diff mbox series

[v2,2/2] drm/msm/dp: Introduce link training per-segment for LTTPRs

Message ID 20250311234109.136510-3-alex.vinarskis@gmail.com (mailing list archive)
State New
Headers show
Series drm/msm/dp: Introduce link training per-segment for LTTPRs | expand

Commit Message

Aleksandrs Vinarskis March 11, 2025, 11:38 p.m. UTC 
DisplayPort requires per-segment link training when LTTPR are switched
to non-transparent mode, starting with LTTPR closest to the source.
Only when each segment is trained individually, source can link train
to sink.

Implement per-segment link traning when LTTPR(s) are detected, to
support external docking stations. On higher level, changes are:

* Pass phy being trained down to all required helpers
* Run CR, EQ link training per phy
* Set voltage swing, pre-emphasis levels per phy

This ensures successful link training both when connected directly to
the monitor (single LTTPR onboard most X1E laptops) and via the docking
station (at least two LTTPRs).

Signed-off-by: Aleksandrs Vinarskis <alex.vinarskis@gmail.com>
Reviewed-by: Abel Vesa <abel.vesa@linaro.org>
---
 drivers/gpu/drm/msm/dp/dp_ctrl.c    | 137 +++++++++++++++++++---------
 drivers/gpu/drm/msm/dp/dp_ctrl.h    |   2 +-
 drivers/gpu/drm/msm/dp/dp_display.c |   4 +-
 3 files changed, 99 insertions(+), 44 deletions(-)
diff mbox series

Patch

diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
index d8633a596f8d..419a519ccf6b 100644
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
@@ -79,6 +79,8 @@  struct msm_dp_ctrl_private {
 	struct msm_dp_link *link;
 	struct msm_dp_catalog *catalog;
 
+	int *lttpr_count;
+
 	struct phy *phy;
 
 	unsigned int num_core_clks;
@@ -1034,9 +1036,11 @@  static int msm_dp_ctrl_set_vx_px(struct msm_dp_ctrl_private *ctrl,
 	return 0;
 }
 
-static int msm_dp_ctrl_update_vx_px(struct msm_dp_ctrl_private *ctrl)
+static int msm_dp_ctrl_update_phy_vx_px(struct msm_dp_ctrl_private *ctrl,
+					enum drm_dp_phy dp_phy)
 {
 	struct msm_dp_link *link = ctrl->link;
+	int reg = DP_TRAINING_LANE0_SET;
 	int ret = 0, lane, lane_cnt;
 	u8 buf[4];
 	u32 max_level_reached = 0;
@@ -1075,8 +1079,11 @@  static int msm_dp_ctrl_update_vx_px(struct msm_dp_ctrl_private *ctrl)
 
 	drm_dbg_dp(ctrl->drm_dev, "sink: p|v=0x%x\n",
 			voltage_swing_level | pre_emphasis_level);
-	ret = drm_dp_dpcd_write(ctrl->aux, DP_TRAINING_LANE0_SET,
-					buf, lane_cnt);
+
+	if (dp_phy != DP_PHY_DPRX)
+		reg = DP_TRAINING_LANE0_SET_PHY_REPEATER(dp_phy);
+
+	ret = drm_dp_dpcd_write(ctrl->aux, reg, buf, lane_cnt);
 	if (ret == lane_cnt)
 		ret = 0;
 
@@ -1084,9 +1091,10 @@  static int msm_dp_ctrl_update_vx_px(struct msm_dp_ctrl_private *ctrl)
 }
 
 static bool msm_dp_ctrl_train_pattern_set(struct msm_dp_ctrl_private *ctrl,
-		u8 pattern)
+		u8 pattern, enum drm_dp_phy dp_phy)
 {
 	u8 buf;
+	int reg = DP_TRAINING_PATTERN_SET;
 	int ret = 0;
 
 	drm_dbg_dp(ctrl->drm_dev, "sink: pattern=%x\n", pattern);
@@ -1096,7 +1104,10 @@  static bool msm_dp_ctrl_train_pattern_set(struct msm_dp_ctrl_private *ctrl,
 	if (pattern && pattern != DP_TRAINING_PATTERN_4)
 		buf |= DP_LINK_SCRAMBLING_DISABLE;
 
