This is a note to let you know that I've just added the patch titled
drm/ast: Fix ARM compatibility
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-ast-fix-arm-compatibility.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit d6bc55452094218c29325d7983b8680563190ac2
Author: Jammy Huang <jammy_huang@xxxxxxxxxxxxxx>
Date: Fri Apr 21 08:33:54 2023 +0800
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@xxxxxxxxxxxxxx>
Reviewed-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20230421003354.27767-1-jammy_huang@xxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/ast/ast_main.c b/drivers/gpu/drm/ast/ast_main.c
index 79a3618679554..754a08c92d3d1 100644
--- a/drivers/gpu/drm/ast/ast_main.c
+++ b/drivers/gpu/drm/ast/ast_main.c
@@ -423,11 +423,12 @@ 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;
}
