PCI x86: always use conf1 to access config space below 256 bytes

Thanks to Loic Prylli <loic@myri.com>, who originally proposed
this idea.

Always using legacy configuration mechanism for the legacy config space
and extended mechanism (mmconf) for the extended config space is
a simple and very logical approach. It's supposed to resolve all
known mmconf problems. It still allows per-device quirks (tweaking
dev->cfg_size). It also allows to get rid of mmconf fallback code.

Signed-off-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 12 deletions

diff --git a/arch/x86/pci/mmconfig_64.c b/arch/x86/pci/mmconfig_64.c
index 4095e4d66a1d..c4cf318e44a9 100644
--- a/arch/x86/pci/mmconfig_64.c
+++ b/arch/x86/pci/mmconfig_64.c
@@ -40,9 +40,7 @@ static char __iomem *get_virt(unsigned int seg, unsigned bus)
 static char __iomem *pci_dev_base(unsigned int seg, unsigned int bus, unsigned int devfn)
 {
         char __iomem *addr;
-        if (seg == 0 && bus < PCI_MMCFG_MAX_CHECK_BUS &&
-                test_bit(32*bus + PCI_SLOT(devfn), pci_mmcfg_fallback_slots))
-                return NULL;
+
         addr = get_virt(seg, bus);
         if (!addr)
                 return NULL;
@@ -56,13 +54,16 @@ static int pci_mmcfg_read(unsigned int seg, unsigned int bus,
 
         /* Why do we have this when nobody checks it. How about a BUG()!? -AK */
         if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095))) {
-                *value = -1;
+err:            *value = -1;
                 return -EINVAL;
         }
 
+        if (reg < 256)
+                return pci_conf1_read(seg,bus,devfn,reg,len,value);
+
         addr = pci_dev_base(seg, bus, devfn);
         if (!addr)
-                return pci_conf1_read(seg,bus,devfn,reg,len,value);
+                goto err;
 
         switch (len) {
         case 1:
@@ -88,9 +89,12 @@ static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
         if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095)))
                 return -EINVAL;
 
+        if (reg < 256)
+                return pci_conf1_write(seg,bus,devfn,reg,len,value);
+
         addr = pci_dev_base(seg, bus, devfn);
         if (!addr)
-                return pci_conf1_write(seg,bus,devfn,reg,len,value);
+                return -EINVAL;
 
         switch (len) {
         case 1:
@@ -126,12 +130,6 @@ static void __iomem * __init mcfg_ioremap(struct acpi_mcfg_allocation *cfg)
         return addr;
 }
 
-int __init pci_mmcfg_arch_reachable(unsigned int seg, unsigned int bus,
-                                    unsigned int devfn)
-{
-        return pci_dev_base(seg, bus, devfn) != NULL;
-}
-
 int __init pci_mmcfg_arch_init(void)
 {
         int i;