Commit a78cf965 authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt Committed by Bjorn Helgaas
Browse files

PCI/ACPI: Evaluate PCI Boot Configuration _DSM 

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: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
[bhelgaas: commit log]
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent a188339c

drivers/acpi/pci_root.c

+12 −0
Original line number Diff line number Diff line
@@ -894,6 +894,7 @@ 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;
@@ -930,6 +931,17 @@ 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;



	/*

	 * 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);

include/linux/pci-acpi.h

+4 −3
Original line number Diff line number Diff line
@@ -107,6 +107,7 @@ static inline void acpiphp_check_host_bridge(struct acpi_device *adev) { } 
#endif



extern const guid_t pci_acpi_dsm_guid;

#define IGNORE_PCI_BOOT_CONFIG_DSM	0x05

#define DEVICE_LABEL_DSM		0x07

#define RESET_DELAY_DSM			0x08

#define FUNCTION_DELAY_DSM		0x09

include/linux/pci.h

+2 −0
Original line number Diff line number Diff line
@@ -505,6 +505,8 @@ 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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