x86: Gart: fix breakage due to IOMMU initialization cleanup

This fixes the following breakage of the commit
75f1cdf:

- GART systems that don't AGP with broken BIOS and more than 4GB
  memory are forced to use swiotlb. They can allocate aperture by
  hand and use GART.

- GART systems without GAP must disable GART on shutdown.

- swiotlb usage is forced by the boot option,
  gart_iommu_hole_init() is not called, so we disable GART
  early_gart_iommu_check().

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
LKML-Reference: <1260759135-6450-3-git-send-email-fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/aperture_64.c

@@ -280,7 +280,8 @@ void __init early_gart_iommu_check(void)
 	 * or BIOS forget to put that in reserved.
 	 * try to update e820 to make that region as reserved.
 	 */
-	int i, fix, slot;
+	u32 agp_aper_base = 0, agp_aper_order = 0;
+	int i, fix, slot, valid_agp = 0;
 	u32 ctl;
 	u32 aper_size = 0, aper_order = 0, last_aper_order = 0;
 	u64 aper_base = 0, last_aper_base = 0;
@@ -290,6 +291,8 @@ void __init early_gart_iommu_check(void)
 		return;
 
 	/* This is mostly duplicate of iommu_hole_init */
+	agp_aper_base = search_agp_bridge(&agp_aper_order, &valid_agp);
+
 	fix = 0;
 	for (i = 0; i < ARRAY_SIZE(bus_dev_ranges); i++) {
 		int bus;
@@ -342,10 +345,10 @@ void __init early_gart_iommu_check(void)
 		}
 	}
 
-	if (!fix)
+	if (valid_agp)
 		return;
 
-	/* different nodes have different setting, disable them all at first*/
+	/* disable them all at first */
 	for (i = 0; i < ARRAY_SIZE(bus_dev_ranges); i++) {
 		int bus;
 		int dev_base, dev_limit;
@@ -458,8 +461,6 @@ void __init gart_iommu_hole_init(void)
 
 	if (aper_alloc) {
 		/* Got the aperture from the AGP bridge */
-	} else if (!valid_agp) {
-		/* Do nothing */
 	} else if ((!no_iommu && max_pfn > MAX_DMA32_PFN) ||
 		   force_iommu ||
 		   valid_agp ||

arch/x86/kernel/pci-gart_64.c

@@ -710,7 +710,8 @@ static void gart_iommu_shutdown(void)
 	struct pci_dev *dev;
 	int i;
 
-	if (no_agp)
+	/* don't shutdown it if there is AGP installed */
+	if (!no_agp)
 		return;
 
 	for (i = 0; i < num_k8_northbridges; i++) {