drm/i915: Move generic link training code to a separate file

No functional changes, just moving code around.

v2: Rebase

Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Reviewed-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1445594525-7174-6-git-send-email-ander.conselvan.de.oliveira@intel.com

4 files changed, 353 insertions, 312 deletions

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 44d290ae1999..0851de07bd13 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -77,6 +77,7 @@ i915-y += dvo_ch7017.o \
 	  dvo_tfp410.o \
 	  intel_crt.o \
 	  intel_ddi.o \
+	  intel_dp_link_training.o \
 	  intel_dp_mst.o \
 	  intel_dp.o \
 	  intel_dsi.o \
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index cf9255efa8b1..d129507e5cff 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1189,7 +1189,7 @@ intel_dp_sink_rates(struct intel_dp *intel_dp, const int **sink_rates)
 	return (intel_dp_max_link_bw(intel_dp) >> 3) + 1;
 }
 
-static bool intel_dp_source_supports_hbr2(struct drm_device *dev)
+bool intel_dp_source_supports_hbr2(struct drm_device *dev)
 {
 	/* WaDisableHBR2:skl */
 	if (IS_SKL_REVID(dev, 0, SKL_REVID_B0))
@@ -1365,8 +1365,8 @@ int intel_dp_rate_select(struct intel_dp *intel_dp, int rate)
 	return rate_to_index(rate, intel_dp->sink_rates);
 }
 
-static void intel_dp_compute_rate(struct intel_dp *intel_dp, int port_clock,
-				  uint8_t *link_bw, uint8_t *rate_select)
+void intel_dp_compute_rate(struct intel_dp *intel_dp, int port_clock,
+			   uint8_t *link_bw, uint8_t *rate_select)
 {
 	if (intel_dp->num_sink_rates) {
 		*link_bw = 0;
@@ -3046,7 +3046,7 @@ intel_dp_dpcd_read_wake(struct drm_dp_aux *aux, unsigned int offset,
  * Fetch AUX CH registers 0x202 - 0x207 which contain
  * link status information
  */
-static bool
+bool
 intel_dp_get_link_status(struct intel_dp *intel_dp, uint8_t link_status[DP_LINK_STATUS_SIZE])
 {
 	return intel_dp_dpcd_read_wake(&intel_dp->aux,
@@ -3056,7 +3056,7 @@ intel_dp_get_link_status(struct intel_dp *intel_dp, uint8_t link_status[DP_LINK_
 }
 
 /* These are source-specific values. */
-static uint8_t
+uint8_t
 intel_dp_voltage_max(struct intel_dp *intel_dp)
 {
 	struct drm_device *dev = intel_dp_to_dev(intel_dp);
@@ -3079,7 +3079,7 @@ intel_dp_voltage_max(struct intel_dp *intel_dp)
 		return DP_TRAIN_VOLTAGE_SWING_LEVEL_2;
 }
 
-static uint8_t
+uint8_t
 intel_dp_pre_emphasis_max(struct intel_dp *intel_dp, uint8_t voltage_swing)
 {
 	struct drm_device *dev = intel_dp_to_dev(intel_dp);
@@ -3421,38 +3421,6 @@ static uint32_t chv_signal_levels(struct intel_dp *intel_dp)
 	return 0;
 }
 
-static void
-intel_get_adjust_train(struct intel_dp *intel_dp,
-		       const uint8_t link_status[DP_LINK_STATUS_SIZE])
-{
-	uint8_t v = 0;
-	uint8_t p = 0;
-	int lane;
-	uint8_t voltage_max;
-	uint8_t preemph_max;
-
-	for (lane = 0; lane < intel_dp->lane_count; lane++) {
-		uint8_t this_v = drm_dp_get_adjust_request_voltage(link_status, lane);
-		uint8_t this_p = drm_dp_get_adjust_request_pre_emphasis(link_status, lane);
-
-		if (this_v > v)
-			v = this_v;
-		if (this_p > p)
-			p = this_p;
-	}
-
-	voltage_max = intel_dp_voltage_max(intel_dp);
-	if (v >= voltage_max)
-		v = voltage_max | DP_TRAIN_MAX_SWING_REACHED;
-
-	preemph_max = intel_dp_pre_emphasis_max(intel_dp, v);
-	if (p >= preemph_max)
-		p = preemph_max | DP_TRAIN_MAX_PRE_EMPHASIS_REACHED;
-
-	for (lane = 0; lane < 4; lane++)
-		intel_dp->train_set[lane] = v | p;
-}
-
 static uint32_t
 gen4_signal_levels(uint8_t train_set)
 {
@@ -3550,7 +3518,7 @@ gen7_edp_signal_levels(uint8_t train_set)
 	}
 }
 
