drm/ast: Fixed vram size incorrect issue on POWER

The default value of VGA scratch may incorrect.
Should initial h/w before get vram info.

Acked-by: Joel Stanley <joel@jms.id.au>
Tested-by: Y.C. Chen <yc_chen@aspeedtech.com>
Signed-off-by: Y.C. Chen <yc_chen@aspeedtech.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/ast/ast_main.c

@@ -518,6 +518,9 @@ int ast_driver_load(struct drm_device *dev, unsigned long flags)
 
 	ast_detect_chip(dev, &need_post);
 
+	if (need_post)
+		ast_post_gpu(dev);
+
 	if (ast->chip != AST1180) {
 		ret = ast_get_dram_info(dev);
 		if (ret)
@@ -528,9 +531,6 @@ int ast_driver_load(struct drm_device *dev, unsigned long flags)
 			 ast->dram_bus_width, ast->vram_size);
 	}
 
-	if (need_post)
-		ast_post_gpu(dev);
-
 	ret = ast_mm_init(ast);
 	if (ret)
 		goto out_free;

drivers/gpu/drm/ast/ast_post.c

@@ -79,7 +79,7 @@ ast_set_def_ext_reg(struct drm_device *dev)
 	const u8 *ext_reg_info;
 
 	/* reset scratch */
-	for (i = 0x81; i <= 0x8f; i++)
+	for (i = 0x81; i <= 0x9f; i++)
 		ast_set_index_reg(ast, AST_IO_CRTC_PORT, i, 0x00);
 
 	if (ast->chip == AST2300 || ast->chip == AST2400) {