-	ret = drm_dp_dpcd_writeb(ctrl->aux, DP_TRAINING_PATTERN_SET, buf);
+	if (dp_phy != DP_PHY_DPRX)
+		reg = DP_TRAINING_PATTERN_SET_PHY_REPEATER(dp_phy);
+
+	ret = drm_dp_dpcd_writeb(ctrl->aux, reg, buf);
 	return ret == 1;
 }
 
@@ -1115,12 +1126,16 @@  static int msm_dp_ctrl_read_link_status(struct msm_dp_ctrl_private *ctrl,
 }
 
 static int msm_dp_ctrl_link_train_1(struct msm_dp_ctrl_private *ctrl,
-			int *training_step)
+			int *training_step, enum drm_dp_phy dp_phy)
 {
+	int delay_us;
 	int tries, old_v_level, ret = 0;
 	u8 link_status[DP_LINK_STATUS_SIZE];
 	int const maximum_retries = 4;
 
+	delay_us = drm_dp_read_clock_recovery_delay(ctrl->aux,
+		ctrl->panel->dpcd, dp_phy, false);
+
 	msm_dp_catalog_ctrl_state_ctrl(ctrl->catalog, 0);
 
 	*training_step = DP_TRAINING_1;
@@ -1129,18 +1144,19 @@  static int msm_dp_ctrl_link_train_1(struct msm_dp_ctrl_private *ctrl,
 	if (ret)
 		return ret;
 	msm_dp_ctrl_train_pattern_set(ctrl, DP_TRAINING_PATTERN_1 |
-		DP_LINK_SCRAMBLING_DISABLE);
+		DP_LINK_SCRAMBLING_DISABLE, dp_phy);
 
-	ret = msm_dp_ctrl_update_vx_px(ctrl);
+	msm_dp_link_reset_phy_params_vx_px(ctrl->link);
+	ret = msm_dp_ctrl_update_phy_vx_px(ctrl, dp_phy);
 	if (ret)
 		return ret;
 
 	tries = 0;
 	old_v_level = ctrl->link->phy_params.v_level;
 	for (tries = 0; tries < maximum_retries; tries++) {
-		drm_dp_link_train_clock_recovery_delay(ctrl->aux, ctrl->panel->dpcd);
+		fsleep(delay_us);
 
-		ret = msm_dp_ctrl_read_link_status(ctrl, link_status);
+		ret = drm_dp_dpcd_read_phy_link_status(ctrl->aux, dp_phy, link_status);
 		if (ret)
 			return ret;
 
@@ -1161,7 +1177,7 @@  static int msm_dp_ctrl_link_train_1(struct msm_dp_ctrl_private *ctrl,
 		}
 
 		msm_dp_link_adjust_levels(ctrl->link, link_status);
-		ret = msm_dp_ctrl_update_vx_px(ctrl);
+		ret = msm_dp_ctrl_update_phy_vx_px(ctrl, dp_phy);
 		if (ret)
 			return ret;
 	}
@@ -1213,21 +1229,31 @@  static int msm_dp_ctrl_link_lane_down_shift(struct msm_dp_ctrl_private *ctrl)
 	return 0;
 }
 
-static void msm_dp_ctrl_clear_training_pattern(struct msm_dp_ctrl_private *ctrl)
+static void msm_dp_ctrl_clear_training_pattern(struct msm_dp_ctrl_private *ctrl,
+					       enum drm_dp_phy dp_phy)
 {
-	msm_dp_ctrl_train_pattern_set(ctrl, DP_TRAINING_PATTERN_DISABLE);
-	drm_dp_link_train_channel_eq_delay(ctrl->aux, ctrl->panel->dpcd);
+	int delay_us;
+
+	msm_dp_ctrl_train_pattern_set(ctrl, DP_TRAINING_PATTERN_DISABLE, dp_phy);
+
+	delay_us = drm_dp_read_channel_eq_delay(ctrl->aux,
+		ctrl->panel->dpcd, dp_phy, false);
+	fsleep(delay_us);
 }
 
 static int msm_dp_ctrl_link_train_2(struct msm_dp_ctrl_private *ctrl,
-			int *training_step)
+			int *training_step, enum drm_dp_phy dp_phy)
 {
+	int delay_us;
 	int tries = 0, ret = 0;
 	u8 pattern;
 	u32 state_ctrl_bit;
 	int const maximum_retries = 5;
 	u8 link_status[DP_LINK_STATUS_SIZE];
 
