3 files changed, 34 insertions, 0 deletions

diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c
index 6fdb3ec30c31..55253095be84 100644
--- a/arch/x86/pci/i386.c
+++ b/arch/x86/pci/i386.c
@@ -184,6 +184,7 @@ static void __init pcibios_allocate_resources(int pass)
                                         idx, r, disabled, pass);
                                 if (pci_claim_resource(dev, idx) < 0) {
                                         /* We'll assign a new address later */
+                                        dev->fw_addr[idx] = r->start;
                                         r->end -= r->start;
                                         r->start = 0;
                                 }
diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index 92379e2d37e7..2aaa13150de3 100644
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -156,6 +156,38 @@ static int __pci_assign_resource(struct pci_bus *bus, struct pci_dev *dev,
                                              pcibios_align_resource, dev);
         }
 
+        if (ret < 0 && dev->fw_addr[resno]) {
+                struct resource *root, *conflict;
+                resource_size_t start, end;
+
+                /*
+                 * If we failed to assign anything, let's try the address
+                 * where firmware left it.  That at least has a chance of
+                 * working, which is better than just leaving it disabled.
+                 */
+
+                if (res->flags & IORESOURCE_IO)
+                        root = &ioport_resource;
+                else
+                        root = &iomem_resource;
+
+                start = res->start;
+                end = res->end;
+                res->start = dev->fw_addr[resno];
+                res->end = res->start + size - 1;
+                dev_info(&dev->dev, "BAR %d: trying firmware assignment %pR\n",
+                         resno, res);
+                conflict = request_resource_conflict(root, res);
+                if (conflict) {
+                        dev_info(&dev->dev,
+                                 "BAR %d: %pR conflicts with %s %pR\n", resno,
+                                 res, conflict->name, conflict);
+                        res->start = start;
+                        res->end = end;
+                } else
+                        ret = 0;
+        }
+
         if (!ret) {
                 res->flags &= ~IORESOURCE_STARTALIGN;
                 dev_info(&dev->dev, "BAR %d: assigned %pR\n", resno, res);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 7cb00845f150..f26fda76b87f 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -288,6 +288,7 @@ struct pci_dev {
          */
         unsigned int    irq;
         struct resource resource[DEVICE_COUNT_RESOURCE]; /* I/O and memory regions + expansion ROMs */
+        resource_size_t fw_addr[DEVICE_COUNT_RESOURCE]; /* FW-assigned addr */
 
         /* These fields are used by common fixups */
         unsigned int    transparent:1;  /* Transparent PCI bridge */