drm/sun4i: Set blending mode for all channels (DE2)

BSP driver always sets blend mode for all channels, no matter if they
are really used or not. Do the same here.

The exact meaning of the value is not exactly known, but BSP driver
mentions "SRC OVER" and by digging through code some more info can be
found.
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171201060550.10392-8-jernej.skrabec@siol.net

drivers/gpu/drm/sun4i/sun8i_mixer.c

@@ -239,6 +239,7 @@ static int sun8i_mixer_bind(struct device *dev, struct device *master,
 	struct sun8i_mixer *mixer;
 	struct resource *res;
 	void __iomem *regs;
+	int plane_cnt;
 	int i, ret;
 
 	/*
@@ -324,8 +325,6 @@ static int sun8i_mixer_bind(struct device *dev, struct device *master,
 	/* Initialize blender */
 	regmap_write(mixer->engine.regs, SUN8I_MIXER_BLEND_FCOLOR_CTL,
 		     SUN8I_MIXER_BLEND_FCOLOR_CTL_DEF);
-	regmap_write(mixer->engine.regs, SUN8I_MIXER_BLEND_MODE(0),
-		     SUN8I_MIXER_BLEND_MODE_DEF);
 
 	regmap_write(mixer->engine.regs,
 		     SUN8I_MIXER_BLEND_ATTR_FCOLOR(0),
@@ -337,6 +336,11 @@ static int sun8i_mixer_bind(struct device *dev, struct device *master,
 	regmap_write(mixer->engine.regs, SUN8I_MIXER_BLEND_ROUTE,
 		     mixer->cfg->vi_num);
 
+	plane_cnt = mixer->cfg->vi_num + mixer->cfg->ui_num;
+	for (i = 0; i < plane_cnt; i++)
+		regmap_write(mixer->engine.regs, SUN8I_MIXER_BLEND_MODE(i),
+			     SUN8I_MIXER_BLEND_MODE_DEF);
+
 	return 0;
 
 err_disable_bus_clk: