Re: [PATCH v2 06/11] drm/mediatek: Support alpha blending in display driver

[CK Hu (胡俊光)]

Hi, Hsiao-chien:

On Mon, 2023-09-18 at 16:42 +0800, Hsiao Chien Sung wrote:
> Support alpha blending by adding correct blend mode and
> alpha property in plane initialization.
> 
> Reviewed-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@xxxxxxxxxxxxx>
> Signed-off-by: Hsiao Chien Sung <shawn.sung@xxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/mediatek/mtk_drm_plane.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_plane.c
> b/drivers/gpu/drm/mediatek/mtk_drm_plane.c
> index db2f70ae060d..f87cf56fb846 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_plane.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_plane.c
> @@ -301,6 +301,9 @@ int mtk_plane_init(struct drm_device *dev, struct
> drm_plane *plane,
>  		   size_t num_formats)
>  {
>  	int err;
> +	u32 blend_mode = BIT(DRM_MODE_BLEND_PIXEL_NONE) |
> +			 BIT(DRM_MODE_BLEND_PREMULTI)   |
> +			 BIT(DRM_MODE_BLEND_COVERAGE);
>  
>  	if (!formats || !num_formats) {
>  		DRM_ERROR("no formats for plane\n");
> @@ -323,6 +326,14 @@ int mtk_plane_init(struct drm_device *dev,
> struct drm_plane *plane,
>  			DRM_INFO("Create rotation property failed\n");
>  	}
>  
> +	err = drm_plane_create_alpha_property(plane);
> +	if (err)
> +		DRM_ERROR("failed to create property: alpha\n");
> +
> +	err = drm_plane_create_blend_mode_property(plane, blend_mode);
> +	if (err)
> +		DRM_ERROR("failed to create property: blend_mode\n");

Do not always enable alpha function. Enable it depend on hardware
capability.

Regards,
CK

> +
>  	drm_plane_helper_add(plane, &mtk_plane_helper_funcs);
>  
>  	return 0;