From 9d26d3a8f1b0c442339a235f9508bdad8af91043 Mon Sep 17 00:00:00 2001 From: Mika Westerberg Date: Thu, 2 Jun 2016 11:17:12 +0300 Subject: PCI: Put PCIe ports into D3 during suspend 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 Signed-off-by: Mika Westerberg Signed-off-by: Bjorn Helgaas Acked-by: Rafael J. Wysocki --- Documentation/kernel-parameters.txt | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'Documentation') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 82b42c958d1c..86edee4cedd4 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -3047,6 +3047,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted. compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe ports driver. + pcie_port_pm= [PCIE] PCIe port power management handling: + off Disable power management of all PCIe ports + force Forcibly enable power management of all PCIe ports + pcie_pme= [PCIE,PM] Native PCIe PME signaling options: nomsi Do not use MSI for native PCIe PME signaling (this makes all PCIe root ports use INTx for all services). -- cgit v1.2.3 From e16b46605960bd071a3e26f316e0bb600ae91e37 Mon Sep 17 00:00:00 2001 From: Keith Busch Date: Thu, 21 Jul 2016 21:40:28 -0600 Subject: PCI: Allow additional bus numbers for hotplug bridges A user may hot add a switch requiring more than one bus to enumerate. This previously required a system reboot if BIOS did not sufficiently pad the bus resource, which they frequently don't do. Add a kernel parameter so a user can specify the minimum number of bus numbers to reserve for a hotplug bridge's subordinate buses so rebooting won't be necessary. The default is 1, which is equivalent to previous behavior. Signed-off-by: Keith Busch Signed-off-by: Bjorn Helgaas --- Documentation/kernel-parameters.txt | 3 +++ drivers/pci/pci.c | 8 ++++++++ drivers/pci/probe.c | 9 +++++++++ include/linux/pci.h | 1 + 4 files changed, 21 insertions(+) (limited to 'Documentation') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 82b42c958d1c..487e799b1da2 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -3016,6 +3016,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted. hpmemsize=nn[KMG] The fixed amount of bus space which is reserved for hotplug bridge's memory window. Default size is 2 megabytes. + hpbussize=nn The minimum amount of additional bus numbers + reserved for buses below a hotplug bridge. + Default is 1. realloc= Enable/disable reallocating PCI bridge resources if allocations done by BIOS are too small to accommodate resources required by all child diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index c8b4dbdd1bdd..f18ea90cf91a 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -81,6 +81,9 @@ unsigned long pci_cardbus_mem_size = DEFAULT_CARDBUS_MEM_SIZE; unsigned long pci_hotplug_io_size = DEFAULT_HOTPLUG_IO_SIZE; unsigned long pci_hotplug_mem_size = DEFAULT_HOTPLUG_MEM_SIZE; +#define DEFAULT_HOTPLUG_BUS_SIZE 1 +unsigned long pci_hotplug_bus_size = DEFAULT_HOTPLUG_BUS_SIZE; + enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_DEFAULT; /* @@ -5021,6 +5024,11 @@ static int __init pci_setup(char *str) pci_hotplug_io_size = memparse(str + 9, &str); } else if (!strncmp(str, "hpmemsize=", 10)) { pci_hotplug_mem_size = memparse(str + 10, &str); + } else if (!strncmp(str, "hpbussize=", 10)) { + pci_hotplug_bus_size = + simple_strtoul(str + 10, &str, 0); + if (pci_hotplug_bus_size > 0xff) + pci_hotplug_bus_size = DEFAULT_HOTPLUG_BUS_SIZE; } else if (!strncmp(str, "pcie_bus_tune_off", 17)) { pcie_bus_config = PCIE_BUS_TUNE_OFF; } else if (!strncmp(str, "pcie_bus_safe", 13)) { diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 8e3ef720997d..f680099c110d 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2076,6 +2076,15 @@ unsigned int pci_scan_child_bus(struct pci_bus *bus) max = pci_scan_bridge(bus, dev, max, pass); } + /* + * Make sure a hotplug bridge has at least the minimum requested + * number of buses. + */ + if (bus->self && bus->self->is_hotplug_bridge && pci_hotplug_bus_size) { + if (max - bus->busn_res.start < pci_hotplug_bus_size - 1) + max = bus->busn_res.start + pci_hotplug_bus_size - 1; + } + /* * We've scanned the bus and so we know all about what's on * the other side of any bridges that may be on this bus plus diff --git a/include/linux/pci.h b/include/linux/pci.h index b67e4df20801..0c283254111d 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1706,6 +1706,7 @@ extern u8 pci_cache_line_size; extern unsigned long pci_hotplug_io_size; extern unsigned long pci_hotplug_mem_size; +extern unsigned long pci_hotplug_bus_size; /* Architecture-specific versions may override these (weak) */ void pcibios_disable_device(struct pci_dev *dev); -- cgit v1.2.3