From e66ab84fa74daee2b24acad9bbba62b00d97b762 Mon Sep 17 00:00:00 2001
From: vhaudiquet <vhaudiquet@localhost>
Date: Sun, 30 Aug 2026 16:10:36 +0200
Subject: [PATCH] WIP (temporary): bind/probe checkpoints in scanout driver and
 video uclass

---
 drivers/video/mt8183_scanout.c | 40 ++++++++++++++++++++++++++++++----
 drivers/video/video-uclass.c   | 21 ++++++++++++++++++
 2 files changed, 57 insertions(+), 4 deletions(-)

diff --git a/drivers/video/mt8183_scanout.c b/drivers/video/mt8183_scanout.c
index dc342b93e2c..26eb385cd64 100644
--- a/drivers/video/mt8183_scanout.c
+++ b/drivers/video/mt8183_scanout.c
@@ -40,6 +40,27 @@
 #define DISP_REG_OVL_EN		0x000c
 #define DISP_REG_OVL0_2L_EN	0x100c
 
+/* TEMPORARY bring-up diagnostics (krane Round 24) — do not upstream:
+ * paint a band into the live depthcharge scanout. */
+static void krane_diag_band(u32 y0, u32 rows, u32 color)
+{
+	u32 base = readl((void __iomem *)0x14008f40);
+	u32 *p, n = rows * 1200, i;
+
+	if (base < 0x40000000)
+		return;
+
+	if (dcache_status())
+		mmu_map_region(base, 0x8ca000, false);
+
+	p = (u32 *)(uintptr_t)(base + (u64)y0 * 4800);
+	for (i = 0; i < n; i++)
+		p[i] = color;
+
+	if (dcache_status())
+		flush_dcache_range((uintptr_t)p, (uintptr_t)(p + n));
+}
+
 /*
  * Backlight GPIOs. The MT8183 GPIO controller is at 0x10005000; the dout
  * block starts at +0x100 with 16 bytes per 32-pin group and set@+4 (layout
@@ -147,9 +168,13 @@ static int mt8183_scanout_probe(struct udevice *dev)
 	u64 addr;
 	int ret;
 
+	krane_diag_band(500, 40, 0x00ff00ff);	/* magenta: probe entered */
+
 	ovl = dev_read_addr(dev);
-	if (ovl == FDT_ADDR_T_NONE)
+	if (ovl == FDT_ADDR_T_NONE) {
+		krane_diag_band(780, 40, 0x00ff0000);	/* red: ovl read failed */
 		return log_msg_ret("ovl", -EINVAL);
+	}
 
 	/*
 	 * Revive the pipeline: undo depthcharge's display_cleanup() by
@@ -171,13 +196,17 @@ static int mt8183_scanout_probe(struct udevice *dev)
 	mmu_map_region(COREBOOT_TABLE_ADDR, SZ_4K, false);
 
 	ret = find_framebuffer(COREBOOT_TABLE_ADDR, &fb);
-	if (ret)
+	if (ret) {
+		krane_diag_band(800, 40, 0x00ff0000);	/* red: lbio failed */
 		return log_msg_ret("lbio", ret);
+	}
 
 	if (fb.bits_per_pixel != 32 || fb.red_pos != 16 || fb.red_size != 8 ||
 	    fb.green_pos != 8 || fb.green_size != 8 ||
-	    fb.blue_pos != 0 || fb.blue_size != 8)
+	    fb.blue_pos != 0 || fb.blue_size != 8) {
+		krane_diag_band(820, 40, 0x00ff0000);	/* red: fmt mismatch */
 		return log_msg_ret("fmt", -ENOTSUPP);
+	}
 
 	/*
 	 * Use the address from the coreboot table when it is a plausible
@@ -189,8 +218,11 @@ static int mt8183_scanout_probe(struct udevice *dev)
 	if (addr < SZ_1G)
 		addr = readl(ovl + DISP_REG_OVL_L0_ADDR);
 
-	if (addr < SZ_1G)
+	if (addr < SZ_1G) {
+		krane_diag_band(840, 40, 0x00ff0000);	/* red: no scanout addr */
 		return log_msg_ret("scanout", -ENODEV);
+	}
+	krane_diag_band(620, 40, 0x00aaaaaa);	/* gray: geometry resolved */
 
 	plat->base = addr;
 	plat->size = fb.bytes_per_line * fb.y_resolution;
diff --git a/drivers/video/video-uclass.c b/drivers/video/video-uclass.c
index 068653ced8d..9e661c2aa06 100644
--- a/drivers/video/video-uclass.c
+++ b/drivers/video/video-uclass.c
@@ -782,6 +782,27 @@ static int video_post_probe(struct udevice *dev)
 /* Post-relocation, allocate memory for the frame buffer */
 static int video_post_bind(struct udevice *dev)
 {
+	/* TEMPORARY bring-up diagnostics (krane Round 24) — do not upstream:
+	 * purple band = a video device got bound (driver matched the DT
+	 * node); runs before any probe. */
+	{
+		u32 base = readl((void __iomem *)0x14008f40);
+
+		if (base >= 0x40000000) {
+			u32 *p = (u32 *)(uintptr_t)(base + 470ULL * 4800);
+			int i;
+
+			if (dcache_status())
+				mmu_map_region(base, 0x8ca000, false);
+			for (i = 0; i < 30 * 1200; i++)
+				p[i] = 0x008000ff;
+			if (dcache_status())
+				flush_dcache_range((uintptr_t)p,
+						   (uintptr_t)(p + 30 * 1200));
+		}
+	}
+	/* end TEMPORARY diagnostics */
+
 	struct video_uc_priv *uc_priv;
 	ulong addr;
 	ulong size;