4 files changed, 38 insertions, 11 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 7fb7a4b161ff..7dc523e082a2 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2109,8 +2109,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                                 the default.
                                 off: Turn ECRC off
                                 on: Turn ECRC on.
-                realloc         reallocate PCI resources if allocations done by BIOS
-                                are erroneous.
+                realloc=        Enable/disable reallocating PCI bridge resources
+                                if allocations done by BIOS are too small to
+                                accommodate resources required by all child
+                                devices.
+                                off: Turn realloc off
+                                on: Turn realloc on
+                realloc         same as realloc=on
 
         pcie_aspm=      [PCIE] Forcibly enable or disable PCIe Active State Power
                         Management.
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 8f30736dbf3f..e9f9dc183cfc 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3772,8 +3772,10 @@ static int __init pci_setup(char *str)
                                 pci_no_msi();
                         } else if (!strcmp(str, "noaer")) {
                                 pci_no_aer();
+                        } else if (!strncmp(str, "realloc=", 8)) {
+                                pci_realloc_get_opt(str + 8);
                         } else if (!strncmp(str, "realloc", 7)) {
-                                pci_realloc();
+                                pci_realloc_get_opt("on");
                         } else if (!strcmp(str, "nodomains")) {
                                 pci_no_domains();
                         } else if (!strncmp(str, "cbiosize=", 9)) {
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 586ac9b097e4..1fc63b39f83f 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -149,7 +149,7 @@ static inline void pci_no_msi(void) { }
 static inline void pci_msi_init_pci_dev(struct pci_dev *dev) { }
 #endif
 
-extern void pci_realloc(void);
+void pci_realloc_get_opt(char *);
 
 static inline int pci_no_d1d2(struct pci_dev *dev)
 {
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 162edfb356b6..219722df68d6 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -48,13 +48,6 @@ static void free_list(struct list_head *head)
         }
 }
 
-int pci_realloc_enable = 0;
-#define pci_realloc_enabled() pci_realloc_enable
-void pci_realloc(void)
-{
-        pci_realloc_enable = 1;
-}
-
 /**
  * add_to_list() - add a new resource tracker to the list
  * @head:       Head of the list
@@ -1273,6 +1266,33 @@ static int __init pci_get_max_depth(void)
         return depth;
 }
 
+/*
+ * -1: undefined, will auto detect later
+ *  0: disabled by user
+ *  1: disabled by auto detect
+ *  2: enabled by user
+ *  3: enabled by auto detect
+ */
+enum enable_type {
+        undefined = -1,
+        user_disabled,
+        auto_disabled,
+        user_enabled,
+        auto_enabled,
+};
+
+static enum enable_type pci_realloc_enable __initdata = undefined;
+void __init pci_realloc_get_opt(char *str)
+{
+        if (!strncmp(str, "off", 3))
+                pci_realloc_enable = user_disabled;
+        else if (!strncmp(str, "on", 2))
+                pci_realloc_enable = user_enabled;
+}
+static bool __init pci_realloc_enabled(void)
+{
+        return pci_realloc_enable >= user_enabled;
+}
 
 /*
  * first try will not touch pci bridge res