video: stm32: stm32_ltdc: set the blending factor

Set the blending factor regarding the pixel format

Signed-off-by: yannick fertre <yannick.fertre@st.com>

drivers/video/stm32/stm32_ltdc.c

@@ -138,7 +138,9 @@ struct stm32_ltdc_priv {
 #define LXCFBLNR_CFBLN	GENMASK(10, 0)	/* Color Frame Buffer Line Number */
 
 #define BF1_PAXCA	0x600		/* Pixel Alpha x Constant Alpha */
+#define BF1_CA		0x400		/* Constant Alpha */
 #define BF2_1PAXCA	0x007		/* 1 - (Pixel Alpha x Constant Alpha) */
+#define BF2_1CA		0x005		/* 1 - Constant Alpha */
 
 enum stm32_ltdc_pix_fmt {
 	PF_ARGB8888 = 0,
@@ -161,11 +163,17 @@ static u32 stm32_ltdc_get_pixel_format(enum video_log2_bpp l2bpp)
 		pf = PF_RGB565;
 		break;
 
+	case VIDEO_BPP32:
+		pf = PF_ARGB8888;
+		break;
+
+	case VIDEO_BPP8:
+		pf = PF_L8;
+		break;
+
 	case VIDEO_BPP1:
 	case VIDEO_BPP2:
 	case VIDEO_BPP4:
-	case VIDEO_BPP8:
-	case VIDEO_BPP32:
 	default:
 		debug("%s: warning %dbpp not supported yet, %dbpp instead\n",
 		      __func__, VNBITS(l2bpp), VNBITS(VIDEO_BPP16));
@@ -178,6 +186,23 @@ static u32 stm32_ltdc_get_pixel_format(enum video_log2_bpp l2bpp)
 	return (u32)pf;
 }
 
+static bool has_alpha(u32 fmt)
+{
+	switch (fmt) {
+	case PF_ARGB8888:
+	case PF_ARGB1555:
+	case PF_ARGB4444:
+	case PF_AL44:
+	case PF_AL88:
+		return true;
+	case PF_RGB888:
+	case PF_RGB565:
+	case PF_L8:
+	default:
+		return false;
+	}
+}
+
 static void stm32_ltdc_enable(struct stm32_ltdc_priv *priv)
 {
 	/* Reload configuration immediately & enable LTDC */
@@ -247,6 +272,7 @@ static void stm32_ltdc_set_layer1(struct stm32_ltdc_priv *priv, ulong fb_addr)
 	u32 line_length;
 	u32 bus_width;
 	u32 val, tmp, bpp;
+	u32 format;
 
 	x0 = priv->crop_x;
 	x1 = priv->crop_x + priv->crop_w - 1;
@@ -277,15 +303,18 @@ static void stm32_ltdc_set_layer1(struct stm32_ltdc_priv *priv, ulong fb_addr)
 	clrsetbits_le32(regs + LTDC_L1CFBLR, LXCFBLR_CFBLL | LXCFBLR_CFBP, val);
 
 	/* Pixel format */
-	val = stm32_ltdc_get_pixel_format(priv->l2bpp);
-	clrsetbits_le32(regs + LTDC_L1PFCR, LXPFCR_PF, val);
+	format = stm32_ltdc_get_pixel_format(priv->l2bpp);
+	clrsetbits_le32(regs + LTDC_L1PFCR, LXPFCR_PF, format);
 
 	/* Constant alpha value */
 	clrsetbits_le32(regs + LTDC_L1CACR, LXCACR_CONSTA, priv->alpha);
 
+	/* Specifies the blending factors : with or without pixel alpha */
+	/* Manage hw-specific capabilities */
+	val = has_alpha(format) ? BF1_PAXCA | BF2_1PAXCA : BF1_CA | BF2_1CA;
+
 	/* Blending factors */
-	clrsetbits_le32(regs + LTDC_L1BFCR, LXBFCR_BF2 | LXBFCR_BF1,
-			BF1_PAXCA | BF2_1PAXCA);
+	clrsetbits_le32(regs + LTDC_L1BFCR, LXBFCR_BF2 | LXBFCR_BF1, val);
 
 	/* Frame buffer line number */
 	clrsetbits_le32(regs + LTDC_L1CFBLNR, LXCFBLNR_CFBLN, priv->crop_h);