The display mutex synchronizes the components of the video pipeline
on some MediaTek SoCs, such as the MT8188. Only the modules of the
DPI1 pipeline are attached to mutex1; the module bit indices follow
the Linux mtk-mutex driver (MT8188_MUTEX_MOD_DISP1_*).

Signed-off-by: Julien Stephan <[email protected]>
---
 drivers/video/mediatek/mtk_disp_mutex_mt8188.c | 63 ++++++++++++++++++++++++++
 drivers/video/mediatek/mtk_disp_mutex_mt8188.h | 14 ++++++
 2 files changed, 77 insertions(+)

diff --git a/drivers/video/mediatek/mtk_disp_mutex_mt8188.c 
b/drivers/video/mediatek/mtk_disp_mutex_mt8188.c
new file mode 100644
index 00000000000..f7e52cd25bb
--- /dev/null
+++ b/drivers/video/mediatek/mtk_disp_mutex_mt8188.c
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Mediatek Video Disp Mutex Support
+ *
+ * Copyright (c) 2025 BayLibre, SAS.
+ * Author: Julien Stephan <[email protected]>
+ */
+
+#include <dm.h>
+
+#include "mtk_disp_comp.h"
+#include "mtk_disp_mutex_mt8188.h"
+
+#define DISP_MUTEX1_EN         0x40
+#define DISP_MUTEX1_CTL                0x4c
+#define MUTEX_SOF_DPI1         0x5
+#define MUTEX_EOF_DPI1         (0x5 << 7)
+#define DISP_MUTEX1_MOD0       0x50
+#define DISP_MUTEX1_MOD1       0x54
+
+/*
+ * Modules attached to mutex1, bit indices as in the Linux mtk-mutex
+ * driver (MT8188_MUTEX_MOD_DISP1_*). MOD0 holds modules 0-31, MOD1
+ * holds modules 32-63.
+ */
+#define MUTEX_MOD0_MDP_RDMA4   BIT(4)
+#define MUTEX_MOD0_MDP_RDMA5   BIT(5)
+#define MUTEX_MOD0_PADDING4    BIT(12)
+#define MUTEX_MOD0_PADDING5    BIT(13)
+#define MUTEX_MOD0_VPP_MERGE2  BIT(22)
+#define MUTEX_MOD0_VPP_MERGE4  BIT(24)
+#define MUTEX_MOD0_DISP_MIXER  BIT(30)
+#define MUTEX_MOD1_DPI1                BIT(38 - 32)
+
+void mtk_disp_mutex_config(struct udevice *dev)
+{
+       /* the pipeline for the hdmi connection ends with DPI1 -> HDMI */
+       mtk_disp_comp_write(dev, DISP_MUTEX1_CTL,
+                           MUTEX_EOF_DPI1 | MUTEX_SOF_DPI1);
+
+       /* attach the modules of the DPI1 pipeline to mutex1 */
+       mtk_disp_comp_write(dev, DISP_MUTEX1_MOD0,
+                           MUTEX_MOD0_MDP_RDMA4 | MUTEX_MOD0_MDP_RDMA5 |
+                           MUTEX_MOD0_PADDING4 | MUTEX_MOD0_PADDING5 |
+                           MUTEX_MOD0_VPP_MERGE2 | MUTEX_MOD0_VPP_MERGE4 |
+                           MUTEX_MOD0_DISP_MIXER);
+       mtk_disp_comp_write(dev, DISP_MUTEX1_MOD1, MUTEX_MOD1_DPI1);
+
+       mtk_disp_comp_write(dev, DISP_MUTEX1_EN, 0x1);
+}
+
+static const struct udevice_id mtk_disp_mutex_ids[] = {
+       { .compatible = "mediatek,mt8188-disp-mutex" },
+       {}
+};
+
+U_BOOT_DRIVER(mtk_disp_mutex) = {
+       .name      = "mtk_disp_mutex",
+       .id        = UCLASS_MISC,
+       .of_match  = mtk_disp_mutex_ids,
+       .probe     = mtk_disp_comp_probe,
+       .priv_auto = sizeof(struct mtk_disp_comp_priv),
+};
diff --git a/drivers/video/mediatek/mtk_disp_mutex_mt8188.h 
b/drivers/video/mediatek/mtk_disp_mutex_mt8188.h
new file mode 100644
index 00000000000..1739c0e2381
--- /dev/null
+++ b/drivers/video/mediatek/mtk_disp_mutex_mt8188.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2025 BayLibre, SAS.
+ * Author: Julien Stephan <[email protected]>
+ */
+
+#ifndef _MTK_DISP_MUTEX_MT8188_H
+#define _MTK_DISP_MUTEX_MT8188_H
+
+struct udevice;
+
+void mtk_disp_mutex_config(struct udevice *dev);
+
+#endif

-- 
2.54.0

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