-static void
+void
 intel_dp_set_signal_levels(struct intel_dp *intel_dp)
 {
 	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
@@ -3597,7 +3565,7 @@ intel_dp_set_signal_levels(struct intel_dp *intel_dp)
 	POSTING_READ(intel_dp->output_reg);
 }
 
-static void
+void
 intel_dp_program_link_training_pattern(struct intel_dp *intel_dp,
 				       uint8_t dp_train_pat)
 {
@@ -3611,56 +3579,7 @@ intel_dp_program_link_training_pattern(struct intel_dp *intel_dp,
 	POSTING_READ(intel_dp->output_reg);
 }
 
-static bool
-intel_dp_set_link_train(struct intel_dp *intel_dp,
-			uint8_t dp_train_pat)
-{
-	uint8_t buf[sizeof(intel_dp->train_set) + 1];
-	int ret, len;
-
-	intel_dp_program_link_training_pattern(intel_dp, dp_train_pat);
-
-	buf[0] = dp_train_pat;
-	if ((dp_train_pat & DP_TRAINING_PATTERN_MASK) ==
-	    DP_TRAINING_PATTERN_DISABLE) {
-		/* don't write DP_TRAINING_LANEx_SET on disable */
-		len = 1;
-	} else {
-		/* DP_TRAINING_LANEx_SET follow DP_TRAINING_PATTERN_SET */
-		memcpy(buf + 1, intel_dp->train_set, intel_dp->lane_count);
-		len = intel_dp->lane_count + 1;
-	}
-
-	ret = drm_dp_dpcd_write(&intel_dp->aux, DP_TRAINING_PATTERN_SET,
-				buf, len);
-
-	return ret == len;
-}
-
-static bool
-intel_dp_reset_link_train(struct intel_dp *intel_dp,
-			uint8_t dp_train_pat)
-{
-	if (!intel_dp->train_set_valid)
-		memset(intel_dp->train_set, 0, sizeof(intel_dp->train_set));
-	intel_dp_set_signal_levels(intel_dp);
-	return intel_dp_set_link_train(intel_dp, dp_train_pat);
-}
-
-static bool
-intel_dp_update_link_train(struct intel_dp *intel_dp)
-{
-	int ret;
-
-	intel_dp_set_signal_levels(intel_dp);
-
-	ret = drm_dp_dpcd_write(&intel_dp->aux, DP_TRAINING_LANE0_SET,
-				intel_dp->train_set, intel_dp->lane_count);
-
-	return ret == intel_dp->lane_count;
-}
-
-static void intel_dp_set_idle_link_train(struct intel_dp *intel_dp)
+void intel_dp_set_idle_link_train(struct intel_dp *intel_dp)
 {
 	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
 	struct drm_device *dev = intel_dig_port->base.base.dev;
@@ -3691,228 +3610,6 @@ static void intel_dp_set_idle_link_train(struct intel_dp *intel_dp)
 		DRM_ERROR("Timed out waiting for DP idle patterns\n");
 }
 
