Current Linux PCI core does not do any kind of power management to PCIe ports. This means that we waste energy and consume laptop battery even if the port has nothing connected to. These patches aim to change that to the right direction. Previous versions of the patches can be found below: v1: http://www.spinics.net/lists/linux-pci/msg49313.html v2: http://www.spinics.net/lists/linux-pci/msg50167.html v3: http://www.spinics.net/lists/linux-pci/msg50345.html v4: http://www.spinics.net/lists/linux-pci/msg50665.html This assumes that recent (starting from 2015) PCIe ports are capable of transition to D3hot/D3cold. We add a new flag to struct pci_dev 'bridge_d3' that is set whenever the PCI core thinks the port can be put to D3. The check in pci_pm_suspend_noirq() is then extended to cover devices where 'bridge_d3' is set. We then add two new functions pci_bridge_d3_device_changed/removed(). These are used to set and clear 'bridge_d3' whenever there is a change in device power management policy (or if the device is removed). For example when userspace forbids the device to enter D3cold pci_bridge_d3_device_changed() will clear 'bridge_d3' of the upstream bridge. For all PCI ports where 'bridge_d3' is set we also enable and unblock runtime PM automatically. Only exception is when the PCIe port claims to support hotplug. More information about that is in the changelog of patch [4/4]. Since this also touches xhci, I'm adding Mathias and Greg to check if the change looks reasonable. Changes to v4: - Use "Put PCIe ports into D3" instead of "move" in subject and comments. - Add new helper function pci_power_manageable() and use it to check if the port can be suspended instead of open-coding it everytime. - Changed pci_dev_check_d3cold() to follow what Rafael suggested. - Dropped call to pm_runtime_mark_last_busy() in pcie_port_runtime_resume() as PM core does that automatically when the function returns 0. - Added ACKs from Rafael. Changes to v3: - Make 'no_d3cold' persist for pci_dev. Once this is set through pci_d3cold_enable/disable(), it will persist unless changed again using the same functions. Those also handle setting and clearing 'bridge_d3' as necessary. - Add kernel command line parameter "pcie_port_pm=off|force" that can be used to forcibly disable/enable the feature. - Use runtime PM autosuspend instead of scheduling runtime suspend manually - Allow runtime PM always except when we are dealing with a hotplug bridge. Actual checking whether the port can be suspended is done in ->idle() and ->runtime_suspend() hooks based on 'bridge_d3'. Changes to v2: - Renamed and split pci_enable_d3cold() into two functions pci_d3cold_enable()/disable(). - Renamed pci_bridge_pm_update() into two functions pci_bridge_d3_device_changed() and pci_bridge_d3_device_removed() that should match better what they are doing. - Propagate ->bridge_d3 change to upstream bridges in pci_bridge_d3_update(). - Removed pci_can_suspend() in favor of doing ->bridge_d3 check directly in pci_pm_suspend_noirq(). - Extend runtime PM enabling for ports that are using native PCIe hotplug. - Call pm_runtime_no_callbacks() for PCIe port service devices (the are handled by the parent device). Changes to v1: - Dropped patch [2/6] as there is no need to use that function from other files anymore. - Dropped patches [5-6/6] in favor of using cut-off date. - Updated changelog of [1/4] to mention where in the PCI core PCI bridge and PCIe ports are skipped from being power managed. - Instead of checking at suspend time if it is possible to transition the port to D3, do it whenever power management status of a device (below a port) is changed or when it is added or removed to the bus. - Added patch [3/4] to runtime resume a bridge when ACPI hotplug event is received. Mika Westerberg (4): PCI: No need to set d3cold_allowed to PCIe ports PCI: Put PCIe ports into D3 during suspend ACPI / hotplug / PCI: Runtime resume bridge before rescan PCI: Add runtime PM support for PCIe ports Documentation/kernel-parameters.txt | 4 + drivers/pci/bus.c | 1 + drivers/pci/hotplug/acpiphp_glue.c | 8 +- drivers/pci/pci-driver.c | 5 +- drivers/pci/pci-sysfs.c | 5 ++ drivers/pci/pci.c | 175 ++++++++++++++++++++++++++++++++++++ drivers/pci/pci.h | 11 +++ drivers/pci/pcie/portdrv_core.c | 2 + drivers/pci/pcie/portdrv_pci.c | 51 ++++++++++- drivers/pci/remove.c | 2 + drivers/usb/host/xhci-pci.c | 2 +- include/linux/pci.h | 3 + 12 files changed, 259 insertions(+), 10 deletions(-) -- 2.8.0.rc3 -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
