[PATCH] Enable write combining for server works LE rev > 6

Enable write combining for server works LE rev > 6 per
http://www.ussg.iu.edu/hypermail/linux/kernel/0104.3/1007.html

Signed-Off-By: Lee Revell <rlrevell@joe-job.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 9 insertions, 5 deletions

diff --git a/arch/i386/kernel/cpu/mtrr/main.c b/arch/i386/kernel/cpu/mtrr/main.c
index 54999e4c55fd..e1c2042b9b7e 100644
--- a/arch/i386/kernel/cpu/mtrr/main.c
+++ b/arch/i386/kernel/cpu/mtrr/main.c
@@ -72,17 +72,21 @@ void set_mtrr_ops(struct mtrr_ops * ops)
 static int have_wrcomb(void)
 {
         struct pci_dev *dev;
+        u8 rev;
         
         if ((dev = pci_get_class(PCI_CLASS_BRIDGE_HOST << 8, NULL)) != NULL) {
-                /* ServerWorks LE chipsets have problems with write-combining 
+                /* ServerWorks LE chipsets < rev 6 have problems with write-combining
                    Don't allow it and leave room for other chipsets to be tagged */
                 if (dev->vendor == PCI_VENDOR_ID_SERVERWORKS &&
                     dev->device == PCI_DEVICE_ID_SERVERWORKS_LE) {
-                        printk(KERN_INFO "mtrr: Serverworks LE detected. Write-combining disabled.\n");
-                        pci_dev_put(dev);
-                        return 0;
+                        pci_read_config_byte(dev, PCI_CLASS_REVISION, &rev);
+                        if (rev <= 5) {
+                                printk(KERN_INFO "mtrr: Serverworks LE rev < 6 detected. Write-combining disabled.\n");
+                                pci_dev_put(dev);
+                                return 0;
+                        }
                 }
-                /* Intel 450NX errata # 23. Non ascending cachline evictions to
+                /* Intel 450NX errata # 23. Non ascending cacheline evictions to
                    write combining memory may resulting in data corruption */
                 if (dev->vendor == PCI_VENDOR_ID_INTEL &&
                     dev->device == PCI_DEVICE_ID_INTEL_82451NX) {