-/* Enable corresponding port and start training pattern 1 */
-static void
-intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp)
-{
-	struct drm_encoder *encoder = &dp_to_dig_port(intel_dp)->base.base;
-	struct drm_device *dev = encoder->dev;
-	int i;
-	uint8_t voltage;
-	int voltage_tries, loop_tries;
-	uint8_t link_config[2];
-	uint8_t link_bw, rate_select;
-
-	if (HAS_DDI(dev))
-		intel_ddi_prepare_link_retrain(encoder);
-
-	intel_dp_compute_rate(intel_dp, intel_dp->link_rate,
-			      &link_bw, &rate_select);
-
-	/* Write the link configuration data */
-	link_config[0] = link_bw;
-	link_config[1] = intel_dp->lane_count;
-	if (drm_dp_enhanced_frame_cap(intel_dp->dpcd))
-		link_config[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
-	drm_dp_dpcd_write(&intel_dp->aux, DP_LINK_BW_SET, link_config, 2);
-	if (intel_dp->num_sink_rates)
-		drm_dp_dpcd_write(&intel_dp->aux, DP_LINK_RATE_SET,
-				  &rate_select, 1);
-
-	link_config[0] = 0;
-	link_config[1] = DP_SET_ANSI_8B10B;
-	drm_dp_dpcd_write(&intel_dp->aux, DP_DOWNSPREAD_CTRL, link_config, 2);
-
-	intel_dp->DP |= DP_PORT_EN;
-
-	/* clock recovery */
-	if (!intel_dp_reset_link_train(intel_dp,
-				       DP_TRAINING_PATTERN_1 |
-				       DP_LINK_SCRAMBLING_DISABLE)) {
-		DRM_ERROR("failed to enable link training\n");
-		return;
-	}
-
-	voltage = 0xff;
-	voltage_tries = 0;
-	loop_tries = 0;
-	for (;;) {
-		uint8_t link_status[DP_LINK_STATUS_SIZE];
-
-		drm_dp_link_train_clock_recovery_delay(intel_dp->dpcd);
-		if (!intel_dp_get_link_status(intel_dp, link_status)) {
-			DRM_ERROR("failed to get link status\n");
-			break;
-		}
-
-		if (drm_dp_clock_recovery_ok(link_status, intel_dp->lane_count)) {
-			DRM_DEBUG_KMS("clock recovery OK\n");
-			break;
-		}
-
-		/*
-		 * if we used previously trained voltage and pre-emphasis values
-		 * and we don't get clock recovery, reset link training values
-		 */
-		if (intel_dp->train_set_valid) {
-			DRM_DEBUG_KMS("clock recovery not ok, reset");
-			/* clear the flag as we are not reusing train set */
-			intel_dp->train_set_valid = false;
-			if (!intel_dp_reset_link_train(intel_dp,
-						       DP_TRAINING_PATTERN_1 |
-						       DP_LINK_SCRAMBLING_DISABLE)) {
-				DRM_ERROR("failed to enable link training\n");
-				return;
-			}
-			continue;
-		}
-
-		/* Check to see if we've tried the max voltage */
-		for (i = 0; i < intel_dp->lane_count; i++)
-			if ((intel_dp->train_set[i] & DP_TRAIN_MAX_SWING_REACHED) == 0)
-				break;
-		if (i == intel_dp->lane_count) {
-			++loop_tries;
-			if (loop_tries == 5) {
-				DRM_ERROR("too many full retries, give up\n");
-				break;
-			}
-			intel_dp_reset_link_train(intel_dp,
-						  DP_TRAINING_PATTERN_1 |
-						  DP_LINK_SCRAMBLING_DISABLE);
-			voltage_tries = 0;
-			continue;
-		}
-
-		/* Check to see if we've tried the same voltage 5 times */
-		if ((intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK) == voltage) {
-			++voltage_tries;
-			if (voltage_tries == 5) {
-				DRM_ERROR("too many voltage retries, give up\n");
-				break;
-			}
-		} else
-			voltage_tries = 0;
-		voltage = intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK;
-
-		/* Update training set as requested by target */
-		intel_get_adjust_train(intel_dp, link_status);
