[v15,13/14] drm/i915/dp: Enable Upfront link training for typeC DP support on HSW/BDW/SKL/BXT (DDI platforms)

Commit Message

Navare, Manasi Sept. 8, 2016, 8:02 p.m. UTC

From: Durgadoss R <[e-mail]>

To support USB type C alternate DP mode, the display driver needs to
know the number of lanes required by the DP panel as well as number
of lanes that can be supported by the type-C cable. Sometimes, the
type-C cable may limit the bandwidth even if Panel can support
more lanes. To address these scenarios, the display driver will
start link training with max lanes, and if that fails, the driver
falls back to x2 lanes; and repeats this procedure for all
bandwidth/lane configurations.

* Since link training is done before modeset only the port
  (and not pipe/planes) and its associated PLLs are enabled.
* On DP hotplug: Directly start link training on the DP encoder.
* On Connected boot scenarios: When booted with an LFP and a DP,
  sometimes BIOS brings up DP. In these cases, we disable the
  crtc and then do upfront link training; and bring it back up.
* All local changes made for upfront link training are reset
  to their previous values once it is done; so that the
  subsequent modeset is not aware of these changes.

Changes since v14:
* Rebased on new revision of compute config patch (Manasi)
Changes since v13:
* Fix some indentation issues (Mika Kahola)
Changes since v12:
* Fix Rebase issues (Mika Kahola)
Changes since v11:
* Change the fallback link rate logic (Manasi)
Changes since v10:
* Use the ddi link train function that loops through all the link rates
and lane counts starting from the highest supported (Manasi)
* For upfront link training, set the upfront flag so that the link can
be disabled after caching upfront values (Manasi)
Changes since v9:
* Change the macros to use dev_priv in place of dev (David Weinehall)
Changes since v8:
* Reset upfront lane count and link rate values on HPD
for DP connector physical disconnect (Manasi)
Changes since v7:
* Move the upfront link training to intel_dp_mode_valid()
  to avoid a race condition with DP MST sideband comms. (Ville)
Changes since v6:
* Fix some initialization bugs on link_rate (Jim Bride)
* Use link_rate (and not link_bw) for upfront (Ville)
* Make intel_dp_upfront*() as a vfunc (Ander)
* The train_set_valid variable in intel_dp was removed due to
  issues in fast link training. So, to indicate the link train
  status, move the channel_eq inside intel_dp.
Changes since v5:
* Moved retry logic in upfront to intel_dp.c so that it
  can be used for all platforms.
Changes since v4:
* Removed usage of crtc_state in upfront link training;
  Hence no need to find free crtc to do upfront now.
* Re-enable crtc if it was disabled for upfront.
* Use separate variables to track max lane count
  and link rate found by upfront, without modifying
  the original DPCD read from panel.
Changes since v3:
* Fixed a return value on BXT check
* Reworked on top of bxt_ddi_pll_select split from Ander
* Renamed from ddi_upfront to bxt_upfront since the
  upfront logic includes BXT specific functions for now.
Changes since v2:
* Rebased on top of latest dpll_mgr.c code and
  latest HPD related clean ups.
* Corrected return values from upfront (Ander)
* Corrected atomic locking for upfront in intel_dp.c (Ville)
Changes since v1:
*  all pll related functions inside ddi.c

Signed-off-by: Durgadoss R <[e-mail]>
Signed-off-by: Jim Bride <[e-mail]>
Signed-off-by: Manasi Navare <[e-mail]>
---
 drivers/gpu/drm/i915/intel_ddi.c              |  21 +-
 drivers/gpu/drm/i915/intel_dp.c               | 377 +++++++++++++++++++-------
 drivers/gpu/drm/i915/intel_dp_link_training.c |   1 -
 drivers/gpu/drm/i915/intel_drv.h              |  14 +-
 4 files changed, 312 insertions(+), 101 deletions(-)

