From: Keith Busch Date: Fri, 22 Jul 2016 03:40:28 +0000 (-0600) Subject: PCI: Allow additional bus numbers for hotplug bridges X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=e16b46605960bd071a3e26f316e0bb600ae91e37;p=linux-beck.git 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 --- 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);