-		if (!intel_dp_update_link_train(intel_dp)) {
-			DRM_ERROR("failed to update link training\n");
-			break;
-		}
-	}
-}
-
-static void
-intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
-{
-	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
-	struct drm_device *dev = dig_port->base.base.dev;
-	bool channel_eq = false;
-	int tries, cr_tries;
-	uint32_t training_pattern = DP_TRAINING_PATTERN_2;
-
-	/*
-	 * Training Pattern 3 for HBR2 or 1.2 devices that support it.
-	 *
-	 * Intel platforms that support HBR2 also support TPS3. TPS3 support is
-	 * also mandatory for downstream devices that support HBR2.
-	 *
-	 * Due to WaDisableHBR2 SKL < B0 is the only exception where TPS3 is
-	 * supported but still not enabled.
-	 */
-	if (intel_dp_source_supports_hbr2(dev) &&
-	    drm_dp_tps3_supported(intel_dp->dpcd))
-		training_pattern = DP_TRAINING_PATTERN_3;
-	else if (intel_dp->link_rate == 540000)
-		DRM_ERROR("5.4 Gbps link rate without HBR2/TPS3 support\n");
-
-	/* channel equalization */
-	if (!intel_dp_set_link_train(intel_dp,
-				     training_pattern |
-				     DP_LINK_SCRAMBLING_DISABLE)) {
-		DRM_ERROR("failed to start channel equalization\n");
-		return;
-	}
-
-	tries = 0;
-	cr_tries = 0;
-	channel_eq = false;
-	for (;;) {
-		uint8_t link_status[DP_LINK_STATUS_SIZE];
-
-		if (cr_tries > 5) {
-			DRM_ERROR("failed to train DP, aborting\n");
-			break;
-		}
-
-		drm_dp_link_train_channel_eq_delay(intel_dp->dpcd);
-		if (!intel_dp_get_link_status(intel_dp, link_status)) {
-			DRM_ERROR("failed to get link status\n");
-			break;
-		}
-
-		/* Make sure clock is still ok */
-		if (!drm_dp_clock_recovery_ok(link_status,
-					      intel_dp->lane_count)) {
-			intel_dp->train_set_valid = false;
-			intel_dp_link_training_clock_recovery(intel_dp);
-			intel_dp_set_link_train(intel_dp,
-						training_pattern |
-						DP_LINK_SCRAMBLING_DISABLE);
-			cr_tries++;
-			continue;
-		}
-
-		if (drm_dp_channel_eq_ok(link_status,
-					 intel_dp->lane_count)) {
-			channel_eq = true;
-			break;
-		}
-
-		/* Try 5 times, then try clock recovery if that fails */
-		if (tries > 5) {
-			intel_dp->train_set_valid = false;
-			intel_dp_link_training_clock_recovery(intel_dp);
-			intel_dp_set_link_train(intel_dp,
-						training_pattern |
-						DP_LINK_SCRAMBLING_DISABLE);
-			tries = 0;
-			cr_tries++;
-			continue;
-		}
-
-		/* Update training set as requested by target */
-		intel_get_adjust_train(intel_dp, link_status);
-		if (!intel_dp_update_link_train(intel_dp)) {
-			DRM_ERROR("failed to update link training\n");
-			break;
-		}
-		++tries;
-	}
-
-	intel_dp_set_idle_link_train(intel_dp);
-
-	if (channel_eq) {
-		intel_dp->train_set_valid = true;
-		DRM_DEBUG_KMS("Channel EQ done. DP Training successful\n");
-	}
-}
-
-void intel_dp_stop_link_train(struct intel_dp *intel_dp)
-{
-	intel_dp_set_link_train(intel_dp,
-				DP_TRAINING_PATTERN_DISABLE);
-}
-
-void
-intel_dp_start_link_train(struct intel_dp *intel_dp)
-{
-	intel_dp_link_training_clock_recovery(intel_dp);
-	intel_dp_link_training_channel_equalization(intel_dp);
-}
-
 static void
 intel_dp_link_down(struct intel_dp *intel_dp)
 {
diff --git a/drivers/gpu/drm/i915/intel_dp_link_training.c b/drivers/gpu/drm/i915/intel_dp_link_training.c
new file mode 100644
index 000000000000..53f9c1439db4