Comments

Jani Nikula Sept. 9, 2016, 7:34 a.m. UTC | #1

On Thu, 08 Sep 2016, Manasi Navare <[e-mail]> wrote:
> From: Durgadoss R <[e-mail]>
>
> To support USB type C alternate DP mode, the display driver needs to
> know the number of lanes required by the DP panel as well as number
> of lanes that can be supported by the type-C cable. Sometimes, the
> type-C cable may limit the bandwidth even if Panel can support
> more lanes. To address these scenarios, the display driver will
> start link training with max lanes, and if that fails, the driver
> falls back to x2 lanes; and repeats this procedure for all
> bandwidth/lane configurations.
>
> * Since link training is done before modeset only the port
>   (and not pipe/planes) and its associated PLLs are enabled.
> * On DP hotplug: Directly start link training on the DP encoder.
> * On Connected boot scenarios: When booted with an LFP and a DP,
>   sometimes BIOS brings up DP. In these cases, we disable the
>   crtc and then do upfront link training; and bring it back up.
> * All local changes made for upfront link training are reset
>   to their previous values once it is done; so that the
>   subsequent modeset is not aware of these changes.

As I said for a previous version, this needs to be split to functional
and non-functional parts.

> @@ -5618,6 +5794,13 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
>  	if (type == DRM_MODE_CONNECTOR_eDP)
>  		intel_encoder->type = INTEL_OUTPUT_EDP;
>  
> +	/* Initialize upfront link training vfunc for DP */
> +	if (intel_encoder->type != INTEL_OUTPUT_EDP) {
> +		if (IS_BROXTON(dev_priv) || IS_SKYLAKE(dev_priv) ||
> +		    IS_BROADWELL(dev_priv) || IS_HASWELL(dev_priv))

What's this based on? What happened to Kabylake?

> +			intel_dp->upfront_link_train = intel_ddi_link_train;
> +	}
> +
>  	/* eDP only on port B and/or C on vlv/chv */
>  	if (WARN_ON((IS_VALLEYVIEW(dev) || IS_CHERRYVIEW(dev)) &&
>  		    is_edp(intel_dp) && port != PORT_B && port != PORT_C))
> diff --git a/drivers/gpu/drm/i915/intel_dp_link_training.c b/drivers/gpu/drm/i915/intel_dp_link_training.c
> index f1e08f0..b6f380b 100644
> --- a/drivers/gpu/drm/i915/intel_dp_link_training.c
> +++ b/drivers/gpu/drm/i915/intel_dp_link_training.c
> @@ -304,7 +304,6 @@ intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
>  	intel_dp_set_idle_link_train(intel_dp);
>  
>  	return intel_dp->channel_eq_status;
> -
>  }
>  
>  void intel_dp_stop_link_train(struct intel_dp *intel_dp)
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 5b97a7d4..e5ab375 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -882,6 +882,12 @@ struct intel_dp {
>  	enum hdmi_force_audio force_audio;
>  	bool limited_color_range;
>  	bool color_range_auto;
> +
> +	/* Upfront link train parameters */
> +	int max_link_rate_upfront;
> +	uint8_t max_lanes_upfront;
> +	bool upfront_done;
> +
>  	uint8_t dpcd[DP_RECEIVER_CAP_SIZE];
>  	uint8_t psr_dpcd[EDP_PSR_RECEIVER_CAP_SIZE];
>  	uint8_t downstream_ports[DP_MAX_DOWNSTREAM_PORTS];
> @@ -939,6 +945,11 @@ struct intel_dp {
>  	/* This is called before a link training is starterd */
>  	void (*prepare_link_retrain)(struct intel_dp *intel_dp);
>  
> +	/* For Upfront link training */
> +	bool (*upfront_link_train)(struct intel_dp *intel_dp, int clock,
> +				   uint8_t lane_count, bool link_mst,
> +				   bool is_upfront);
> +
>  	/* Displayport compliance testing */
>  	unsigned long compliance_test_type;
>  	unsigned long compliance_test_data;
> @@ -1161,7 +1172,8 @@ void intel_ddi_clock_get(struct intel_encoder *encoder,
>  void intel_ddi_set_vc_payload_alloc(struct drm_crtc *crtc, bool state);
>  uint32_t ddi_signal_levels(struct intel_dp *intel_dp);
>  bool intel_ddi_link_train(struct intel_dp *intel_dp, int max_link_rate,
> -			  uint8_t max_lane_count, bool link_mst);
> +			  uint8_t max_lane_count, bool link_mst,
> +			  bool is_upfront);
>  struct intel_shared_dpll *intel_ddi_get_link_dpll(struct intel_dp *intel_dp,
>  						  int clock);
>  unsigned int intel_fb_align_height(struct drm_device *dev,

