Re: [PATCH v2 04/14] video: mediatek: add mutex component

On 8/26/26 8:09 AM, Julien Stephan wrote:
> 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.c | 63 +++++++++++++++++++++++++++++++++
>  drivers/video/mediatek/mtk_disp_mutex.h | 14 ++++++++
>  2 files changed, 77 insertions(+)
> 
> diff --git a/drivers/video/mediatek/mtk_disp_mutex.c b/drivers/video/mediatek/mtk_disp_mutex.c
> new file mode 100644
> index 00000000000..8619d9491a2
> --- /dev/null
> +++ b/drivers/video/mediatek/mtk_disp_mutex.c
> @@ -0,0 +1,63 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Mediatek Video Disp Mutex Support
> + *
> + * Copyright (c) 2026 BayLibre, SAS.
> + * Author: Julien Stephan <[email protected]>
> + */
> +
> +#include <dm.h>
> +
> +#include "mtk_disp_comp.h"
> +#include "mtk_disp_mutex.h"
> +
> +#define DISP_MUTEX1_EN		0x40
> +#define DISP_MUTEX1_CTL		0x4c

This currently hard-codes use of mutex1, but DSI will also use this driver
with mutex0. Might as well make it support both now to avoid churn later.

> +#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.h b/drivers/video/mediatek/mtk_disp_mutex.h
> new file mode 100644
> index 00000000000..cbf8a9f0537
> --- /dev/null
> +++ b/drivers/video/mediatek/mtk_disp_mutex.h
> @@ -0,0 +1,14 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2026 BayLibre, SAS.
> + * Author: Julien Stephan <[email protected]>
> + */
> +
> +#ifndef _MTK_DISP_MUTEX_H
> +#define _MTK_DISP_MUTEX_H
> +
> +struct udevice;
> +
> +void mtk_disp_mutex_config(struct udevice *dev);
> +
> +#endif
>