agp: add user mapping support to ATI AGP bridge.

This should fix TTM/KMS on some of the original ATI IGP chipsets.
(rs100/rs200)
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/char/agp/ati-agp.c

@@ -269,12 +269,17 @@ static int ati_insert_memory(struct agp_memory * mem,
 	int i, j, num_entries;
 	unsigned long __iomem *cur_gatt;
 	unsigned long addr;
+	int mask_type;
 
 	num_entries = A_SIZE_LVL2(agp_bridge->current_size)->num_entries;
 
-	if (type != 0 || mem->type != 0)
+	mask_type = agp_generic_type_to_mask_type(mem->bridge, type);
+	if (mask_type != 0 || type != mem->type)
 		return -EINVAL;
 
+	if (mem->page_count == 0)
+		return 0;
+
 	if ((pg_start + mem->page_count) > num_entries)
 		return -EINVAL;
 
@@ -299,8 +304,8 @@ static int ati_insert_memory(struct agp_memory * mem,
 		writel(agp_bridge->driver->mask_memory(agp_bridge,	
 						       mem->pages[i], mem->type),
 		       cur_gatt+GET_GATT_OFF(addr));
-		readl(cur_gatt+GET_GATT_OFF(addr));	/* PCI Posting. */
 	}
+	readl(GET_GATT(agp_bridge->gart_bus_addr)); /* PCI posting */
 	agp_bridge->driver->tlb_flush(mem);
 	return 0;
 }
@@ -311,17 +316,22 @@ static int ati_remove_memory(struct agp_memory * mem, off_t pg_start,
 	int i;
 	unsigned long __iomem *cur_gatt;
 	unsigned long addr;
+	int mask_type;
 
-	if (type != 0 || mem->type != 0)
+	mask_type = agp_generic_type_to_mask_type(mem->bridge, type);
+	if (mask_type != 0 || type != mem->type)
 		return -EINVAL;
 
+	if (mem->page_count == 0)
+		return 0;
+
 	for (i = pg_start; i < (mem->page_count + pg_start); i++) {
 		addr = (i * PAGE_SIZE) + agp_bridge->gart_bus_addr;
 		cur_gatt = GET_GATT(addr);
 		writel(agp_bridge->scratch_page, cur_gatt+GET_GATT_OFF(addr));
-		readl(cur_gatt+GET_GATT_OFF(addr)); /* PCI Posting. */
 	}
 
+	readl(GET_GATT(agp_bridge->gart_bus_addr)); /* PCI posting */
 	agp_bridge->driver->tlb_flush(mem);
 	return 0;
 }