[PATCH v11 7/9] drm/mediatek: enable dither function

[Hsin-Yi Wang]

From: Yongqiang Niu <yongqiang....@mediatek.com>

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

Signed-off-by: Yongqiang Niu <yongqiang....@mediatek.com>
Signed-off-by: Hsin-Yi Wang <hsi...@chromium.org>
---
 drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c | 44 ++++++++++++++++++++-
 1 file changed, 43 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 8173f709272be..e85625704d611 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
 
@@ -313,8 +315,48 @@ static void mtk_dither_config(struct device *dev, unsigned 
int w,
 {
        struct mtk_ddp_comp_dev *priv = dev_get_drvdata(dev);
 
+       bool enable = false;
+
+       /* default value for dither reg 5 to 14 */
+       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 == 5 || bpc == 6) {
+               enable = true;
+               mtk_ddp_write(cmdq_pkt,
+                             DITHER_LSB_ERR_SHIFT_R(MTK_MAX_BPC - bpc) |
+                             DITHER_ADD_LSHIFT_R(MTK_MAX_BPC - bpc) |
+                             DITHER_NEW_BIT_MODE,
+                             &priv->cmdq_reg, priv->regs, DITHER_REG(15));
+               mtk_ddp_write(cmdq_pkt,
+                             DITHER_LSB_ERR_SHIFT_B(MTK_MAX_BPC - bpc) |
+                             DITHER_ADD_LSHIFT_B(MTK_MAX_BPC - bpc) |
+                             DITHER_LSB_ERR_SHIFT_G(MTK_MAX_BPC - bpc) |
+                             DITHER_ADD_LSHIFT_G(MTK_MAX_BPC - bpc),
+                             &priv->cmdq_reg, priv->regs, DITHER_REG(16));
+       }
+
+
+       if (enable) {
+               u32 idx;
+
+               for (idx = 0; idx < ARRAY_SIZE(dither_setting); idx++)
+                       mtk_ddp_write(cmdq_pkt, dither_setting[idx], 
&priv->cmdq_reg, priv->regs,
+                                     DITHER_REG(idx + 5));
+       }
+
        mtk_ddp_write(cmdq_pkt, h << 16 | w, &priv->cmdq_reg, priv->regs, 
DISP_DITHER_SIZE);
-       mtk_ddp_write(cmdq_pkt, DITHER_RELAY_MODE, &priv->cmdq_reg, priv->regs, 
DISP_DITHER_CFG);
+        mtk_ddp_write(cmdq_pkt, enable ? DITHER_ENGINE_EN : DITHER_RELAY_MODE, 
&priv->cmdq_reg, priv->regs, DISP_DITHER_CFG);
 }
 
 static void mtk_dither_start(struct device *dev)
-- 
2.30.0.280.ga3ce27912f-goog