linux-kernel - [v2 3/3] drm/msm/dsi: Add 10nm dsi phy tuning configuration support

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Date:   Mon, 10 Jan 2022 18:25:37 +0530
From:   Rajeev Nandan <quic_rajeevny@...cinc.com>
To:     dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        freedreno@...ts.freedesktop.org, devicetree@...r.kernel.org
Cc:     Rajeev Nandan <quic_rajeevny@...cinc.com>,
        linux-kernel@...r.kernel.org, sean@...rly.run, robdclark@...il.com,
        robh+dt@...nel.org, robh@...nel.org, quic_abhinavk@...cinc.com,
        quic_kalyant@...cinc.com, quic_mkrishn@...cinc.com,
        jonathan@...ek.ca, dmitry.baryshkov@...aro.org, airlied@...ux.ie,
        daniel@...ll.ch, swboyd@...omium.org
Subject: [v2 3/3] drm/msm/dsi: Add 10nm dsi phy tuning configuration support

The clock and data lanes of the DSI PHY have a calibration circuitry
feature. As per the MSM DSI PHY tuning guidelines, the drive strength
tuning can be done by adjusting rescode offset for hstop/hsbot, and
the drive level tuning can be done by adjusting the LDO output level
for the HSTX drive.

Signed-off-by: Rajeev Nandan <quic_rajeevny@...cinc.com>
---

Changes in v2:
 - Split into generic code and 10nm-specific part (Dmitry Baryshkov)
 - Fix the backward compatibility (Dmitry Baryshkov)

 drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c | 51 ++++++++++++++++++++++++++----
 1 file changed, 45 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c
index d8128f5..40cd0f7 100644
--- a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c
+++ b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c
@@ -775,10 +775,13 @@ static void dsi_phy_hw_v3_0_lane_settings(struct msm_dsi_phy *phy)
 		dsi_phy_write(lane_base + REG_DSI_10nm_PHY_LN_CFG2(i), 0x0);
 		dsi_phy_write(lane_base + REG_DSI_10nm_PHY_LN_CFG3(i),
 			      i == 4 ? 0x80 : 0x0);
-		dsi_phy_write(lane_base +
-			      REG_DSI_10nm_PHY_LN_OFFSET_TOP_CTRL(i), 0x0);
-		dsi_phy_write(lane_base +
-			      REG_DSI_10nm_PHY_LN_OFFSET_BOT_CTRL(i), 0x0);
+
+		/* platform specific dsi phy drive strength adjustment */
+		dsi_phy_write(lane_base + REG_DSI_10nm_PHY_LN_OFFSET_TOP_CTRL(i),
+				phy->tuning_cfg.rescode_offset_top[i]);
+		dsi_phy_write(lane_base + REG_DSI_10nm_PHY_LN_OFFSET_BOT_CTRL(i),
+				phy->tuning_cfg.rescode_offset_bot[i]);
+
 		dsi_phy_write(lane_base + REG_DSI_10nm_PHY_LN_TX_DCTRL(i),
 			      tx_dctrl[i]);
 	}
@@ -834,8 +837,9 @@ static int dsi_10nm_phy_enable(struct msm_dsi_phy *phy,
 	/* Select MS1 byte-clk */
 	dsi_phy_write(base + REG_DSI_10nm_PHY_CMN_GLBL_CTRL, 0x10);
 
-	/* Enable LDO */
-	dsi_phy_write(base + REG_DSI_10nm_PHY_CMN_VREG_CTRL, 0x59);
+	/* Enable LDO with platform specific drive level/amplitude adjustment */
+	dsi_phy_write(base + REG_DSI_10nm_PHY_CMN_VREG_CTRL,
+		      phy->tuning_cfg.vreg_ctrl);
 
 	/* Configure PHY lane swap (TODO: we need to calculate this) */
 	dsi_phy_write(base + REG_DSI_10nm_PHY_CMN_LANE_CFG0, 0x21);
@@ -922,6 +926,39 @@ static void dsi_10nm_phy_disable(struct msm_dsi_phy *phy)
 	DBG("DSI%d PHY disabled", phy->id);
 }
 
+static void dsi_10nm_phy_tuning_cfg_init(struct msm_dsi_phy *phy)
+{
+	struct device *dev = &phy->pdev->dev;
+	u8 offset_top[DSI_LANE_MAX] = { 0 }; /* No offset */
+	u8 offset_bot[DSI_LANE_MAX] = { 0 }; /* No offset */
+	u8 ldo_level = 0x1; /* 400mV */
+	int ret, i;
+
+	/* Drive strength adjustment parameters */
+	ret = of_property_read_u8_array(dev->of_node, "phy-resocde-offset-top",
+					offset_top, DSI_LANE_MAX);
+	if (ret && ret != -EINVAL)
+		DRM_DEV_ERROR(dev, "failed to parse phy-resocde-offset-top, %d\n", ret);
+
+	for (i = 0; i < DSI_LANE_MAX; i++)
+		phy->tuning_cfg.rescode_offset_top[i] = 0x3f & offset_top[i];
+
+	ret = of_property_read_u8_array(dev->of_node, "phy-resocde-offset-bot",
+					offset_bot, DSI_LANE_MAX);
+	if (ret && ret != -EINVAL)
+		DRM_DEV_ERROR(dev, "failed to parse phy-resocde-offset-bot, %d\n", ret);
+
+	for (i = 0; i < DSI_LANE_MAX; i++)
+		phy->tuning_cfg.rescode_offset_bot[i] = 0x3f & offset_bot[i];
+
+	/* Drive level/amplitude adjustment parameters */
+	ret = of_property_read_u8(dev->of_node, "phy-drive-ldo-level", &ldo_level);
+	if (ret && ret != -EINVAL)
+		DRM_DEV_ERROR(dev, "failed to parse phy-drive-ldo-level, %d\n", ret);
+
+	phy->tuning_cfg.vreg_ctrl = 0x58 | (0x7 & ldo_level);
+}
+
 const struct msm_dsi_phy_cfg dsi_phy_10nm_cfgs = {
 	.has_phy_lane = true,
 	.reg_cfg = {
@@ -936,6 +973,7 @@ const struct msm_dsi_phy_cfg dsi_phy_10nm_cfgs = {
 		.pll_init = dsi_pll_10nm_init,
 		.save_pll_state = dsi_10nm_pll_save_state,
 		.restore_pll_state = dsi_10nm_pll_restore_state,
+		.tuning_cfg_init = dsi_10nm_phy_tuning_cfg_init,
 	},
 	.min_pll_rate = 1000000000UL,
 	.max_pll_rate = 3500000000UL,
@@ -957,6 +995,7 @@ const struct msm_dsi_phy_cfg dsi_phy_10nm_8998_cfgs = {
 		.pll_init = dsi_pll_10nm_init,
 		.save_pll_state = dsi_10nm_pll_save_state,
 		.restore_pll_state = dsi_10nm_pll_restore_state,
+		.tuning_cfg_init = dsi_10nm_phy_tuning_cfg_init,
 	},
 	.min_pll_rate = 1000000000UL,
 	.max_pll_rate = 3500000000UL,
-- 
2.7.4