| Message ID | 20240215101119.12629-8-shawn.sung@mediatek.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Support IGT in display driver | expand |
Il 15/02/24 11:11, Hsiao Chien Sung ha scritto: > Support "Pre-multiplied" and "None" blend mode on MediaTek's chips by > adding correct blend mode property when the planes init. > Before this patch, only the "Coverage" mode (default) is supported. > > For more information, there are three pixel blend modes in DRM driver: > "None", "Pre-multiplied", and "Coverage". > > To understand the difference between these modes, let's take a look at > the following two approaches to do alpha blending: > > 1. Straight: > dst.RGB = src.RGB * src.A + dst.RGB * (1 - src.A) > This is straightforward and easy to understand, when the source layer is > compositing with the destination layer, it's alpha will affect the > result. This is also known as "post-multiplied", or "Coverage" mode. > > 2. Pre-multiplied: > dst.RGB = src.RGB + dst.RGB * (1 - src.A) > Since the source RGB have already multiplied its alpha, only destination > RGB need to multiply it. This is the "Pre-multiplied" mode in DRM. > > For the "None" blend mode in DRM, it means the pixel alpha is ignored > when compositing the layers, only the constant alpha for the composited > layer will take effects. > > Signed-off-by: Hsiao Chien Sung <shawn.sung@mediatek.com> > Reviewed-by: CK Hu <ck.hu@mediatek.com> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
diff --git a/drivers/gpu/drm/mediatek/mtk_drm_plane.c b/drivers/gpu/drm/mediatek/mtk_drm_plane.c index 2dc28a79f7603..4e0206c45efd7 100644 --- a/drivers/gpu/drm/mediatek/mtk_drm_plane.c +++ b/drivers/gpu/drm/mediatek/mtk_drm_plane.c @@ -346,6 +346,17 @@ 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, + BIT(DRM_MODE_BLEND_PREMULTI) | + BIT(DRM_MODE_BLEND_COVERAGE) | + BIT(DRM_MODE_BLEND_PIXEL_NONE)); + if (err) + DRM_ERROR("failed to create property: blend_mode\n"); + drm_plane_helper_add(plane, &mtk_plane_helper_funcs); return 0;