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, 9 insertions, 13 deletions

diff --git a/arch/x86/pci/mmconfig_32.c b/arch/x86/pci/mmconfig_32.c
index 1bf5816d34c..7b75e651343 100644
--- a/arch/x86/pci/mmconfig_32.c
+++ b/arch/x86/pci/mmconfig_32.c
@@ -30,10 +30,6 @@ static u32 get_base_addr(unsigned int seg, int bus, unsigned devfn)
         struct acpi_mcfg_allocation *cfg;
         int cfg_num;
 
-        if (seg == 0 && bus < PCI_MMCFG_MAX_CHECK_BUS &&
-            test_bit(PCI_SLOT(devfn) + 32*bus, pci_mmcfg_fallback_slots))
-                return 0;
-
         for (cfg_num = 0; cfg_num < pci_mmcfg_config_num; cfg_num++) {
                 cfg = &pci_mmcfg_config[cfg_num];
                 if (cfg->pci_segment == seg &&
@@ -68,13 +64,16 @@ static int pci_mmcfg_read(unsigned int seg, unsigned int bus,
         u32 base;
 
         if ((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);
+
         base = get_base_addr(seg, bus, devfn);
         if (!base)
-                return pci_conf1_read(seg,bus,devfn,reg,len,value);
+                goto err;
 
         spin_lock_irqsave(&pci_config_lock, flags);
 
@@ -105,9 +104,12 @@ static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
         if ((bus > 255) || (devfn > 255) || (reg > 4095))
                 return -EINVAL;
 
+        if (reg < 256)
+                return pci_conf1_write(seg,bus,devfn,reg,len,value);
+
         base = get_base_addr(seg, bus, devfn);
         if (!base)
-                return pci_conf1_write(seg,bus,devfn,reg,len,value);
+                return -EINVAL;
 
         spin_lock_irqsave(&pci_config_lock, flags);
 
@@ -134,12 +136,6 @@ static struct pci_raw_ops pci_mmcfg = {
         .write =        pci_mmcfg_write,
 };
 
-int __init pci_mmcfg_arch_reachable(unsigned int seg, unsigned int bus,
-                                    unsigned int devfn)
-{
-        return get_base_addr(seg, bus, devfn) != 0;
-}
-
 int __init pci_mmcfg_arch_init(void)
 {
         printk(KERN_INFO "PCI: Using MMCONFIG\n");