lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Fri, 22 Mar 2024 13:28:22 +0800
From: Shawn Sung <shawn.sung@...iatek.com>
To: Chun-Kuang Hu <chunkuang.hu@...nel.org>, AngeloGioacchino Del Regno
	<angelogioacchino.delregno@...labora.com>
CC: Philipp Zabel <p.zabel@...gutronix.de>, David Airlie <airlied@...il.com>,
	Daniel Vetter <daniel@...ll.ch>, Matthias Brugger <matthias.bgg@...il.com>,
	Bibby Hsieh <bibby.hsieh@...iatek.com>, CK Hu <ck.hu@...iatek.com>, "Nancy .
 Lin" <nancy.lin@...iatek.com>, Fei Shao <fshao@...omium.org>, Sean Paul
	<sean@...rly.run>, Jason Chen
	<jason-ch.chen@...iatek.corp-partner.google.com>,
	<dri-devel@...ts.freedesktop.org>, <linux-mediatek@...ts.infradead.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
	"Hsiao Chien Sung" <shawn.sung@...iatek.com>
Subject: [PATCH v6 07/14] drm/mediatek: Support alpha blending in display driver

From: Hsiao Chien Sung <shawn.sung@...iatek.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@...labora.com>
Reviewed-by: CK Hu <ck.hu@...iatek.com>
Signed-off-by: Hsiao Chien Sung <shawn.sung@...iatek.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_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;
-- 
2.18.0


Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