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

[Hsiao Chien Sung via B4 Relay]

From: Hsiao Chien Sung <shawn.sung at mediatek.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 at collabora.com>
Reviewed-by: CK Hu <ck.hu at mediatek.com>
Signed-off-by: Hsiao Chien Sung <shawn.sung at mediatek.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)