PCI: ignore failure to preallocate minimal resources to hotplug bridges Linux tries to pre-allocate minimal resources to hotplug bridges. This works fine as long as there are enough resources to satisfy all other genuine resource requirements. However if enough resources are not available to satisfy the pre-allocation, the resource-allocator reports errors and returns failure. This patch distinguishes between must-need resources and nice-to-have resources. Any failure to allocate nice-to-have resources are ignored. This behavior can be particularly useful to trigger automatic reallocation, if the OS discovers genuine resource allocation conflicts or genuine unallocated BARs caused by not-so-smart allocation behavior of the native BIOS. The motivation for this patch is due a issue reported in https://bugzilla.kernel.org/show_bug.cgi?id=15960 Signed-off-by: Ram Pai <linuxram@xxxxxxxxxx> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c index 66cb8f4..3bbc427 100644 --- a/drivers/pci/setup-bus.c +++ b/drivers/pci/setup-bus.c @@ -412,14 +412,14 @@ static void pbus_size_io(struct pci_bus *bus, resource_size_t min_size) { struct pci_dev *dev; struct resource *b_res = find_free_bus_resource(bus, IORESOURCE_IO); - unsigned long size = 0, size1 = 0, old_size; + unsigned long size = 0, size1 = 0, old_size, dev_present=0; if (!b_res) return; list_for_each_entry(dev, &bus->devices, bus_list) { int i; - + dev_present=1; for (i = 0; i < PCI_NUM_RESOURCES; i++) { struct resource *r = &dev->resource[i]; unsigned long r_size; @@ -460,6 +460,12 @@ static void pbus_size_io(struct pci_bus *bus, resource_size_t min_size) b_res->start = 4096; b_res->end = b_res->start + size - 1; b_res->flags |= IORESOURCE_STARTALIGN; + + /* if no devices are behind this bus, inform + * resource-allocater to try hard but not to worry + * if allocations fail + */ + b_res->flags |= (!dev_present) ? IORESOURCE_IGNORE_FAIL : 0; } /* Calculate the size of the bus and minimal alignment which @@ -470,7 +476,7 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask, struct pci_dev *dev; resource_size_t min_align, align, size, old_size; resource_size_t aligns[12]; /* Alignments from 1Mb to 2Gb */ - int order, max_order; + int order, max_order, dev_present=0; struct resource *b_res = find_free_bus_resource(bus, type); unsigned int mem64_mask = 0; @@ -487,6 +493,7 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask, list_for_each_entry(dev, &bus->devices, bus_list) { int i; + dev_present=1; for (i = 0; i < PCI_NUM_RESOURCES; i++) { struct resource *r = &dev->resource[i]; resource_size_t r_size; @@ -550,6 +557,13 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask, b_res->end = size + min_align - 1; b_res->flags |= IORESOURCE_STARTALIGN; b_res->flags |= mem64_mask; + + /* if no devices are behind this bus, inform + * resource-allocater to try hard but not to worry + * if allocations fail + */ + b_res->flags |= (!dev_present) ? IORESOURCE_IGNORE_FAIL : 0; + return 1; } diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c index 2aaa131..a8ce953 100644 --- a/drivers/pci/setup-res.c +++ b/drivers/pci/setup-res.c @@ -210,7 +210,8 @@ int pci_assign_resource(struct pci_dev *dev, int resno) if (!align) { dev_info(&dev->dev, "BAR %d: can't assign %pR " "(bogus alignment)\n", resno, res); - return -EINVAL; + ret = -EINVAL; + goto out; } bus = dev->bus; @@ -225,6 +226,10 @@ int pci_assign_resource(struct pci_dev *dev, int resno) } if (ret) { + if (res->flags & IORESOURCE_IGNORE_FAIL) { + ret = 0; + goto out; + } if (res->flags & IORESOURCE_MEM) if (res->flags & IORESOURCE_PREFETCH) type = "mem pref"; @@ -239,6 +244,8 @@ int pci_assign_resource(struct pci_dev *dev, int resno) resno, type, (unsigned long long) resource_size(res)); } +out: + res->flags &= ~IORESOURCE_IGNORE_FAIL; return ret; } diff --git a/include/linux/ioport.h b/include/linux/ioport.h index b227902..941624b 100644 --- a/include/linux/ioport.h +++ b/include/linux/ioport.h @@ -49,6 +49,7 @@ struct resource_list { #define IORESOURCE_SIZEALIGN 0x00040000 /* size indicates alignment */ #define IORESOURCE_STARTALIGN 0x00080000 /* start field is alignment */ +#define IORESOURCE_IGNORE_FAIL 0x00800000 /* IGNORE if allocation fail*/ #define IORESOURCE_MEM_64 0x00100000 #define IORESOURCE_WINDOW 0x00200000 /* forwarded by bridge */ -- 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
