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9d26d3a8f1
Currently the Linux PCI core does not touch power state of PCI bridges and PCIe ports when system suspend is entered. Leaving them in D0 consumes power unnecessarily and may prevent the CPU from entering deeper C-states. With recent PCIe hardware we can power down the ports to save power given that we take into account few restrictions: - The PCIe port hardware is recent enough, starting from 2015. - Devices connected to PCIe ports are effectively in D3cold once the port is transitioned to D3 (the config space is not accessible anymore and the link may be powered down). - Devices behind the PCIe port need to be allowed to transition to D3cold and back. There is a way both drivers and userspace can forbid this. - If the device behind the PCIe port is capable of waking the system it needs to be able to do so from D3cold. This patch adds a new flag to struct pci_device called 'bridge_d3'. This flag is set and cleared by the PCI core whenever there is a change in power management state of any of the devices behind the PCIe port. When system later on is suspended we only need to check this flag and if it is true transition the port to D3 otherwise we leave it in D0. Also provide override mechanism via command line parameter "pcie_port_pm=[off|force]" that can be used to disable or enable the feature regardless of the BIOS manufacturing date. Tested-by: Lukas Wunner <lukas@wunner.de> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
168 lines
3.7 KiB
C
168 lines
3.7 KiB
C
#include <linux/pci.h>
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#include <linux/module.h>
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#include <linux/pci-aspm.h>
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#include "pci.h"
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static void pci_free_resources(struct pci_dev *dev)
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{
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int i;
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for (i = 0; i < PCI_NUM_RESOURCES; i++) {
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struct resource *res = dev->resource + i;
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if (res->parent)
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release_resource(res);
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}
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}
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static void pci_stop_dev(struct pci_dev *dev)
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{
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pci_pme_active(dev, false);
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if (dev->is_added) {
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pci_proc_detach_device(dev);
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pci_remove_sysfs_dev_files(dev);
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device_release_driver(&dev->dev);
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dev->is_added = 0;
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}
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if (dev->bus->self)
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pcie_aspm_exit_link_state(dev);
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}
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static void pci_destroy_dev(struct pci_dev *dev)
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{
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if (!dev->dev.kobj.parent)
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return;
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device_del(&dev->dev);
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down_write(&pci_bus_sem);
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list_del(&dev->bus_list);
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up_write(&pci_bus_sem);
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pci_free_resources(dev);
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put_device(&dev->dev);
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}
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void pci_remove_bus(struct pci_bus *bus)
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{
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pci_proc_detach_bus(bus);
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down_write(&pci_bus_sem);
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list_del(&bus->node);
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pci_bus_release_busn_res(bus);
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up_write(&pci_bus_sem);
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pci_remove_legacy_files(bus);
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if (bus->ops->remove_bus)
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bus->ops->remove_bus(bus);
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pcibios_remove_bus(bus);
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device_unregister(&bus->dev);
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}
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EXPORT_SYMBOL(pci_remove_bus);
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static void pci_stop_bus_device(struct pci_dev *dev)
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{
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struct pci_bus *bus = dev->subordinate;
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struct pci_dev *child, *tmp;
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/*
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* Stopping an SR-IOV PF device removes all the associated VFs,
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* which will update the bus->devices list and confuse the
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* iterator. Therefore, iterate in reverse so we remove the VFs
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* first, then the PF.
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*/
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if (bus) {
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list_for_each_entry_safe_reverse(child, tmp,
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&bus->devices, bus_list)
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pci_stop_bus_device(child);
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}
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pci_stop_dev(dev);
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}
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static void pci_remove_bus_device(struct pci_dev *dev)
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{
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struct pci_bus *bus = dev->subordinate;
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struct pci_dev *child, *tmp;
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if (bus) {
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list_for_each_entry_safe(child, tmp,
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&bus->devices, bus_list)
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pci_remove_bus_device(child);
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pci_remove_bus(bus);
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dev->subordinate = NULL;
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}
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pci_bridge_d3_device_removed(dev);
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pci_destroy_dev(dev);
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}
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/**
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* pci_stop_and_remove_bus_device - remove a PCI device and any children
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* @dev: the device to remove
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*
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* Remove a PCI device from the device lists, informing the drivers
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* that the device has been removed. We also remove any subordinate
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* buses and children in a depth-first manner.
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*
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* For each device we remove, delete the device structure from the
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* device lists, remove the /proc entry, and notify userspace
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* (/sbin/hotplug).
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*/
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void pci_stop_and_remove_bus_device(struct pci_dev *dev)
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{
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pci_stop_bus_device(dev);
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pci_remove_bus_device(dev);
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}
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EXPORT_SYMBOL(pci_stop_and_remove_bus_device);
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void pci_stop_and_remove_bus_device_locked(struct pci_dev *dev)
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{
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pci_lock_rescan_remove();
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pci_stop_and_remove_bus_device(dev);
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pci_unlock_rescan_remove();
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}
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EXPORT_SYMBOL_GPL(pci_stop_and_remove_bus_device_locked);
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void pci_stop_root_bus(struct pci_bus *bus)
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{
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struct pci_dev *child, *tmp;
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struct pci_host_bridge *host_bridge;
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if (!pci_is_root_bus(bus))
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return;
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host_bridge = to_pci_host_bridge(bus->bridge);
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list_for_each_entry_safe_reverse(child, tmp,
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&bus->devices, bus_list)
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pci_stop_bus_device(child);
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/* stop the host bridge */
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device_release_driver(&host_bridge->dev);
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}
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EXPORT_SYMBOL_GPL(pci_stop_root_bus);
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void pci_remove_root_bus(struct pci_bus *bus)
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{
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struct pci_dev *child, *tmp;
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struct pci_host_bridge *host_bridge;
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if (!pci_is_root_bus(bus))
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return;
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host_bridge = to_pci_host_bridge(bus->bridge);
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list_for_each_entry_safe(child, tmp,
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&bus->devices, bus_list)
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pci_remove_bus_device(child);
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pci_remove_bus(bus);
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host_bridge->bus = NULL;
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/* remove the host bridge */
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device_unregister(&host_bridge->dev);
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}
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EXPORT_SYMBOL_GPL(pci_remove_root_bus);
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