drm/mediatek: enhance the HDMI driving current

In order to improve 4K resolution performance,
we have to enhance the HDMI driving current
when clock rate is greater than 165MHz.
Signed-off-by: Junzhi Zhao <junzhi.zhao@mediatek.com>
Signed-off-by: Bibby Hsieh <bibby.hsieh@mediatek.com>

drivers/gpu/drm/mediatek/mtk_mt8173_hdmi_phy.c

@@ -265,6 +265,9 @@ static int mtk_hdmi_pll_set_rate(struct clk_hw *hw, unsigned long rate,
 	struct mtk_hdmi_phy *hdmi_phy = to_mtk_hdmi_phy(hw);
 	unsigned int pre_div;
 	unsigned int div;
+	unsigned int pre_ibias;
+	unsigned int hdmi_ibias;
+	unsigned int imp_en;
 
 	dev_dbg(hdmi_phy->dev, "%s: %lu Hz, parent: %lu Hz\n", __func__,
 		rate, parent_rate);
@@ -298,18 +301,31 @@ static int mtk_hdmi_pll_set_rate(struct clk_hw *hw, unsigned long rate,
 			  (0x1 << PLL_BR_SHIFT),
 			  RG_HDMITX_PLL_BP | RG_HDMITX_PLL_BC |
 			  RG_HDMITX_PLL_BR);
-	mtk_hdmi_phy_clear_bits(hdmi_phy, HDMI_CON3, RG_HDMITX_PRD_IMP_EN);
+	if (rate < 165000000) {
+		mtk_hdmi_phy_clear_bits(hdmi_phy, HDMI_CON3,
+					RG_HDMITX_PRD_IMP_EN);
+		pre_ibias = 0x3;
+		imp_en = 0x0;
+		hdmi_ibias = hdmi_phy->ibias;
+	} else {
+		mtk_hdmi_phy_set_bits(hdmi_phy, HDMI_CON3,
+				      RG_HDMITX_PRD_IMP_EN);
+		pre_ibias = 0x6;
+		imp_en = 0xf;
+		hdmi_ibias = hdmi_phy->ibias_up;
+	}
 	mtk_hdmi_phy_mask(hdmi_phy, HDMI_CON4,
-			  (0x3 << PRD_IBIAS_CLK_SHIFT) |
-			  (0x3 << PRD_IBIAS_D2_SHIFT) |
-			  (0x3 << PRD_IBIAS_D1_SHIFT) |
-			  (0x3 << PRD_IBIAS_D0_SHIFT),
+			  (pre_ibias << PRD_IBIAS_CLK_SHIFT) |
+			  (pre_ibias << PRD_IBIAS_D2_SHIFT) |
+			  (pre_ibias << PRD_IBIAS_D1_SHIFT) |
+			  (pre_ibias << PRD_IBIAS_D0_SHIFT),
 			  RG_HDMITX_PRD_IBIAS_CLK |
 			  RG_HDMITX_PRD_IBIAS_D2 |
 			  RG_HDMITX_PRD_IBIAS_D1 |
 			  RG_HDMITX_PRD_IBIAS_D0);
 	mtk_hdmi_phy_mask(hdmi_phy, HDMI_CON3,
-			  (0x0 << DRV_IMP_EN_SHIFT), RG_HDMITX_DRV_IMP_EN);
+			  (imp_en << DRV_IMP_EN_SHIFT),
+			  RG_HDMITX_DRV_IMP_EN);
 	mtk_hdmi_phy_mask(hdmi_phy, HDMI_CON6,
 			  (hdmi_phy->drv_imp_clk << DRV_IMP_CLK_SHIFT) |
 			  (hdmi_phy->drv_imp_d2 << DRV_IMP_D2_SHIFT) |
@@ -318,12 +334,14 @@ static int mtk_hdmi_pll_set_rate(struct clk_hw *hw, unsigned long rate,
 			  RG_HDMITX_DRV_IMP_CLK | RG_HDMITX_DRV_IMP_D2 |
 			  RG_HDMITX_DRV_IMP_D1 | RG_HDMITX_DRV_IMP_D0);
 	mtk_hdmi_phy_mask(hdmi_phy, HDMI_CON5,
-			  (hdmi_phy->ibias << DRV_IBIAS_CLK_SHIFT) |
-			  (hdmi_phy->ibias << DRV_IBIAS_D2_SHIFT) |
-			  (hdmi_phy->ibias << DRV_IBIAS_D1_SHIFT) |
-			  (hdmi_phy->ibias << DRV_IBIAS_D0_SHIFT),
-			  RG_HDMITX_DRV_IBIAS_CLK | RG_HDMITX_DRV_IBIAS_D2 |
-			  RG_HDMITX_DRV_IBIAS_D1 | RG_HDMITX_DRV_IBIAS_D0);
+			  (hdmi_ibias << DRV_IBIAS_CLK_SHIFT) |
+			  (hdmi_ibias << DRV_IBIAS_D2_SHIFT) |
+			  (hdmi_ibias << DRV_IBIAS_D1_SHIFT) |
+			  (hdmi_ibias << DRV_IBIAS_D0_SHIFT),
+			  RG_HDMITX_DRV_IBIAS_CLK |
+			  RG_HDMITX_DRV_IBIAS_D2 |
+			  RG_HDMITX_DRV_IBIAS_D1 |
+			  RG_HDMITX_DRV_IBIAS_D0);
 	return 0;
 }