[PATCH v8 10/16] drm/mediatek: Support "None" blending in Mixer

[Shawn Sung <shawn.sung@xxxxxxxxxxxx>]

From: Hsiao Chien Sung <shawn.sung@xxxxxxxxxxxx>

Support "None" alpha blending mode on MediaTek's chips.

Signed-off-by: Hsiao Chien Sung <shawn.sung@xxxxxxxxxxxx>
---
 drivers/gpu/drm/mediatek/mtk_ethdr.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_ethdr.c b/drivers/gpu/drm/mediatek/mtk_ethdr.c
index 4ffd0a064861..bcced62e455d 100644
--- a/drivers/gpu/drm/mediatek/mtk_ethdr.c
+++ b/drivers/gpu/drm/mediatek/mtk_ethdr.c
@@ -3,6 +3,7 @@
  * Copyright (c) 2021 MediaTek Inc.
  */

+#include <drm/drm_blend.h>
 #include <drm/drm_fourcc.h>
 #include <drm/drm_framebuffer.h>
 #include <linux/clk.h>
@@ -154,6 +155,7 @@ 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);

@@ -173,8 +175,16 @@ 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,
-				  DEFAULT_9BIT_ALPHA,
+	if (state->base.pixel_blend_mode == DRM_MODE_BLEND_PIXEL_NONE ||
+	    (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