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4225d5d5e7
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: CK Hu <ck.hu@mediatek.com> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> Signed-off-by: Hsiao Chien Sung <shawn.sung@mediatek.com> Link: https://patchwork.kernel.org/project/dri-devel/patch/20240717-alpha-blending-v4-5-4b1c806c0749@mediatek.com/ Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org> |
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certs | ||
crypto | ||
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drivers | ||
fs | ||
include | ||
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io_uring | ||
ipc | ||
kernel | ||
lib | ||
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usr | ||
virt | ||
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.get_maintainer.ignore | ||
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.mailmap | ||
.rustfmt.toml | ||
COPYING | ||
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Makefile | ||
README |
Linux kernel ============ There are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. Please read Documentation/admin-guide/README.rst first. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. The formatted documentation can also be read online at: https://www.kernel.org/doc/html/latest/ There are various text files in the Documentation/ subdirectory, several of them using the reStructuredText markup notation. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.