linux-kernel - [PATCH v2] drm/msm/dp: Correct LeMans/Monaco DP phy Swing/Emphasis setting

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Message-Id: <20260119-klm_dpphy-v2-1-52252190940b@oss.qualcomm.com>
Date: Mon, 19 Jan 2026 20:37:20 +0800
From: Yongxing Mou <yongxing.mou@....qualcomm.com>
To: Vinod Koul <vkoul@...nel.org>, Neil Armstrong <neil.armstrong@...aro.org>
Cc: linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Abel Vesa <abel.vesa@....qualcomm.com>,
        Yongxing Mou <yongxing.mou@....qualcomm.com>
Subject: [PATCH v2] drm/msm/dp: Correct LeMans/Monaco DP phy Swing/Emphasis
 setting

Currently, the LeMans/Monaco devices and their derivative platforms
operate in DP mode rather than eDP mode. Per the PHY HPG, the Swing and
Emphasis settings need to be corrected to the proper values.

This will help achieve successful link training on some dongles.

Cc: stable@...r.kernel.org
Fixes: 3f12bf16213c ("phy: qcom: edp: Add support for eDP PHY on SA8775P")
Reviewed-by: Abel Vesa <abel.vesa@....qualcomm.com>
Signed-off-by: Yongxing Mou <yongxing.mou@....qualcomm.com>
---
Changes in v2:
- Separate the LDO change out.[Konrad][Dmitry]
- Modify the commit message.[Dmitry]
- Link to v1: https://lore.kernel.org/r/20260109-klm_dpphy-v1-1-a6b6abe382de@oss.qualcomm.com
---
 drivers/phy/qualcomm/phy-qcom-edp.c | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/phy/qualcomm/phy-qcom-edp.c b/drivers/phy/qualcomm/phy-qcom-edp.c
index 13feab99feec..ae98f0a3cf3a 100644
--- a/drivers/phy/qualcomm/phy-qcom-edp.c
+++ b/drivers/phy/qualcomm/phy-qcom-edp.c
@@ -122,6 +122,13 @@ static const u8 dp_swing_hbr_rbr[4][4] = {
 	{ 0x1f, 0xff, 0xff, 0xff }
 };
 
+static const u8 dp_swing_hbr_rbr_v1[4][4] = {
+	{ 0x07, 0x0f, 0x16, 0x1f },
+	{ 0x11, 0x1e, 0x1f, 0xff },
+	{ 0x16, 0x1f, 0xff, 0xff },
+	{ 0x1f, 0xff, 0xff, 0xff }
+};
+
 static const u8 dp_pre_emp_hbr_rbr[4][4] = {
 	{ 0x00, 0x0d, 0x14, 0x1a },
 	{ 0x00, 0x0e, 0x15, 0xff },
@@ -129,6 +136,13 @@ static const u8 dp_pre_emp_hbr_rbr[4][4] = {
 	{ 0x03, 0xff, 0xff, 0xff }
 };
 
+static const u8 dp_pre_emp_hbr_rbr_v1[4][4] = {
+	{ 0x00, 0x0e, 0x15, 0x1a },
+	{ 0x00, 0x0e, 0x15, 0xff },
+	{ 0x00, 0x0e, 0xff, 0xff },
+	{ 0x04, 0xff, 0xff, 0xff }
+};
+
 static const u8 dp_swing_hbr2_hbr3[4][4] = {
 	{ 0x02, 0x12, 0x16, 0x1a },
 	{ 0x09, 0x19, 0x1f, 0xff },
@@ -150,6 +164,13 @@ static const struct qcom_edp_swing_pre_emph_cfg dp_phy_swing_pre_emph_cfg = {
 	.pre_emphasis_hbr3_hbr2 = &dp_pre_emp_hbr2_hbr3,
 };
 
+static const struct qcom_edp_swing_pre_emph_cfg dp_phy_swing_pre_emph_cfg_v1 = {
+	.swing_hbr_rbr = &dp_swing_hbr_rbr_v1,
+	.swing_hbr3_hbr2 = &dp_swing_hbr2_hbr3,
+	.pre_emphasis_hbr_rbr = &dp_pre_emp_hbr_rbr_v1,
+	.pre_emphasis_hbr3_hbr2 = &dp_pre_emp_hbr2_hbr3,
+};
+
 static const u8 edp_swing_hbr_rbr[4][4] = {
 	{ 0x07, 0x0f, 0x16, 0x1f },
 	{ 0x0d, 0x16, 0x1e, 0xff },
@@ -564,7 +585,7 @@ static const struct qcom_edp_phy_cfg sa8775p_dp_phy_cfg = {
 	.is_edp = false,
 	.aux_cfg = edp_phy_aux_cfg_v5,
 	.vco_div_cfg = edp_phy_vco_div_cfg_v4,
-	.swing_pre_emph_cfg = &edp_phy_swing_pre_emph_cfg_v5,
+	.swing_pre_emph_cfg = &dp_phy_swing_pre_emph_cfg_v1,
 	.ver_ops = &qcom_edp_phy_ops_v4,
 };
 

---
base-commit: fc4e91c639c0af93d63c3d5bc0ee45515dd7504a
change-id: 20260109-klm_dpphy-8b3a95750f78

Best regards,
-- 
Yongxing Mou <yongxing.mou@....qualcomm.com>