[PATCH v4 2/3] drm/mediatek: enhance the HDMI driving current

From: Bibby Hsieh
Date: Wed Aug 17 2016 - 02:58:49 EST


From: Junzhi Zhao <junzhi.zhao@xxxxxxxxxxxx>

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@xxxxxxxxxxxx>
Signed-off-by: Bibby Hsieh <bibby.hsieh@xxxxxxxxxxxx>
---
drivers/gpu/drm/mediatek/mtk_mt8173_hdmi_phy.c | 42 +++++++++++++++++-------
1 file changed, 30 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_mt8173_hdmi_phy.c b/drivers/gpu/drm/mediatek/mtk_mt8173_hdmi_phy.c
index 8a24754..51cb9cf 100644
--- a/drivers/gpu/drm/mediatek/mtk_mt8173_hdmi_phy.c
+++ b/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;
}

--
1.7.9.5