[PATCH v9 10/21] drm/mediatek: Fix XRGB setting error in Mixer

[Shawn Sung <shawn.sung@mediatek.com>]

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

Although the alpha channel in XRGB formats can be ignored, ALPHA_CON
must be configured accordingly when using XRGB formats or it will still
affects CRC generation.

Fixes: d886c0009bd0 ("drm/mediatek: Add ETHDR support for MT8195")
Signed-off-by: Hsiao Chien Sung <shawn.sung@mediatek.com>
---
 drivers/gpu/drm/mediatek/mtk_ethdr.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_ethdr.c b/drivers/gpu/drm/mediatek/mtk_ethdr.c
index 9796fd1d51f2..902dec03a7dd 100644
--- a/drivers/gpu/drm/mediatek/mtk_ethdr.c
+++ b/drivers/gpu/drm/mediatek/mtk_ethdr.c
@@ -153,6 +153,7 @@ void mtk_ethdr_layer_config(struct device *dev, unsigned int idx,
 	unsigned int offset = (pending->x & 1) << 31 | pending->y << 16 | pending->x;
 	unsigned int align_width = ALIGN_DOWN(pending->width, 2);
 	unsigned int alpha_con = 0;
+	bool replace_src_a = false;
 
 	dev_dbg(dev, "%s+ idx:%d", __func__, idx);
 
@@ -172,8 +173,15 @@ void mtk_ethdr_layer_config(struct device *dev, unsigned int idx,
 	if (state->base.fb && state->base.fb->format->has_alpha)
 		alpha_con = MIXER_ALPHA_AEN | MIXER_ALPHA;
 
-	mtk_mmsys_mixer_in_config(priv->mmsys_dev, idx + 1, alpha_con ? false : true,
-				  MIXER_ALPHA,
+	if (state->base.fb && !state->base.fb->format->has_alpha) {
+		/*
+		 * Mixer doesn't support CONST_BLD mode,
+		 * use a trick to make the output equivalent
+		 */
+		replace_src_a = true;
+	}
+
+	mtk_mmsys_mixer_in_config(priv->mmsys_dev, idx + 1, replace_src_a, MIXER_ALPHA,
 				  pending->x & 1 ? MIXER_INX_MODE_EVEN_EXTEND :
 				  MIXER_INX_MODE_BYPASS, align_width / 2 - 1, cmdq_pkt);
 
-- 
2.18.0