Re: [PATCH v6 11/11] drm/mediatek: Add Write DMA (WDMA) Engine for Writeback support

[CK Hu (胡俊光)]

On Wed, 2026-07-15 at 15:57 +0200, AngeloGioacchino Del Regno wrote:
> Add a basic driver for the Write DMA Engine and initial compatible
> for the MediaTek MT8173 and MediaTek Dimensity 1200 MT6893, and
> hook it up to the mtk_ddp_comp and mtk_drm_drv in order for it to
> probe.
> 
> This display controller component is used to enable the writeback
> engine that can be used for faster display image capturing in the
> userspace (for example, screenshots and screen recording).
> 
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
> ---
>  
> +static const struct mtk_ddp_comp_funcs ddp_wdma = {
> +	.clk_enable = mtk_wdma_clk_enable,
> +	.clk_disable = mtk_wdma_clk_disable,
> +	.config = mtk_wdma_config,
> +	.start = mtk_wdma_start,
> +	.stop = mtk_wdma_stop,
> +	.register_vblank_cb = mtk_wdma_register_vblank_cb,
> +	.unregister_vblank_cb = mtk_wdma_unregister_vblank_cb,
> +	.enable_vblank = mtk_wdma_enable_vblank,
> +	.disable_vblank = mtk_wdma_disable_vblank,
> +	.layer_nr = mtk_wdma_layer_nr,
> +	.layer_config = mtk_wdma_layer_config,
> +	.get_formats = mtk_wdma_get_formats,
> +	.get_num_formats = mtk_wdma_get_num_formats,

I does not see you modify mtk crtc.
mtk crtc would use some interface only on 'first' ddp component of a pipeline.
WDMA would not be the first component,
so register_vblank_cb, unregister_vblank_cb, enable_vblank, disable_vblank, layer_nr, layer_config, get_formats, and get_num_formats are useless.

Regards,
CK

> +};
> +