--- f67a33c7f4156fd40354bf812b73ddc9a071fdc6
+++ ebdb85cf2686fa36702cd4d50b657f22de85b3bd
@@ -145,10 +145,15 @@ static void __init ati_bugs(int num, int
 
 static u32 __init ati_sbx00_rev(int num, int slot, int func)
 {
-	u32 d;
+	u32 old, d;
 
+	d = read_pci_config(num, slot, func, 0x70);
+	old = d;
+	d &= ~(1<<8);
+	write_pci_config(num, slot, func, 0x70, d);
 	d = read_pci_config(num, slot, func, 0x8);
 	d &= 0xff;
+	write_pci_config(num, slot, func, 0x70, old);
 
 	return d;
 }
@@ -157,19 +162,11 @@ static void __init ati_bugs_contd(int nu
 {
 	u32 d, rev;
 
-	rev = ati_sbx00_rev(num, slot, func);
-	if (rev >= 0x40)
-		acpi_fix_pin2_polarity = 1;
-
-	/*
-	 * SB600: revisions 0x11, 0x12, 0x13, 0x14, ...
-	 * SB700: revisions 0x39, 0x3a, ...
-	 * SB800: revisions 0x40, 0x41, ...
-	 */
-	if (rev >= 0x39)
+	if (acpi_use_timer_override)
 		return;
 
-	if (acpi_use_timer_override)
+	rev = ati_sbx00_rev(num, slot, func);
+	if (rev > 0x13)
 		return;
 
 	/* check for IRQ0 interrupt swap */