[AGPGART] Don't clobber other bits in control register when flushing TLB on VIA.

Signed-off-by: Dave Jones <davej@redhat.com>

drivers/char/agp/via-agp.c

@@ -79,8 +79,13 @@ static void via_cleanup(void)
 
 static void via_tlbflush(struct agp_memory *mem)
 {
-	pci_write_config_dword(agp_bridge->dev, VIA_GARTCTRL, 0x0000008f);
-	pci_write_config_dword(agp_bridge->dev, VIA_GARTCTRL, 0x0000000f);
+	u32 temp;
+
+	pci_read_config_dword(agp_bridge->dev, VIA_GARTCTRL, &temp);
+	temp |= (1<<7);
+	pci_write_config_dword(agp_bridge->dev, VIA_GARTCTRL, temp);
+	temp &= ~(1<<7);
+	pci_write_config_dword(agp_bridge->dev, VIA_GARTCTRL, temp);
 }