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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Miles Chen <miles.chen@mediatek.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Zhiqiang Lin <zhiqiang.lin@mediatek.com>,
        CK Hu <ck.hu@mediatek.com>,
        Chun-Kuang Hu <chunkuang.hu@kernel.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 131/452] drm/mediatek: Fix mtk_cec_mask()
Date:   Tue,  7 Jun 2022 18:59:48 +0200
Message-Id: <20220607164912.462816952@linuxfoundation.org>
In-Reply-To: <20220607164908.521895282@linuxfoundation.org>
References: <20220607164908.521895282@linuxfoundation.org>
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From: Miles Chen <miles.chen@mediatek.com>

[ Upstream commit 2c5d69b0a141e1e98febe3111e6f4fd8420493a5 ]

In current implementation, mtk_cec_mask() writes val into target register
and ignores the mask. After talking to our hdmi experts, mtk_cec_mask()
should read a register, clean only mask bits, and update (val | mask) bits
to the register.

Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20220315232301.2434-1-miles.chen@mediatek.com/
Fixes: 8f83f26891e1 ("drm/mediatek: Add HDMI support")
Signed-off-by: Miles Chen <miles.chen@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Zhiqiang Lin <zhiqiang.lin@mediatek.com>
Cc: CK Hu <ck.hu@mediatek.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/mediatek/mtk_cec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_cec.c b/drivers/gpu/drm/mediatek/mtk_cec.c
index cb29b649fcdb..12bf93769497 100644
--- a/drivers/gpu/drm/mediatek/mtk_cec.c
+++ b/drivers/gpu/drm/mediatek/mtk_cec.c
@@ -84,7 +84,7 @@ static void mtk_cec_mask(struct mtk_cec *cec, unsigned int offset,
 	u32 tmp = readl(cec->regs + offset) & ~mask;
 
 	tmp |= val & mask;
-	writel(val, cec->regs + offset);
+	writel(tmp, cec->regs + offset);
 }
 
 void mtk_cec_set_hpd_event(struct device *dev,
-- 
2.35.1