drm/ast: Fix ARM compatibility

jira LE-1907
Rebuild_History Non-Buildable kernel-5.14.0-284.30.1.el9_2
commit-author Jammy Huang <[email protected]>
commit 4327a61

ARM architecture only has 'memory', so all devices are accessed by
MMIO if possible.

	Signed-off-by: Jammy Huang <[email protected]>
	Reviewed-by: Thomas Zimmermann <[email protected]>
	Signed-off-by: Thomas Zimmermann <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
(cherry picked from commit 4327a61)
	Signed-off-by: Jonathan Maple <[email protected]>

Author: PlaidCat

drivers/gpu/drm/ast/ast_main.c

@@ -426,11 +426,12 @@ struct ast_private *ast_device_create(const struct drm_driver *drv,
 		return ERR_PTR(-EIO);
 
 	/*
-	 * If we don't have IO space at all, use MMIO now and
-	 * assume the chip has MMIO enabled by default (rev 0x20
-	 * and higher).
+	 * After AST2500, MMIO is enabled by default, and it should be adopted
+	 * to be compatible with Arm.
 	 */
-	if (!(pci_resource_flags(pdev, 2) & IORESOURCE_IO)) {
+	if (pdev->revision >= 0x40) {
+		ast->ioregs = ast->regs + AST_IO_MM_OFFSET;
+	} else if (!(pci_resource_flags(pdev, 2) & IORESOURCE_IO)) {
 		drm_info(dev, "platform has no IO space, trying MMIO\n");
 		ast->ioregs = ast->regs + AST_IO_MM_OFFSET;
 	}