[PATCH] VIA quirk update.

Brings up to date with the quirk in 2.4
This makes sure we only apply it on the right chipsets,
and adjusts the bits that get poked depending on which we find.

arch/i386/kernel/pci-pc.c

@@ -1201,28 +1201,48 @@ 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("Disabling broken memory write queue: [%02x] %02x->%02x\n",
-			where, v, v & 0x1f);
-		v &= 0x1f; /* clear bits 5, 6, 7 */
+	if (v & ~mask) {
+		printk("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);
 	}
 }