[PATCH v9, 09/11] drm/mediatek: enable dither function

[Yongqiang Niu <yongqiang.niu@xxxxxxxxxxxx>]

for 5 or 6 bpc panel, we need enable dither function
to improve the display quality

Signed-off-by: Yongqiang Niu <yongqiang.niu@xxxxxxxxxxxx>
---
 drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c | 38 ++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
index 03589c9..81ed076 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
@@ -53,7 +53,9 @@
 #define DITHER_EN				BIT(0)
 #define DISP_DITHER_CFG				0x0020
 #define DITHER_RELAY_MODE			BIT(0)
+#define DITHER_ENGINE_EN			BIT(1)
 #define DISP_DITHER_SIZE			0x0030
+#define DITHER_REG(idx)				(0x100 + (idx) * 4)
 
 #define LUT_10BIT_MASK				0x03ff
 
@@ -258,8 +260,42 @@ static void mtk_dither_config(struct mtk_ddp_comp *comp, unsigned int w,
 			      unsigned int h, unsigned int vrefresh,
 			      unsigned int bpc, struct cmdq_pkt *cmdq_pkt)
 {
+	bool enable = true;
+
+	const u32 dither_setting[] = {
+		0x00000000, /* 5 */
+		0x00003002, /* 6 */
+		0x00000000, /* 7 */
+		0x00000000, /* 8 */
+		0x00000000, /* 9 */
+		0x00000000, /* 10 */
+		0x00000000, /* 11 */
+		0x00000011, /* 12 */
+		0x00000000, /* 13 */
+		0x00000000, /* 14 */
+	};
+
+	if (bpc == 6) {
+		mtk_ddp_write(cmdq_pkt, 0x40400001, comp, DITHER_REG(15));
+		mtk_ddp_write(cmdq_pkt, 0x40404040, comp, DITHER_REG(16));
+	} else if (bpc == 5) {
+		mtk_ddp_write(cmdq_pkt, 0x50500001, comp, DITHER_REG(15));
+		mtk_ddp_write(cmdq_pkt, 0x50504040, comp, DITHER_REG(16));
+	} else {
+		enable = false;
+	}
+
+	if (enable) {
+		u32 idx;
+
+		for (idx = 0; idx < ARRAY_SIZE(dither_setting); idx++)
+			mtk_ddp_write(cmdq_pkt, dither_setting[idx], comp,
+				      DITHER_REG(idx + 5));
+	}
+
 	mtk_ddp_write(cmdq_pkt, h << 16 | w, comp, DISP_DITHER_SIZE);
-	mtk_ddp_write(cmdq_pkt, DITHER_RELAY_MODE, comp, DISP_DITHER_CFG);
+	mtk_ddp_write(cmdq_pkt, enable ? DITHER_ENGINE_EN : DITHER_RELAY_MODE,
+		      comp, DISP_DITHER_CFG);
 }
 
 static void mtk_dither_start(struct mtk_ddp_comp *comp)
-- 
1.8.1.1.dirty