The SMI local arbiters (larbs) gate a subsystem's access to DRAM. On the MT8188 the display data path feeds through the VDO1 larbs (larb2 and larb3), whose clocks must be ungated for the HDMI pipeline to reach the framebuffer.
There is no dedicated SMI larb driver upstream, as Linux handles the larbs through its SMI/IOMMU framework. Add a minimal U-Boot driver that binds the "mediatek,mt8188-smi-larb" nodes and ungates their clocks, reusing the display pipeline component helpers for the register window and clock bulk. Signed-off-by: Julien Stephan <[email protected]> --- drivers/video/mediatek/mtk_smi_larb.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/drivers/video/mediatek/mtk_smi_larb.c b/drivers/video/mediatek/mtk_smi_larb.c new file mode 100644 index 00000000000..9e4440ce294 --- /dev/null +++ b/drivers/video/mediatek/mtk_smi_larb.c @@ -0,0 +1,30 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * MediaTek SMI local arbiter (larb) driver + * + * Copyright (c) 2026 BayLibre, SAS. + * Author: Julien Stephan <[email protected]> + */ + +#include <dm.h> + +#include "mtk_disp_comp.h" + +/* + * The SMI larbs gate a subsystem's access to DRAM. They have no dedicated + * driver upstream (the SMI/IOMMU framework handles them), so bind a minimal + * driver that just ungates their clocks, reusing the display component + * helpers for the register window and clock bulk. + */ +static const struct udevice_id mtk_smi_larb_ids[] = { + { .compatible = "mediatek,mt8188-smi-larb" }, + {} +}; + +U_BOOT_DRIVER(mtk_smi_larb) = { + .name = "mtk_smi_larb", + .id = UCLASS_MISC, + .of_match = mtk_smi_larb_ids, + .probe = mtk_disp_comp_probe, + .priv_auto = sizeof(struct mtk_disp_comp_priv), +}; -- 2.55.0
