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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Sat, 15 Jun 2019 10:23:57 +1000
Subject: [PATCH 1/4] PCI/ACPI: Evaluate PCI Boot Configuration _DSM
Origin: https://git.kernel.org/linus/a78cf9657ba5426f54aa93a067c10d097944c082
Evaluate _DSM Function #5, the "PCI Boot Configuration" function. If the
result is 0, the OS should preserve any resource assignments made by the
firmware.
Link: https://lore.kernel.org/r/20190615002359.29577-2-benh@kernel.crashing.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[bhelgaas: commit log]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
drivers/acpi/pci_root.c | 12 ++++++++++++
include/linux/pci-acpi.h | 7 ++++---
include/linux/pci.h | 2 ++
3 files changed, 18 insertions(+), 3 deletions(-)
Index: linux/drivers/acpi/pci_root.c
===================================================================
--- linux.orig/drivers/acpi/pci_root.c
+++ linux/drivers/acpi/pci_root.c
@@ -884,6 +884,7 @@ struct pci_bus *acpi_pci_root_create(str
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;
@@ -920,6 +921,17 @@ struct pci_bus *acpi_pci_root_create(str
if (!(root->osc_control_set & OSC_PCI_EXPRESS_LTR_CONTROL))
host_bridge->native_ltr = 0;
+ /*
+ * Evaluate the "PCI Boot Configuration" _DSM Function. If it
+ * exists and returns 0, we must preserve any PCI resource
+ * assignments made by firmware for this host bridge.
+ */
+ 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);
Index: linux/include/linux/pci-acpi.h
===================================================================
--- linux.orig/include/linux/pci-acpi.h
+++ linux/include/linux/pci-acpi.h
@@ -107,9 +107,10 @@ static inline void acpiphp_check_host_br
#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) { }
Index: linux/include/linux/pci.h
===================================================================
--- linux.orig/include/linux/pci.h
+++ linux/include/linux/pci.h
@@ -486,6 +486,8 @@ 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 resource setup */
+
/* Resource alignment requirements */
resource_size_t (*align_resource)(struct pci_dev *dev,
const struct resource *res,
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