[PATCH v8 11/16] drm/mediatek: Support "Pre-multiplied" blending in OVL

[Shawn Sung]

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

Support "Pre-multiplied" alpha blending mode on in OVL.
Before this patch, only the "coverage" mode is supported.

Signed-off-by: Hsiao Chien Sung <shawn.sung@xxxxxxxxxxxx>
---
 drivers/gpu/drm/mediatek/mtk_disp_ovl.c | 40 +++++++++++++++++++++----
 1 file changed, 34 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
index 54a6f11aa867..de1633988921 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
@@ -52,13 +52,16 @@
 #define GMC_THRESHOLD_HIGH	((1 << GMC_THRESHOLD_BITS) / 4)
 #define GMC_THRESHOLD_LOW	((1 << GMC_THRESHOLD_BITS) / 8)
 
+#define OVL_CON_CLRFMT_MAN	BIT(23)
 #define OVL_CON_BYTE_SWAP	BIT(24)
-#define OVL_CON_MTX_YUV_TO_RGB	(6 << 16)
+#define OVL_CON_RGB_SWAP	BIT(25)
 #define OVL_CON_CLRFMT_RGB	(1 << 12)
 #define OVL_CON_CLRFMT_RGBA8888	(2 << 12)
 #define OVL_CON_CLRFMT_ARGB8888	(3 << 12)
 #define OVL_CON_CLRFMT_UYVY	(4 << 12)
 #define OVL_CON_CLRFMT_YUYV	(5 << 12)
+#define OVL_CON_MTX_YUV_TO_RGB	(6 << 16)
+#define OVL_CON_CLRFMT_PARGB8888	(OVL_CON_CLRFMT_ARGB8888 | OVL_CON_CLRFMT_MAN)
 #define OVL_CON_CLRFMT_RGB565(ovl)	((ovl)->data->fmt_rgb565_is_0 ? \
 					0 : OVL_CON_CLRFMT_RGB)
 #define OVL_CON_CLRFMT_RGB888(ovl)	((ovl)->data->fmt_rgb565_is_0 ? \
@@ -72,6 +75,8 @@
 #define	OVL_CON_VIRT_FLIP	BIT(9)
 #define	OVL_CON_HORZ_FLIP	BIT(10)
 
+#define OVL_COLOR_ALPHA		GENMASK(31, 24)
+
 static inline bool is_10bit_rgb(u32 fmt)
 {
 	switch (fmt) {
@@ -296,7 +301,13 @@ void mtk_ovl_config(struct device *dev, unsigned int w,
 	if (w != 0 && h != 0)
 		mtk_ddp_write_relaxed(cmdq_pkt, h << 16 | w, &ovl->cmdq_reg, ovl->regs,
 				      DISP_REG_OVL_ROI_SIZE);
-	mtk_ddp_write_relaxed(cmdq_pkt, 0x0, &ovl->cmdq_reg, ovl->regs, DISP_REG_OVL_ROI_BGCLR);
+
+	/*
+	 * The background color must be opaque black (ARGB),
+	 * otherwise the alpha blending will have no effect
+	 */
+	mtk_ddp_write_relaxed(cmdq_pkt, OVL_COLOR_ALPHA, &ovl->cmdq_reg,
+			      ovl->regs, DISP_REG_OVL_ROI_BGCLR);
 
 	mtk_ddp_write(cmdq_pkt, 0x1, &ovl->cmdq_reg, ovl->regs, DISP_REG_OVL_RST);
 	mtk_ddp_write(cmdq_pkt, 0x0, &ovl->cmdq_reg, ovl->regs, DISP_REG_OVL_RST);
@@ -372,7 +383,8 @@ void mtk_ovl_layer_off(struct device *dev, unsigned int idx,
 		      DISP_REG_OVL_RDMA_CTRL(idx));
 }
 
-static unsigned int ovl_fmt_convert(struct mtk_disp_ovl *ovl, unsigned int fmt)
+static unsigned int ovl_fmt_convert(struct mtk_disp_ovl *ovl, unsigned int fmt,
+				    unsigned int blend_mode)
 {
 	/* The return value in switch "MEM_MODE_INPUT_FORMAT_XXX"
 	 * is defined in mediatek HW data sheet.
@@ -391,21 +403,35 @@ static unsigned int ovl_fmt_convert(struct mtk_disp_ovl *ovl, unsigned int fmt)
 		return OVL_CON_CLRFMT_RGB888(ovl) | OVL_CON_BYTE_SWAP;
 	case DRM_FORMAT_RGBX8888:
 	case DRM_FORMAT_RGBA8888:
+		return blend_mode == DRM_MODE_BLEND_COVERAGE ?
+		       OVL_CON_CLRFMT_ARGB8888 :
+		       OVL_CON_CLRFMT_PARGB8888;
 	case DRM_FORMAT_RGBX1010102:
 	case DRM_FORMAT_RGBA1010102:
 		return OVL_CON_CLRFMT_ARGB8888;
 	case DRM_FORMAT_BGRX8888:
 	case DRM_FORMAT_BGRA8888:
+		return OVL_CON_BYTE_SWAP |
+		       (blend_mode == DRM_MODE_BLEND_COVERAGE ?
+		       OVL_CON_CLRFMT_ARGB8888 :
+		       OVL_CON_CLRFMT_PARGB8888);
 	case DRM_FORMAT_BGRX1010102:
 	case DRM_FORMAT_BGRA1010102:
 		return OVL_CON_CLRFMT_ARGB8888 | OVL_CON_BYTE_SWAP;
 	case DRM_FORMAT_XRGB8888:
 	case DRM_FORMAT_ARGB8888:
+		return blend_mode == DRM_MODE_BLEND_COVERAGE ?
+		       OVL_CON_CLRFMT_RGBA8888 :
+		       OVL_CON_CLRFMT_PARGB8888;
 	case DRM_FORMAT_XRGB2101010:
 	case DRM_FORMAT_ARGB2101010:
 		return OVL_CON_CLRFMT_RGBA8888;
 	case DRM_FORMAT_XBGR8888:
 	case DRM_FORMAT_ABGR8888:
+		return OVL_CON_RGB_SWAP |
+		       (blend_mode == DRM_MODE_BLEND_COVERAGE ?
+		       OVL_CON_CLRFMT_RGBA8888 :
+		       OVL_CON_CLRFMT_PARGB8888);
 	case DRM_FORMAT_XBGR2101010:
 	case DRM_FORMAT_ABGR2101010:
 		return OVL_CON_CLRFMT_RGBA8888 | OVL_CON_BYTE_SWAP;
@@ -448,9 +474,11 @@ void mtk_ovl_layer_config(struct device *dev, unsigned int idx,
 		return;
 	}
 
-	con = ovl_fmt_convert(ovl, fmt);
-	if (state->base.fb && state->base.fb->format->has_alpha)
-		con |= OVL_CON_AEN | OVL_CON_ALPHA;
+	con = ovl_fmt_convert(ovl, fmt, blend_mode);
+	if (state->base.fb) {
+		con |= OVL_CON_AEN;
+		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.
-- 
2.18.0