drm/ast: Use managed interfaces for framebuffer write combining

Replace arch_phys_wc_add() and arch_io_reserve_memtype_wc() with
the rsp managed functions. Allows for removing the cleanup code
for memory management
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210916181601.9146-4-tzimmermann@suse.de

drivers/gpu/drm/ast/ast_drv.h

@@ -158,8 +158,6 @@ struct ast_private {
 	uint32_t dram_type;
 	uint32_t mclk;
 
-	int fb_mtrr;
-
 	struct drm_plane primary_plane;
 	struct ast_cursor_plane cursor_plane;
 	struct drm_crtc crtc;

drivers/gpu/drm/ast/ast_mm.c

@@ -74,35 +74,28 @@ static u32 ast_get_vram_size(struct ast_private *ast)
 	return vram_size;
 }
 
-static void ast_mm_release(struct drm_device *dev, void *ptr)
-{
-	struct ast_private *ast = to_ast_private(dev);
-	struct pci_dev *pdev = to_pci_dev(dev->dev);
-
-	arch_phys_wc_del(ast->fb_mtrr);
-	arch_io_free_memtype_wc(pci_resource_start(pdev, 0),
-				pci_resource_len(pdev, 0));
-}
-
 int ast_mm_init(struct ast_private *ast)
 {
 	struct drm_device *dev = &ast->base;
 	struct pci_dev *pdev = to_pci_dev(dev->dev);
+	resource_size_t base, size;
 	u32 vram_size;
 	int ret;
 
+	base = pci_resource_start(pdev, 0);
+	size = pci_resource_len(pdev, 0);
+
+	/* Don't fail on errors, but performance might be reduced. */
+	devm_arch_io_reserve_memtype_wc(dev->dev, base, size);
+	devm_arch_phys_wc_add(dev->dev, base, size);
+
 	vram_size = ast_get_vram_size(ast);
 
-	ret = drmm_vram_helper_init(dev, pci_resource_start(pdev, 0), vram_size);
+	ret = drmm_vram_helper_init(dev, base, vram_size);
 	if (ret) {
 		drm_err(dev, "Error initializing VRAM MM; %d\n", ret);
 		return ret;
 	}
 
-	arch_io_reserve_memtype_wc(pci_resource_start(pdev, 0),
-				   pci_resource_len(pdev, 0));
-	ast->fb_mtrr = arch_phys_wc_add(pci_resource_start(pdev, 0),
-					pci_resource_len(pdev, 0));
-
-	return drmm_add_action_or_reset(dev, ast_mm_release, NULL);
+	return 0;
 }