--- /dev/null
+++ b/drivers/gpu/drm/i915/intel_dp_link_training.c
@@ -0,0 +1,327 @@
+/*
+ * Copyright © 2008-2015 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "intel_drv.h"
+
+static void
+intel_get_adjust_train(struct intel_dp *intel_dp,
+		       const uint8_t link_status[DP_LINK_STATUS_SIZE])
+{
+	uint8_t v = 0;
+	uint8_t p = 0;
+	int lane;
+	uint8_t voltage_max;
+	uint8_t preemph_max;
+
+	for (lane = 0; lane < intel_dp->lane_count; lane++) {
+		uint8_t this_v = drm_dp_get_adjust_request_voltage(link_status, lane);
+		uint8_t this_p = drm_dp_get_adjust_request_pre_emphasis(link_status, lane);
+
+		if (this_v > v)
+			v = this_v;
+		if (this_p > p)
+			p = this_p;
+	}
+
+	voltage_max = intel_dp_voltage_max(intel_dp);
+	if (v >= voltage_max)
+		v = voltage_max | DP_TRAIN_MAX_SWING_REACHED;
+
+	preemph_max = intel_dp_pre_emphasis_max(intel_dp, v);
+	if (p >= preemph_max)
+		p = preemph_max | DP_TRAIN_MAX_PRE_EMPHASIS_REACHED;
+
+	for (lane = 0; lane < 4; lane++)
+		intel_dp->train_set[lane] = v | p;
+}
+
+static bool
+intel_dp_set_link_train(struct intel_dp *intel_dp,
+			uint8_t dp_train_pat)
+{
+	uint8_t buf[sizeof(intel_dp->train_set) + 1];
+	int ret, len;
+
+	intel_dp_program_link_training_pattern(intel_dp, dp_train_pat);
+
+	buf[0] = dp_train_pat;
+	if ((dp_train_pat & DP_TRAINING_PATTERN_MASK) ==
+	    DP_TRAINING_PATTERN_DISABLE) {
+		/* don't write DP_TRAINING_LANEx_SET on disable */
+		len = 1;
+	} else {
+		/* DP_TRAINING_LANEx_SET follow DP_TRAINING_PATTERN_SET */
+		memcpy(buf + 1, intel_dp->train_set, intel_dp->lane_count);
+		len = intel_dp->lane_count + 1;
+	}
+
+	ret = drm_dp_dpcd_write(&intel_dp->aux, DP_TRAINING_PATTERN_SET,
+				buf, len);
+
+	return ret == len;
+}
+
+static bool
+intel_dp_reset_link_train(struct intel_dp *intel_dp,
+			uint8_t dp_train_pat)
+{
+	if (!intel_dp->train_set_valid)
+		memset(intel_dp->train_set, 0, sizeof(intel_dp->train_set));
+	intel_dp_set_signal_levels(intel_dp);
+	return intel_dp_set_link_train(intel_dp, dp_train_pat);
+}
+
+static bool
+intel_dp_update_link_train(struct intel_dp *intel_dp)
+{
+	int ret;
+
+	intel_dp_set_signal_levels(intel_dp);
+
+	ret = drm_dp_dpcd_write(&intel_dp->aux, DP_TRAINING_LANE0_SET,
+				intel_dp->train_set, intel_dp->lane_count);
+
+	return ret == intel_dp->lane_count;
+}
+
+/* Enable corresponding port and start training pattern 1 */
+static void
+intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp)
+{
+	struct drm_encoder *encoder = &dp_to_dig_port(intel_dp)->base.base;
+	struct drm_device *dev = encoder->dev;
+	int i;
+	uint8_t voltage;
+	int voltage_tries, loop_tries;
+	uint8_t link_config[2];
+	uint8_t link_bw, rate_select;
+
+	if (HAS_DDI(dev))
+		intel_ddi_prepare_link_retrain(encoder);
+
+	intel_dp_compute_rate(intel_dp, intel_dp->link_rate,
+			      &link_bw, &rate_select);
+
+	/* Write the link configuration data */
+	link_config[0] = link_bw;
+	link_config[1] = intel_dp->lane_count;
+	if (drm_dp_enhanced_frame_cap(intel_dp->dpcd))
+		link_config[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
+	drm_dp_dpcd_write(&intel_dp->aux, DP_LINK_BW_SET, link_config, 2);
+	if (intel_dp->num_sink_rates)
+		drm_dp_dpcd_write(&intel_dp->aux, DP_LINK_RATE_SET,
+				  &rate_select, 1);
+
+	link_config[0] = 0;
