Re-apply Dave's VIA quirk update from 2.4.x

after the manual merge of the PCI re-organization
removed it.

diff --git a/arch/i386/kernel/pci/fixup.c b/arch/i386/kernel/pci/fixup.c
index ca14f00c7abed1477c054b1cbbf1168b47886ab6..372f2f342a4fd74f6a5cd9f4310f0e858284f1a0 100644 (file)
--- a/arch/i386/kernel/pci/fixup.c
+++ b/arch/i386/kernel/pci/fixup.c
@@ -119,28 +119,48 @@ static void __devinit pci_fixup_piix4_acpi(struct pci_dev *d)
 
 /*
  * Addresses issues with problems in the memory write queue timer in
- * certain VIA Northbridges.  This bugfix is per VIA's specifications.
+ * certain VIA Northbridges.  This bugfix is per VIA's specifications,
+ * except for the KL133/KM133: clearing bit 5 on those Northbridges seems
+ * to trigger a bug in its integrated ProSavage video card, which
+ * causes screen corruption.  We only clear bits 6 and 7 for that chipset,
+ * until VIA can provide us with definitive information on why screen
+ * corruption occurs, and what exactly those bits do.
  *
  * VIA 8363,8622,8361 Northbridges:
  *  - bits  5, 6, 7 at offset 0x55 need to be turned off
  * VIA 8367 (KT266x) Northbridges:
  *  - bits  5, 6, 7 at offset 0x95 need to be turned off
+ * VIA 8363 rev 0x81/0x84 (KL133/KM133) Northbridges:
+ *  - bits     6, 7 at offset 0x55 need to be turned off
  */
+
+#define VIA_8363_KL133_REVISION_ID 0x81
+#define VIA_8363_KM133_REVISION_ID 0x84
+
 static void __init pci_fixup_via_northbridge_bug(struct pci_dev *d)
 {
        u8 v;
+       u8 revision;
        int where = 0x55;
+       int mask = 0x1f; /* clear bits 5, 6, 7 by default */
+
+       pci_read_config_byte(d, PCI_REVISION_ID, &revision);
 
        if (d->device == PCI_DEVICE_ID_VIA_8367_0) {
                where = 0x95; /* the memory write queue timer register is 
-                                 different for the kt266x's: 0x95 not 0x55 */
+                               different for the KT266x's: 0x95 not 0x55 */
+       } else if (d->device == PCI_DEVICE_ID_VIA_8363_0 &&
+                       (revision == VIA_8363_KL133_REVISION_ID || 
+                       revision == VIA_8363_KM133_REVISION_ID)) {
+                       mask = 0x3f; /* clear only bits 6 and 7; clearing bit 5
+                                       causes screen corruption on the KL133/KM133 */
        }
 
         pci_read_config_byte(d, where, &v);
-       if (v & 0xe0) {
-               printk(KERN_WARNING "Disabling broken memory write queue: [%02x] %02x->%02x\n",
-                       where, v, v & 0x1f);
-               v &= 0x1f; /* clear bits 5, 6, 7 */
+       if (v & ~mask) {
+               printk(KERN_WARNING "Disabling VIA memory write queue (PCI ID %04x, rev %02x): [%02x] %02x & %02x -> %02x\n", \
+                       d->device, revision, where, v, mask, v & mask);
+               v &= mask;
                pci_write_config_byte(d, where, v);
        }
 }