+	delay_us = drm_dp_read_channel_eq_delay(ctrl->aux,
+		ctrl->panel->dpcd, dp_phy, false);
+
 	msm_dp_catalog_ctrl_state_ctrl(ctrl->catalog, 0);
 
 	*training_step = DP_TRAINING_2;
@@ -1247,12 +1273,12 @@  static int msm_dp_ctrl_link_train_2(struct msm_dp_ctrl_private *ctrl,
 	if (ret)
 		return ret;
 
-	msm_dp_ctrl_train_pattern_set(ctrl, pattern);
+	msm_dp_ctrl_train_pattern_set(ctrl, pattern, dp_phy);
 
 	for (tries = 0; tries <= maximum_retries; tries++) {
-		drm_dp_link_train_channel_eq_delay(ctrl->aux, ctrl->panel->dpcd);
+		fsleep(delay_us);
 
-		ret = msm_dp_ctrl_read_link_status(ctrl, link_status);
+		ret = drm_dp_dpcd_read_phy_link_status(ctrl->aux, dp_phy, link_status);
 		if (ret)
 			return ret;
 
@@ -1262,7 +1288,7 @@  static int msm_dp_ctrl_link_train_2(struct msm_dp_ctrl_private *ctrl,
 		}
 
 		msm_dp_link_adjust_levels(ctrl->link, link_status);
-		ret = msm_dp_ctrl_update_vx_px(ctrl);
+		ret = msm_dp_ctrl_update_phy_vx_px(ctrl, dp_phy);
 		if (ret)
 			return ret;
 
@@ -1271,10 +1297,32 @@  static int msm_dp_ctrl_link_train_2(struct msm_dp_ctrl_private *ctrl,
 	return -ETIMEDOUT;
 }
 
+static int msm_dp_ctrl_link_train_1_2(struct msm_dp_ctrl_private *ctrl,
+				      int *training_step, enum drm_dp_phy dp_phy)
+{
+	int ret;
+
+	ret = msm_dp_ctrl_link_train_1(ctrl, training_step, dp_phy);
+	if (ret) {
+		DRM_ERROR("link training #1 on phy %d failed. ret=%d\n", dp_phy, ret);
+		return ret;
+	}
+	drm_dbg_dp(ctrl->drm_dev, "link training #1 on phy %d successful\n", dp_phy);
+
+	ret = msm_dp_ctrl_link_train_2(ctrl, training_step, dp_phy);
+	if (ret) {
+		DRM_ERROR("link training #2 on phy %d failed. ret=%d\n", dp_phy, ret);
+		return ret;
+	}
+	drm_dbg_dp(ctrl->drm_dev, "link training #2 on phy %d successful\n", dp_phy);
+
+	return 0;
+}
+
 static int msm_dp_ctrl_link_train(struct msm_dp_ctrl_private *ctrl,
 			int *training_step)
 {
-	int ret = 0;
+	int ret = 0, i;
 	const u8 *dpcd = ctrl->panel->dpcd;
 	u8 encoding[] = { 0, DP_SET_ANSI_8B10B };
 	u8 assr;
@@ -1286,8 +1334,6 @@  static int msm_dp_ctrl_link_train(struct msm_dp_ctrl_private *ctrl,
 	link_info.rate = ctrl->link->link_params.rate;
 	link_info.capabilities = DP_LINK_CAP_ENHANCED_FRAMING;
 
