[AGP] Use compatability mode of KT400 if detected

drivers/char/agp/agp.h

@@ -291,6 +291,9 @@ struct agp_bridge_data {
 #define VIA_APSIZE	0x84
 #define VIA_ATTBASE	0x88
 
+/* VIA KT400 */
+#define VIA_AGPSEL	0xfd
+
 /* SiS registers */
 #define SIS_APBASE	0x10
 #define SIS_ATTBASE	0x90

drivers/char/agp/via-agp.c

@@ -125,14 +125,23 @@ static int __init via_generic_setup (struct pci_dev *pdev)
 }
 
 
+/*
+ * The KT400 does magick to put the AGP bridge compliant with the same
+ * standards version as the graphics card. If we haven't fallen into
+ * 2.0 compatability mode, we run the normal 3.0 code, and fall back
+ * if something nasty happens.
+ */
 static void via_kt400_enable(u32 mode)
 {
-	if ((agp_generic_agp_3_0_enable)==FALSE)
-	        agp_generic_agp_enable(mode);
+	if ((agp_generic_agp_3_0_enable(mode))==FALSE)
+		/* Something weird happened, fall back to 2.0 */
+		agp_generic_agp_enable(mode);
 }
 
 static int __init via_kt400_setup(struct pci_dev *pdev)
 {
+	u8 reg;
+
 	agp_bridge.masks = via_generic_masks;
 	agp_bridge.num_of_masks = 1;
 	agp_bridge.aperture_sizes = (void *) via_generic_sizes;
@@ -145,7 +154,6 @@ static int __init via_kt400_setup(struct pci_dev *pdev)
 	agp_bridge.cleanup = via_cleanup;
 	agp_bridge.tlb_flush = via_tlbflush;
 	agp_bridge.mask_memory = via_mask_memory;
-	agp_bridge.agp_enable = agp_generic_agp_enable;
 	agp_bridge.cache_flush = global_cache_flush;
 	agp_bridge.create_gatt_table = agp_generic_create_gatt_table;
 	agp_bridge.free_gatt_table = agp_generic_free_gatt_table;
@@ -158,16 +166,22 @@ static int __init via_kt400_setup(struct pci_dev *pdev)
 	agp_bridge.suspend = agp_generic_suspend;
 	agp_bridge.resume = agp_generic_resume;
 	agp_bridge.cant_use_aperture = 0;
+
+	pci_read_config_byte(agp_bridge.dev, VIA_AGPSEL, &reg);
+	if ((reg & (1<<1))==1) {
+		/* AGP 2.0 compatability mode. */
+		agp_bridge.agp_enable = agp_generic_agp_enable;
+
+	} else {
+
+		/* AGP 3.0 mode */
+		agp_bridge.agp_enable = via_kt400_enable;
+	}
 	return 0;
 }
 
 static struct agp_device_ids via_agp_device_ids[] __initdata =
 {
-	{
-		.device_id	= PCI_DEVICE_ID_VIA_8501_0,
-		.chipset	= VIA_MVP4,
-		.chipset_name	= "MVP4",
-	},
 	{
 		.device_id	= PCI_DEVICE_ID_VIA_82C597_0,
 		.chipset	= VIA_VP3,
@@ -178,6 +192,11 @@ static struct agp_device_ids via_agp_device_ids[] __initdata =
 		.chipset	= VIA_MVP3,
 		.chipset_name	= "MVP3",
 	},
+	{
+		.device_id	= PCI_DEVICE_ID_VIA_8501_0,
+		.chipset	= VIA_MVP4,
+		.chipset_name	= "MVP4",
+	},
 	{
 		.device_id	= PCI_DEVICE_ID_VIA_82C691,
 		.chipset	= VIA_APOLLO_PRO,
@@ -203,6 +222,11 @@ static struct agp_device_ids via_agp_device_ids[] __initdata =
 		.chipset	= VIA_APOLLO_KT133,
 		.chipset_name	= "Apollo Pro KT266",
 	},
+	{
+		.device_id	= PCI_DEVICE_ID_VIA_8653_0,
+		.chipset	= VIA_APOLLO_PRO,
+		.chipset_name	= "Apollo Pro 266T",
+	},
 	{
 		.device_id	= PCI_DEVICE_ID_VIA_8377_0,
 		.chipset	= VIA_APOLLO_KT400,
@@ -210,14 +234,10 @@ static struct agp_device_ids via_agp_device_ids[] __initdata =
 		.chipset_setup	= via_kt400_setup,
 	},
 	{
-		.device_id	= PCI_DEVICE_ID_VIA_8653_0,
-		.chipset	= VIA_APOLLO_PRO,
-		.chipset_name	= "Apollo Pro266T",
-	},
-	{
+		/* VIA ProSavage PM133 (Apollo Pro133A chipset with S3 Savage4) */
 		.device_id	= PCI_DEVICE_ID_VIA_82C694X_0,
 		.chipset	= VIA_VT8605,
-		.chipset_name	= "PM133"
+		.chipset_name	= "Apollo ProSavage PM133"
 	},
 	{ }, /* dummy final entry, always present */
 };