+	link_config[1] = DP_SET_ANSI_8B10B;
+	drm_dp_dpcd_write(&intel_dp->aux, DP_DOWNSPREAD_CTRL, link_config, 2);
+
+	intel_dp->DP |= DP_PORT_EN;
+
+	/* clock recovery */
+	if (!intel_dp_reset_link_train(intel_dp,
+				       DP_TRAINING_PATTERN_1 |
+				       DP_LINK_SCRAMBLING_DISABLE)) {
+		DRM_ERROR("failed to enable link training\n");
+		return;
+	}
+
+	voltage = 0xff;
+	voltage_tries = 0;
+	loop_tries = 0;
+	for (;;) {
+		uint8_t link_status[DP_LINK_STATUS_SIZE];
+
+		drm_dp_link_train_clock_recovery_delay(intel_dp->dpcd);
+		if (!intel_dp_get_link_status(intel_dp, link_status)) {
+			DRM_ERROR("failed to get link status\n");
+			break;
+		}
+
+		if (drm_dp_clock_recovery_ok(link_status, intel_dp->lane_count)) {
+			DRM_DEBUG_KMS("clock recovery OK\n");
+			break;
+		}
+
+		/*
+		 * if we used previously trained voltage and pre-emphasis values
+		 * and we don't get clock recovery, reset link training values
+		 */
+		if (intel_dp->train_set_valid) {
+			DRM_DEBUG_KMS("clock recovery not ok, reset");
+			/* clear the flag as we are not reusing train set */
+			intel_dp->train_set_valid = false;
+			if (!intel_dp_reset_link_train(intel_dp,
+						       DP_TRAINING_PATTERN_1 |
+						       DP_LINK_SCRAMBLING_DISABLE)) {
+				DRM_ERROR("failed to enable link training\n");
+				return;
+			}
+			continue;
+		}
+
+		/* Check to see if we've tried the max voltage */
+		for (i = 0; i < intel_dp->lane_count; i++)
+			if ((intel_dp->train_set[i] & DP_TRAIN_MAX_SWING_REACHED) == 0)
+				break;
+		if (i == intel_dp->lane_count) {
+			++loop_tries;
+			if (loop_tries == 5) {
+				DRM_ERROR("too many full retries, give up\n");
+				break;
+			}
+			intel_dp_reset_link_train(intel_dp,
+						  DP_TRAINING_PATTERN_1 |
+						  DP_LINK_SCRAMBLING_DISABLE);
+			voltage_tries = 0;
+			continue;
+		}
+
+		/* Check to see if we've tried the same voltage 5 times */
+		if ((intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK) == voltage) {
+			++voltage_tries;
+			if (voltage_tries == 5) {
+				DRM_ERROR("too many voltage retries, give up\n");
+				break;
+			}
+		} else
+			voltage_tries = 0;
+		voltage = intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK;
+
+		/* Update training set as requested by target */
+		intel_get_adjust_train(intel_dp, link_status);
+		if (!intel_dp_update_link_train(intel_dp)) {
+			DRM_ERROR("failed to update link training\n");
+			break;
+		}
+	}
+}
+
+static void
+intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
+{
+	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+	struct drm_device *dev = dig_port->base.base.dev;
+	bool channel_eq = false;
+	int tries, cr_tries;
+	uint32_t training_pattern = DP_TRAINING_PATTERN_2;
+
+	/*
+	 * Training Pattern 3 for HBR2 or 1.2 devices that support it.
+	 *
+	 * Intel platforms that support HBR2 also support TPS3. TPS3 support is
+	 * also mandatory for downstream devices that support HBR2.
+	 *
+	 * Due to WaDisableHBR2 SKL < B0 is the only exception where TPS3 is
+	 * supported but still not enabled.
+	 */
+	if (intel_dp_source_supports_hbr2(dev) &&
+	    drm_dp_tps3_supported(intel_dp->dpcd))
+		training_pattern = DP_TRAINING_PATTERN_3;
+	else if (intel_dp->link_rate == 540000)
+		DRM_ERROR("5.4 Gbps link rate without HBR2/TPS3 support\n");
+
