridge_release(host_bridge, acpi_pci_root_release_info, info); diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h index 8082b612f561..62b7fdcc661c 100644 --- a/include/linux/pci-acpi.h +++ b/include/linux/pci-acpi.h @@ -107,9 +107,10 @@ static inline void acpiphp_check_host_bridge(struct acpi_device *adev) { } #endif extern const guid_t pci_acpi_dsm_guid; -#define DEVICE_LABEL_DSM 0x07 -#define RESET_DELAY_DSM 0x08 -#define FUNCTION_DELAY_DSM 0x09 +#define IGNORE_PCI_BOOT_CONFIG_DSM 0x05 +#define DEVICE_LABEL_DSM 0x07 +#define RESET_DELAY_DSM 0x08 +#define FUNCTION_DELAY_DSM 0x09 #else /* CONFIG_ACPI */ static inline void acpi_pci_add_bus(struct pci_bus *bus) { } diff --git a/include/linux/pci.h b/include/linux/pci.h index dd436da7eccc..c50389b8df3c 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -506,6 +506,8 @@ struct pci_host_bridge { unsigned int native_shpc_hotplug:1; /* OS may use SHPC hotplug */ unsigned int native_pme:1; /* OS may use PCIe PME */ unsigned int native_ltr:1; /* OS may use PCIe LTR */ + unsigned int preserve_config:1; /* Preserve FW resources setup */ + /* Resource alignment requirements */ resource_size_t (*align_resource)(struct pci_dev *dev, const struct resource *res,
This reads _DSM #5 value on root bridges, and when 0, sets a "preserve_config" flag in the host bridge structure indicating that the FW has requested that the existing configuration be preserved. The upcoming spec change to define _DSM #5 for host bridges states that this should be the default behaviour, however doing so would be very intrusive and break existing setups. So we leave the default to be the existing behaviour. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> --- drivers/acpi/pci_root.c | 23 +++++++++++++++++++++++ include/linux/pci-acpi.h | 7 ++++--- include/linux/pci.h | 2 ++ 3 files changed, 29 insertions(+), 3 deletions(-)