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. This patch allows
a user specify the minimum number of resources to reserve for a hotplug
bridge's subordinate busses so rebooting won't be necessary.
The default is 1, which is equivalent to previous behavior.
Signed-off-by: Keith Busch <keith.busch@xxxxxxxxx>
---
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(+)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 82b42c9..ce4b45b 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
+ space which is reserved for hotplug bridge's
+ bus window. 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 c8b4dbd..7d290f7 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 8e3ef72..9454396 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2077,6 +2077,15 @@ unsigned int pci_scan_child_bus(struct pci_bus *bus)
}
/*
+ * Make sure a hot plug bridge has at least the minimum requested
+ * number of busses.
+ */
+ 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
* any devices.
diff --git a/include/linux/pci.h b/include/linux/pci.h
index b67e4df..0c28325 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);
--
2.7.2
--
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