[PATCH v2 03/14] video: mediatek: add merge component

The merge block is one of the components of the video pipeline on
some MediaTek SoCs, such as the MT8188. It combines two half-width
inputs into one output.

Signed-off-by: Julien Stephan <[email protected]>
---
 drivers/video/mediatek/mtk_disp_merge.c | 106 ++++++++++++++++++++++++++++++++
 drivers/video/mediatek/mtk_disp_merge.h |  19 ++++++
 2 files changed, 125 insertions(+)

diff --git a/drivers/video/mediatek/mtk_disp_merge.c b/drivers/video/mediatek/mtk_disp_merge.c
new file mode 100644
index 00000000000..185e75231fc
--- /dev/null
+++ b/drivers/video/mediatek/mtk_disp_merge.c
@@ -0,0 +1,106 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Mediatek Video Disp Merge Support
+ *
+ * Copyright (c) 2026 BayLibre, SAS.
+ * Author: Julien Stephan <[email protected]>
+ */
+
+#include <dm.h>
+
+#include "mtk_disp_comp.h"
+#include "mtk_disp_merge.h"
+
+/* MERGE registers */
+#define SUBDISP_DISP_MERGE_ENABLE	0x000
+#define SUBDISP_DISP_MERGE_CFG_0	0x010
+#define SUBDISP_DISP_MERGE_CFG_1	0x014
+#define SUBDISP_DISP_MERGE_CFG_4	0x020
+#define SUBDISP_DISP_MERGE_CFG_10	0x038
+#define SUBDISP_DISP_MERGE_CFG_12	0x040
+#define CFG_10_10_2PI_2PO_BUF_MODE	0x08
+#define CFG_11_10_1PI_2PO_MERGE		0x12
+#define SUBDISP_DISP_MERGE_CFG_24	0x070
+#define SUBDISP_DISP_MERGE_CFG_25	0x074
+#define SUBDISP_DISP_MERGE_CFG_26	0x078
+#define SUBDISP_DISP_MERGE_CFG_27	0x07C
+#define SUBDISP_DISP_MERGE_CFG_30	0x088
+#define SUBDISP_DISP_MERGE_MUTE_0	0xf00
+
+void mtk_disp_merge_config(struct udevice *dev,
+			   u16 width1, u16 height1,
+			   u16 width2, u16 height2,
+			   u16 output_width, u16 output_height)
+{
+	bool dual_input = (width2 != 0 && height2 != 0);
+
+	/* input 1 */
+	if (width1 != 0 && height1 != 0)
+		mtk_disp_comp_write(dev, SUBDISP_DISP_MERGE_CFG_0,
+				    height1 << 16 | width1);
+
+	/* input 2 */
+	if (dual_input)
+		mtk_disp_comp_write(dev, SUBDISP_DISP_MERGE_CFG_1,
+				    height2 << 16 | width2);
+
+	/* output */
+	mtk_disp_comp_write(dev, SUBDISP_DISP_MERGE_CFG_4,
+			    output_height << 16 | output_width);
+
+	/* no pixel/channel swap */
+	mtk_disp_comp_write(dev, SUBDISP_DISP_MERGE_CFG_10, 0x0);
+
+	if (dual_input)
+		mtk_disp_comp_write(dev, SUBDISP_DISP_MERGE_CFG_12,
+				    CFG_11_10_1PI_2PO_MERGE);
+	else
+		mtk_disp_comp_write(dev, SUBDISP_DISP_MERGE_CFG_12,
+				    CFG_10_10_2PI_2PO_BUF_MODE);
+
+	/* size in sram of inputs 0 and 1 */
+	if (width1 != 0 && height1 != 0)
+		mtk_disp_comp_write(dev, SUBDISP_DISP_MERGE_CFG_24,
+				    height1 << 16 | width1);
+
+	if (dual_input)
+		mtk_disp_comp_write(dev, SUBDISP_DISP_MERGE_CFG_25,
+				    height2 << 16 | width2);
+	else
+		mtk_disp_comp_write(dev, SUBDISP_DISP_MERGE_CFG_25,
+				    height1 << 16 | width1);
+
+	/* merged size of inputs 0 and 1 */
+	if (width1 != 0 && height1 != 0)
+		mtk_disp_comp_write(dev, SUBDISP_DISP_MERGE_CFG_26,
+				    height1 << 16 | width1);
+
+	if (dual_input)
+		mtk_disp_comp_write(dev, SUBDISP_DISP_MERGE_CFG_27,
+				    height2 << 16 | width2);
+	else
+		mtk_disp_comp_write(dev, SUBDISP_DISP_MERGE_CFG_27,
+				    height1 << 16 | width1);
+
+	/* 12 bit lsb off */
+	mtk_disp_comp_write(dev, SUBDISP_DISP_MERGE_CFG_30, 0x0);
+
+	/* unmute */
+	mtk_disp_comp_write(dev, SUBDISP_DISP_MERGE_MUTE_0, 0x0);
+
+	/* enable */
+	mtk_disp_comp_write(dev, SUBDISP_DISP_MERGE_ENABLE, 0x1);
+}
+
+static const struct udevice_id mtk_disp_merge_ids[] = {
+	{ .compatible = "mediatek,mt8188-disp-merge" },
+	{}
+};
+
+U_BOOT_DRIVER(mtk_disp_merge) = {
+	.name	   = "mtk_disp_merge",
+	.id	   = UCLASS_MISC,
+	.of_match  = mtk_disp_merge_ids,
+	.probe	   = mtk_disp_comp_probe,
+	.priv_auto = sizeof(struct mtk_disp_comp_priv),
+};
diff --git a/drivers/video/mediatek/mtk_disp_merge.h b/drivers/video/mediatek/mtk_disp_merge.h
new file mode 100644
index 00000000000..cac3982c74e
--- /dev/null
+++ b/drivers/video/mediatek/mtk_disp_merge.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Mediatek Video Disp Merge Support
+ *
+ * Copyright (c) 2026 BayLibre, SAS.
+ * Author: Julien Stephan <[email protected]>
+ */
+
+#ifndef _MTK_DISP_MERGE_H
+#define _MTK_DISP_MERGE_H
+
+struct udevice;
+
+void mtk_disp_merge_config(struct udevice *dev,
+			   u16 width1, u16 height1,
+			   u16 width2, u16 height2,
+			   u16 output_width, u16 output_height);
+
+#endif

-- 
2.54.0