+	/* channel equalization */
+	if (!intel_dp_set_link_train(intel_dp,
+				     training_pattern |
+				     DP_LINK_SCRAMBLING_DISABLE)) {
+		DRM_ERROR("failed to start channel equalization\n");
+		return;
+	}
+
+	tries = 0;
+	cr_tries = 0;
+	channel_eq = false;
+	for (;;) {
+		uint8_t link_status[DP_LINK_STATUS_SIZE];
+
+		if (cr_tries > 5) {
+			DRM_ERROR("failed to train DP, aborting\n");
+			break;
+		}
+
+		drm_dp_link_train_channel_eq_delay(intel_dp->dpcd);
+		if (!intel_dp_get_link_status(intel_dp, link_status)) {
+			DRM_ERROR("failed to get link status\n");
+			break;
+		}
+
+		/* Make sure clock is still ok */
+		if (!drm_dp_clock_recovery_ok(link_status,
+					      intel_dp->lane_count)) {
+			intel_dp->train_set_valid = false;
+			intel_dp_link_training_clock_recovery(intel_dp);
+			intel_dp_set_link_train(intel_dp,
+						training_pattern |
+						DP_LINK_SCRAMBLING_DISABLE);
+			cr_tries++;
+			continue;
+		}
+
+		if (drm_dp_channel_eq_ok(link_status,
+					 intel_dp->lane_count)) {
+			channel_eq = true;
+			break;
+		}
+
+		/* Try 5 times, then try clock recovery if that fails */
+		if (tries > 5) {
+			intel_dp->train_set_valid = false;
+			intel_dp_link_training_clock_recovery(intel_dp);
+			intel_dp_set_link_train(intel_dp,
+						training_pattern |
+						DP_LINK_SCRAMBLING_DISABLE);
+			tries = 0;
+			cr_tries++;
+			continue;
+		}
+
+		/* Update training set as requested by target */
+		intel_get_adjust_train(intel_dp, link_status);
+		if (!intel_dp_update_link_train(intel_dp)) {
+			DRM_ERROR("failed to update link training\n");
+			break;
+		}
+		++tries;
+	}
+
+	intel_dp_set_idle_link_train(intel_dp);
+
+	if (channel_eq) {
+		intel_dp->train_set_valid = true;
+		DRM_DEBUG_KMS("Channel EQ done. DP Training successful\n");
+	}
+}
+
+void intel_dp_stop_link_train(struct intel_dp *intel_dp)
+{
+	intel_dp_set_link_train(intel_dp,
+				DP_TRAINING_PATTERN_DISABLE);
+}
+
+void
+intel_dp_start_link_train(struct intel_dp *intel_dp)
+{
+	intel_dp_link_training_clock_recovery(intel_dp);
+	intel_dp_link_training_channel_equalization(intel_dp);
+}
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 92c1b8567aaa..a721c50da370 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1251,6 +1251,22 @@ bool intel_digital_port_connected(struct drm_i915_private *dev_priv,
 					 struct intel_digital_port *port);
 void hsw_dp_set_ddi_pll_sel(struct intel_crtc_state *pipe_config);
 
+void
+intel_dp_program_link_training_pattern(struct intel_dp *intel_dp,
+				       uint8_t dp_train_pat);
+void
+intel_dp_set_signal_levels(struct intel_dp *intel_dp);
+void intel_dp_set_idle_link_train(struct intel_dp *intel_dp);
+uint8_t
+intel_dp_voltage_max(struct intel_dp *intel_dp);
+uint8_t
+intel_dp_pre_emphasis_max(struct intel_dp *intel_dp, uint8_t voltage_swing);
+void intel_dp_compute_rate(struct intel_dp *intel_dp, int port_clock,
+			   uint8_t *link_bw, uint8_t *rate_select);
+bool intel_dp_source_supports_hbr2(struct drm_device *dev);
+bool
+intel_dp_get_link_status(struct intel_dp *intel_dp, uint8_t link_status[DP_LINK_STATUS_SIZE]);
+
 /* intel_dp_mst.c */
 int intel_dp_mst_encoder_init(struct intel_digital_port *intel_dig_port, int conn_id);
 void intel_dp_mst_encoder_cleanup(struct intel_digital_port *intel_dig_port);