drm/nv50: hopefully handle the DDR2/DDR3 memtype detection somewhat better

M version 2 appears to have a table with some form of memory type info
available.

NVIDIA appear to ignore the table information except for this DDR2/DDR3
case (which has the same value in 0x100714).  My guess is this is due to
some of the supported memory types not being represented in the table.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_drv.h

@@ -909,6 +909,7 @@ extern int  nouveau_mem_init_agp(struct drm_device *);
 extern int  nouveau_mem_reset_agp(struct drm_device *);
 extern void nouveau_mem_close(struct drm_device *);
 extern bool nouveau_mem_flags_valid(struct drm_device *, u32 tile_flags);
+extern int nouveau_mem_vbios_type(struct drm_device *);
 extern struct nouveau_tile_reg *nv10_mem_set_tiling(
 	struct drm_device *dev, uint32_t addr, uint32_t size,
 	uint32_t pitch, uint32_t flags);

drivers/gpu/drm/nouveau/nouveau_mem.c

@@ -683,6 +683,29 @@ nouveau_mem_timing_fini(struct drm_device *dev)
 	}
 }
 
+int
+nouveau_mem_vbios_type(struct drm_device *dev)
+{
+	struct bit_entry M;
+	u8 ramcfg = (nv_rd32(dev, 0x101000) & 0x0000003c) >> 2;
+	if (!bit_table(dev, 'M', &M) || M.version != 2 || M.length < 5) {
+		u8 *table = ROMPTR(dev, M.data[3]);
+		if (table && table[0] == 0x10 && ramcfg < table[3]) {
+			u8 *entry = table + table[1] + (ramcfg * table[2]);
+			switch (entry[0] & 0x0f) {
+			case 0: return NV_MEM_TYPE_DDR2;
+			case 1: return NV_MEM_TYPE_DDR3;
+			case 2: return NV_MEM_TYPE_GDDR3;
+			case 3: return NV_MEM_TYPE_GDDR5;
+			default:
+				break;
+			}
+
+		}
+	}
+	return NV_MEM_TYPE_UNKNOWN;
+}
+
 static int
 nouveau_vram_manager_init(struct ttm_mem_type_manager *man, unsigned long psize)
 {

drivers/gpu/drm/nouveau/nv50_vram.c

@@ -195,10 +195,10 @@ nv50_vram_init(struct drm_device *dev)
 	switch (pfb714 & 0x00000007) {
 	case 0: dev_priv->vram_type = NV_MEM_TYPE_DDR1; break;
 	case 1:
-		if (0 /* some currently unknown condition */)
-			dev_priv->vram_type = NV_MEM_TYPE_DDR2;
-		else
+		if (nouveau_mem_vbios_type(dev) == NV_MEM_TYPE_DDR3)
 			dev_priv->vram_type = NV_MEM_TYPE_DDR3;
+		else
+			dev_priv->vram_type = NV_MEM_TYPE_DDR2;
 		break;
 	case 2: dev_priv->vram_type = NV_MEM_TYPE_GDDR3; break;
 	case 3: dev_priv->vram_type = NV_MEM_TYPE_GDDR4; break;