-	msm_dp_link_reset_phy_params_vx_px(ctrl->link);
-
 	msm_dp_aux_link_configure(ctrl->aux, &link_info);
 
 	if (drm_dp_max_downspread(dpcd))
@@ -1302,23 +1348,29 @@  static int msm_dp_ctrl_link_train(struct msm_dp_ctrl_private *ctrl,
 				&assr, 1);
 	}
 
-	ret = msm_dp_ctrl_link_train_1(ctrl, training_step);
+	for (i = *ctrl->lttpr_count - 1; i >= 0; i--) {
+		enum drm_dp_phy dp_phy = DP_PHY_LTTPR(i);
+
+		ret = msm_dp_ctrl_link_train_1_2(ctrl, training_step, dp_phy);
+		msm_dp_ctrl_clear_training_pattern(ctrl, dp_phy);
+
+		if (ret)
+			break;
+	}
+
 	if (ret) {
-		DRM_ERROR("link training #1 failed. ret=%d\n", ret);
+		DRM_ERROR("link training of LTTPR(s) failed. ret=%d\n", ret);
 		goto end;
 	}
 
-	/* print success info as this is a result of user initiated action */
-	drm_dbg_dp(ctrl->drm_dev, "link training #1 successful\n");
-
-	ret = msm_dp_ctrl_link_train_2(ctrl, training_step);
+	ret = msm_dp_ctrl_link_train_1_2(ctrl, training_step, DP_PHY_DPRX);
 	if (ret) {
-		DRM_ERROR("link training #2 failed. ret=%d\n", ret);
+		DRM_ERROR("link training on sink failed. ret=%d\n", ret);
 		goto end;
 	}
 
 	/* print success info as this is a result of user initiated action */
-	drm_dbg_dp(ctrl->drm_dev, "link training #2 successful\n");
+	drm_dbg_dp(ctrl->drm_dev, "link training on sink successful\n");
 
 end:
 	msm_dp_catalog_ctrl_state_ctrl(ctrl->catalog, 0);
@@ -1636,7 +1688,7 @@  static int msm_dp_ctrl_link_maintenance(struct msm_dp_ctrl_private *ctrl)
 	if (ret)
 		goto end;
 
-	msm_dp_ctrl_clear_training_pattern(ctrl);
+	msm_dp_ctrl_clear_training_pattern(ctrl, DP_PHY_DPRX);
 
 	msm_dp_catalog_ctrl_state_ctrl(ctrl->catalog, DP_STATE_CTRL_SEND_VIDEO);
 
@@ -1660,7 +1712,7 @@  static bool msm_dp_ctrl_send_phy_test_pattern(struct msm_dp_ctrl_private *ctrl)
 		return false;
 	}
 	msm_dp_catalog_ctrl_send_phy_pattern(ctrl->catalog, pattern_requested);
-	msm_dp_ctrl_update_vx_px(ctrl);
+	msm_dp_ctrl_update_phy_vx_px(ctrl, DP_PHY_DPRX);
 	msm_dp_link_send_test_response(ctrl->link);
 
 	pattern_sent = msm_dp_catalog_ctrl_read_phy_pattern(ctrl->catalog);
@@ -1902,7 +1954,7 @@  int msm_dp_ctrl_on_link(struct msm_dp_ctrl *msm_dp_ctrl)
 			}
 
 			/* stop link training before start re training  */
-			msm_dp_ctrl_clear_training_pattern(ctrl);
+			msm_dp_ctrl_clear_training_pattern(ctrl, DP_PHY_DPRX);
 		}
 
 		rc = msm_dp_ctrl_reinitialize_mainlink(ctrl);
@@ -1926,7 +1978,7 @@  int msm_dp_ctrl_on_link(struct msm_dp_ctrl *msm_dp_ctrl)
 		 * link training failed
 		 * end txing train pattern here
 		 */
-		msm_dp_ctrl_clear_training_pattern(ctrl);
+		msm_dp_ctrl_clear_training_pattern(ctrl, DP_PHY_DPRX);
 
 		msm_dp_ctrl_deinitialize_mainlink(ctrl);
 		rc = -ECONNRESET;
@@ -1997,7 +2049,7 @@  int msm_dp_ctrl_on_stream(struct msm_dp_ctrl *msm_dp_ctrl, bool force_link_train
 		msm_dp_ctrl_link_retrain(ctrl);
 
