drm/ast: Fix ARM compatibility

[ Upstream commit 4327a6137ed43a091d900b1ac833345d60f32228 ]

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

Signed-off-by: Jammy Huang <jammy_huang@aspeedtech.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230421003354.27767-1-jammy_huang@aspeedtech.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/ast/ast_main.c b/drivers/gpu/drm/ast/ast_main.c
index 0674532..5df5270 100644 (file)
--- a/drivers/gpu/drm/ast/ast_main.c
+++ b/drivers/gpu/drm/ast/ast_main.c
@@ -427,11 +427,12 @@ 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;
        }