linux-kernel - [PATCH 2/7] drm/mediatek: fix CCORR mtk_ctm_s31_32_to_s1

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Message-ID: <20250219092040.11227-3-jay.liu@mediatek.com>
Date: Wed, 19 Feb 2025 17:20:35 +0800
From: Jay Liu <jay.liu@...iatek.com>
To: Chun-Kuang Hu <chunkuang.hu@...nel.org>, Philipp Zabel
	<p.zabel@...gutronix.de>, Maarten Lankhorst
	<maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>, Rob Herring <robh@...nel.org>, Krzysztof
 Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Matthias
 Brugger <matthias.bgg@...il.com>, AngeloGioacchino Del Regno
	<angelogioacchino.delregno@...labora.com>, Yongqiang Niu
	<yongqiang.niu@...iatek.com>, CK Hu <ck.hu@...iatek.com>, Hsin-Yi Wang
	<hsinyi@...omium.org>
CC: <dri-devel@...ts.freedesktop.org>, <linux-mediatek@...ts.infradead.org>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<Project_Global_Chrome_Upstream_Group@...iatek.com>, Jay Liu
	<jay.liu@...iatek.com>
Subject: [PATCH 2/7] drm/mediatek: fix CCORR mtk_ctm_s31_32_to_s1_n function issue

if matrixbit is 11,
The range of color matrix is from 0 to (BIT(11) - 1).
Values from 0 to (BIT(11) - 1) represent positive numbers,
values from BIT(11) to (BIT(12) - 1) represent negative numbers.
For example, -1 need converted to 8191.

Fixes: 738ed4156fba ("drm/mediatek: Add matrix_bits private data for ccorr")

Signed-off-by: Jay Liu <jay.liu@...iatek.com>
---
 drivers/gpu/drm/mediatek/mtk_disp_ccorr.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ccorr.c b/drivers/gpu/drm/mediatek/mtk_disp_ccorr.c
index 94e82b3fa2d8..a9f91b71534b 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_ccorr.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_ccorr.c
@@ -100,6 +100,15 @@ static u16 mtk_ctm_s31_32_to_s1_n(u64 in, u32 n)
 		r |= (in >> (32 - n)) & GENMASK(n, 0);
 	}
 
+	/*
+	 *The range of r is from 0 to (BIT(n + 1) - 1),
+	 *where values from 0 to (BIT(n) - 1) represent positive numbers,
+	 *and values from BIT(n) to (BIT(n + 1) - 1) represent negative numbers.
+	 *For example, if n is 11, -1 will be converted to 8191.
+	 */
+	if (r & BIT(n + 1))
+		r = (~(r & GENMASK(n, 0)) + 1) & GENMASK(n + 1, 0);
+
 	return r;
 }
 
-- 
2.18.0