 	/* stop txing train pattern to end link training */
-	msm_dp_ctrl_clear_training_pattern(ctrl);
+	msm_dp_ctrl_clear_training_pattern(ctrl, DP_PHY_DPRX);
 
 	/*
 	 * Set up transfer unit values and set controller state to send
@@ -2207,7 +2259,7 @@  static int msm_dp_ctrl_clk_init(struct msm_dp_ctrl *msm_dp_ctrl)
 
 struct msm_dp_ctrl *msm_dp_ctrl_get(struct device *dev, struct msm_dp_link *link,
 			struct msm_dp_panel *panel,	struct drm_dp_aux *aux,
-			struct msm_dp_catalog *catalog,
+			struct msm_dp_catalog *catalog, int *lttpr_count,
 			struct phy *phy)
 {
 	struct msm_dp_ctrl_private *ctrl;
@@ -2242,12 +2294,13 @@  struct msm_dp_ctrl *msm_dp_ctrl_get(struct device *dev, struct msm_dp_link *link
 	init_completion(&ctrl->video_comp);
 
 	/* in parameters */
-	ctrl->panel    = panel;
-	ctrl->aux      = aux;
-	ctrl->link     = link;
-	ctrl->catalog  = catalog;
-	ctrl->dev      = dev;
-	ctrl->phy      = phy;
+	ctrl->panel       = panel;
+	ctrl->aux         = aux;
+	ctrl->link        = link;
+	ctrl->catalog     = catalog;
+	ctrl->dev         = dev;
+	ctrl->phy         = phy;
+	ctrl->lttpr_count = lttpr_count;
 
 	ret = msm_dp_ctrl_clk_init(&ctrl->msm_dp_ctrl);
 	if (ret) {
diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.h b/drivers/gpu/drm/msm/dp/dp_ctrl.h
index b7abfedbf574..3fb45b138b31 100644
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.h
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.h
@@ -27,7 +27,7 @@  irqreturn_t msm_dp_ctrl_isr(struct msm_dp_ctrl *msm_dp_ctrl);
 void msm_dp_ctrl_handle_sink_request(struct msm_dp_ctrl *msm_dp_ctrl);
 struct msm_dp_ctrl *msm_dp_ctrl_get(struct device *dev, struct msm_dp_link *link,
 			struct msm_dp_panel *panel,	struct drm_dp_aux *aux,
-			struct msm_dp_catalog *catalog,
+			struct msm_dp_catalog *catalog, int *lttpr_count,
 			struct phy *phy);
 
 void msm_dp_ctrl_reset_irq_ctrl(struct msm_dp_ctrl *msm_dp_ctrl, bool enable);
diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index d0c2dc7e6648..393ce3479a7e 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -108,6 +108,7 @@  struct msm_dp_display_private {
 	struct msm_dp_event event_list[DP_EVENT_Q_MAX];
 	spinlock_t event_lock;
 
+	int lttpr_count;
 	u8 lttpr_common_caps[DP_LTTPR_COMMON_CAP_SIZE];
 
 	bool wide_bus_supported;
@@ -397,7 +398,7 @@  static int msm_dp_display_process_hpd_high(struct msm_dp_display_private *dp)
 	if (rc)
 		goto end;
 
-	msm_dp_display_lttpr_init(dp, dpcd);
+	dp->lttpr_count = msm_dp_display_lttpr_init(dp, dpcd);
 
 	rc = msm_dp_panel_read_sink_caps(dp->panel, dp->lttpr_common_caps, connector);
 	if (rc)
@@ -798,6 +799,7 @@  static int msm_dp_init_sub_modules(struct msm_dp_display_private *dp)
 
 	dp->ctrl = msm_dp_ctrl_get(dev, dp->link, dp->panel, dp->aux,
 			       dp->catalog,
+			       &dp->lttpr_count,
 			       phy);
 	if (IS_ERR(dp->ctrl)) {
 		rc = PTR_ERR(dp->ctrl);