On Thu, Jul 21, 2016 at 09:40:28PM -0600, Keith Busch wrote:
> 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>
Applied to pci/hotplug for v4.8, thanks, Keith!
> ---
> 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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