linux-kernel - [PATCH v2 14/14] drm/mediatek: Fix XRGB setting error in OVL

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Message-Id: <20240619-mediatek-drm-next-v2-14-abf68f46f8d2@mediatek.com>
Date: Wed, 19 Jun 2024 22:30:55 +0800
From: Hsiao Chien Sung via B4 Relay <devnull+shawn.sung.mediatek.com@...nel.org>
To: Chun-Kuang Hu <chunkuang.hu@...nel.org>, 
 Philipp Zabel <p.zabel@...gutronix.de>, David Airlie <airlied@...il.com>, 
 Daniel Vetter <daniel@...ll.ch>, Matthias Brugger <matthias.bgg@...il.com>, 
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
 CK Hu <ck.hu@...iatek.com>, Bibby Hsieh <bibby.hsieh@...iatek.com>, 
 Daniel Kurtz <djkurtz@...omium.org>, YT Shen <yt.shen@...iatek.com>, 
 Mao Huang <littlecvr@...omium.org>, "Nancy.Lin" <nancy.lin@...iatek.com>
Cc: dri-devel@...ts.freedesktop.org, linux-mediatek@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 Hsiao Chien Sung <shawn.sung@...iatek.com>
Subject: [PATCH v2 14/14] drm/mediatek: Fix XRGB setting error in OVL

From: Hsiao Chien Sung <shawn.sung@...iatek.com>

CONST_BLD must be enabled for XRGB formats although the alpha channel
can be ignored, or OVL will still read the value from memory.
This error only affects CRC generation.

Fixes: 119f5173628a ("drm/mediatek: Add DRM Driver for Mediatek SoC MT8173.")
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_disp_ovl.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
index f358dbfed5e3..6abefc338045 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
@@ -455,6 +455,14 @@ void mtk_ovl_layer_config(struct device *dev, unsigned int idx,
 		con |= state->base.alpha & OVL_CON_ALPHA;
 	}
 
+	/* CONST_BLD must be enabled for XRGB formats although the alpha channel
+	 * can be ignored, or OVL will still read the value from memory.
+	 * For RGB888 related formats, whether CONST_BLD is enabled or not won't
+	 * affect the result. Therefore we use !has_alpha as the condition.
+	 */
+	if (state->base.fb && !state->base.fb->format->has_alpha)
+		ignore_pixel_alpha = OVL_CONST_BLEND;
+
 	/* CONST_BLD must be enabled for XRGB formats although the alpha channel
 	 * can be ignored, or OVL will still read the value from memory.
 	 * For RGB888 related formats, whether CONST_BLD is enabled or not won't

-- 
Git-146)