simpledrm hack to parse ATAGS for dynamic fb address

simpledrm-mtk-atags.patch

diff --git i/drivers/gpu/drm/tiny/simpledrm.c w/drivers/gpu/drm/tiny/simpledrm.c
index 5d9ab8adf8005..78f0b4b8d3df6 100644
--- i/drivers/gpu/drm/tiny/simpledrm.c
+++ w/drivers/gpu/drm/tiny/simpledrm.c
@@ -3,6 +3,7 @@
 #include <linux/aperture.h>
 #include <linux/clk.h>
 #include <linux/of_clk.h>
+#include <linux/of_fdt.h>
 #include <linux/minmax.h>
 #include <linux/of_address.h>
 #include <linux/platform_data/simplefb.h>
@@ -773,6 +774,16 @@ static struct drm_display_mode simpledrm_mode(unsigned int width,
 	return mode;
 }
 
+static int fb_early_init_dt_get_chosen(unsigned long node, const char *uname, int depth,
+				       void *p_ret_node)
+{
+	if (depth != 1 || (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0))
+		return 0;
+
+	*(unsigned long *)p_ret_node = node;
+	return 1;
+}
+
 static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
 							struct platform_device *pdev)
 {
@@ -879,9 +890,29 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
 	 * Memory management
 	 */
 
+	unsigned long node = 0;
+	of_scan_flat_dt(fb_early_init_dt_get_chosen, &node);
+	int size;
+	struct tag_videolfb {
+		u64 fb_base;
+		u32 islcmfound;
+		u32 fps;
+		u32 vram;
+		char lcmname[1];
+	} *videolfb_tag = (struct tag_videolfb *)of_get_flat_dt_prop(node, "atag,videolfb", &size);
+	if (videolfb_tag)
+		pr_err("got mediatek atag,videolfb 0x%08llx\n", videolfb_tag->fb_base);
+	else
+		pr_err("no mediatek atag,videolfb\n");
+
 	if (mem) {
 		void *screen_base;
 
+		if (videolfb_tag) {
+			mem->start = videolfb_tag->fb_base;
+			mem->end = videolfb_tag->fb_base + videolfb_tag->vram;
+		}
+
 		ret = devm_aperture_acquire_for_platform_device(pdev, mem->start,
 								resource_size(mem));
 		if (ret) {
@@ -903,6 +934,11 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
 		if (!res)
 			return ERR_PTR(-EINVAL);
 
+		if (videolfb_tag) {
+			res->start = videolfb_tag->fb_base;
+			res->end = videolfb_tag->fb_base + videolfb_tag->vram;
+		}
+
 		ret = devm_aperture_acquire_for_platform_device(pdev, res->start,
 								resource_size(res));
 		if (ret) {

based on MT8167 and only tested there: https://github.com/deadman96385/android_kernel_lenovo_mt8167s/blob/a9e681a8e4aa612733df79acc360c730f9f791f0/drivers/misc/mediatek/video/mt8167/videox/mtkfb.c