<html><body><p> <pre> Hi, Shawn: On Fri, 2024-03-22 at 13:28 +0800, Shawn Sung wrote: > From: Hsiao Chien Sung <shawn.sung@mediatek.com> > > 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. > > Reviewed-by: AngeloGioacchino Del Regno < > angelogioacchino.delregno@collabora.com> > Reviewed-by: CK Hu <ck.hu@mediatek.com> > Signed-off-by: Hsiao Chien Sung <shawn.sung@mediatek.com> > --- > drivers/gpu/drm/mediatek/mtk_plane.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/drivers/gpu/drm/mediatek/mtk_plane.c > b/drivers/gpu/drm/mediatek/mtk_plane.c > index 1723d4333f371..5bf757a3ef202 100644 > --- a/drivers/gpu/drm/mediatek/mtk_plane.c > +++ b/drivers/gpu/drm/mediatek/mtk_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_P > REMULTI) | > + BIT(DRM_MODE_BLEND_C > OVERAGE) | > + BIT(DRM_MODE_BLEND_P > IXEL_NONE)); After all sub driver support these function, then create blend property. So move this patch after all sub driver support these blend mode. Regards, CK > +if (err) > +DRM_ERROR("failed to create property: blend_mode\n"); > + > drm_plane_helper_add(plane, &mtk_plane_helper_funcs); > > return 0; </pre> </p></body></html><pre>************* MEDIATEK Confidentiality Notice ******************** The information contained in this e-mail message (including any attachments) may be confidential, proprietary, privileged, or otherwise exempt from disclosure under applicable laws. It is intended to be conveyed only to the designated recipient(s). Any use, dissemination, distribution, printing, retaining or copying of this e-mail (including its attachments) by unintended recipient(s) is strictly prohibited and may be unlawful. If you are not an intended recipient of this e-mail, or believe that you have received this e-mail in error, please notify the sender immediately (by replying to this e-mail), delete any and all copies of this e-mail (including any attachments) from your system, and do not disclose the content of this e-mail to any other person. Thank you! </pre>