PCI/ACPI: Optimize device state transition delays (e33caa82) · Commits · 戴 / test

drivers/pci/pci-acpi.c

+74 −0

Original line number	Diff line number	Diff line
		@@ -537,11 +537,32 @@ static struct pci_platform_pm_ops acpi_pci_platform_pm = {

		void acpi_pci_add_bus(struct pci_bus *bus)
		{
		union acpi_object *obj;
		struct pci_host_bridge *bridge;

		if (acpi_pci_disabled \|\| !bus->bridge)
		return;

		acpi_pci_slot_enumerate(bus);
		acpiphp_enumerate_slots(bus);

		/*
		* For a host bridge, check its _DSM for function 8 and if
		* that is available, mark it in pci_host_bridge.
		*/
		if (!pci_is_root_bus(bus))
		return;

		obj = acpi_evaluate_dsm(ACPI_HANDLE(bus->bridge), pci_acpi_dsm_uuid, 3,
		RESET_DELAY_DSM, NULL);
		if (!obj)
		return;

		if (obj->type == ACPI_TYPE_INTEGER && obj->integer.value == 1) {
		bridge = pci_find_host_bridge(bus);
		bridge->ignore_reset_delay = 1;
		}
		ACPI_FREE(obj);
		}

		void acpi_pci_remove_bus(struct pci_bus *bus)
		@@ -567,6 +588,57 @@ static struct acpi_device acpi_pci_find_companion(struct device dev)
		check_children);
		}

		/**
		* pci_acpi_optimize_delay - optimize PCI D3 and D3cold delay from ACPI
		* @pdev: the PCI device whose delay is to be updated
		* @adev: the companion ACPI device of this PCI device
		*
		* Update the d3_delay and d3cold_delay of a PCI device from the ACPI _DSM
		* control method of either the device itself or the PCI host bridge.
		*
		* Function 8, "Reset Delay," applies to the entire hierarchy below a PCI
		* host bridge. If it returns one, the OS may assume that all devices in
		* the hierarchy have already completed power-on reset delays.
		*
		* Function 9, "Device Readiness Durations," applies only to the object
		* where it is located. It returns delay durations required after various
		* events if the device requires less time than the spec requires. Delays
		* from this function take precedence over the Reset Delay function.
		*
		* These _DSM functions are defined by the draft ECN of January 28, 2014,
		* titled "ACPI additions for FW latency optimizations."
		*/
		static void pci_acpi_optimize_delay(struct pci_dev *pdev,
		acpi_handle handle)
		{
		struct pci_host_bridge *bridge = pci_find_host_bridge(pdev->bus);
		int value;
		union acpi_object obj, elements;

		if (bridge->ignore_reset_delay)
		pdev->d3cold_delay = 0;

		obj = acpi_evaluate_dsm(handle, pci_acpi_dsm_uuid, 3,
		FUNCTION_DELAY_DSM, NULL);
		if (!obj)
		return;

		if (obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 5) {
		elements = obj->package.elements;
		if (elements[0].type == ACPI_TYPE_INTEGER) {
		value = (int)elements[0].integer.value / 1000;
		if (value < PCI_PM_D3COLD_WAIT)
		pdev->d3cold_delay = value;
		}
		if (elements[3].type == ACPI_TYPE_INTEGER) {
		value = (int)elements[3].integer.value / 1000;
		if (value < PCI_PM_D3_WAIT)
		pdev->d3_delay = value;
		}
		}
		ACPI_FREE(obj);
		}

		static void pci_acpi_setup(struct device *dev)
		{
		struct pci_dev *pci_dev = to_pci_dev(dev);
		@@ -575,6 +647,8 @@ static void pci_acpi_setup(struct device *dev)
		if (!adev)
		return;

		pci_acpi_optimize_delay(pci_dev, adev->handle);

		pci_acpi_add_pm_notifier(adev, pci_dev);
		if (!adev->wakeup.flags.valid)
		return;

include/linux/pci-acpi.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -79,6 +79,8 @@ static inline void acpiphp_check_host_bridge(struct acpi_device *adev) { }

		extern const u8 pci_acpi_dsm_uuid[];
		#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) { }

include/linux/pci.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -406,6 +406,7 @@ struct pci_host_bridge {
		struct list_head windows; /* resource_entry */
		void (release_fn)(struct pci_host_bridge );
		void *release_data;
		unsigned int ignore_reset_delay:1; /* for entire hierarchy */
		};

		#define to_pci_host_bridge(n) container_of(n, struct pci_host_bridge, dev)

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