Patch

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 1278daa..797c3bb 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1673,7 +1673,8 @@  static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
 	pll->config.crtc_mask = 0;
 
 	/* If Link Training fails, send a uevent to generate a hotplug */
-	if (!(intel_ddi_link_train(intel_dp, link_rate, lane_count, link_mst)))
+	if (!(intel_ddi_link_train(intel_dp, link_rate, lane_count, link_mst,
+				   false)))
 		drm_kms_helper_hotplug_event(encoder->base.dev);
 	pll->config = tmp_pll_config;
 }
@@ -2461,7 +2462,7 @@  intel_ddi_get_link_dpll(struct intel_dp *intel_dp, int clock)
 
 bool
 intel_ddi_link_train(struct intel_dp *intel_dp, int max_link_rate,
-		     uint8_t max_lane_count, bool link_mst)
+		     uint8_t max_lane_count, bool link_mst, bool is_upfront)
 {
 	struct intel_connector *connector = intel_dp->attached_connector;
 	struct intel_encoder *encoder = connector->encoder;
@@ -2507,6 +2508,7 @@  intel_ddi_link_train(struct intel_dp *intel_dp, int max_link_rate,
 			pll->funcs.disable(dev_priv, pll);
 			pll->config = tmp_pll_config;
 		}
+
 		if (ret) {
 			DRM_DEBUG_KMS("Link Training successful at link rate: "
 				      "%d lane:%d\n", link_rate, lane_count);
@@ -2515,6 +2517,21 @@  intel_ddi_link_train(struct intel_dp *intel_dp, int max_link_rate,
 	}
 	intel_dp_stop_link_train(intel_dp);
 
+	if (is_upfront) {
+		DRM_DEBUG_KMS("Upfront link train %s: link_clock:%d lanes:%d\n",
+			      ret ? "Passed" : "Failed",
+			      link_rate, lane_count);
+		/* Disable port followed by PLL for next retry/clean up */
+		intel_ddi_post_disable(encoder, NULL, NULL);
+		pll->funcs.disable(dev_priv, pll);
+		pll->config = tmp_pll_config;
+		if (ret) {
+			/* Save the upfront values */
+			intel_dp->max_lanes_upfront = lane_count;
+			intel_dp->max_link_rate_upfront = link_rate;
+		}
+	}
+
 	if (!lane_count)
 		DRM_ERROR("Link Training Failed\n");
 
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 60c8857..7adf093 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -153,12 +153,21 @@  intel_dp_max_link_bw(struct intel_dp  *intel_dp)
 static u8 intel_dp_max_lane_count(struct intel_dp *intel_dp)
 {
 	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
-	u8 source_max, sink_max;
+	u8 temp, source_max, sink_max;
 
 	source_max = intel_dig_port->max_lanes;
 	sink_max = drm_dp_max_lane_count(intel_dp->dpcd);
 
-	return min(source_max, sink_max);
+	temp = min(source_max, sink_max);
+
+	/*
+	 * Limit max lanes w.r.t to the max value found
+	 * using Upfront link training also.
+	 */
+	if (intel_dp->max_lanes_upfront)
+		return min(temp, intel_dp->max_lanes_upfront);
+	else
+		return temp;
 }
 
 /*
@@ -190,6 +199,230 @@  intel_dp_max_data_rate(int max_link_clock, int max_lanes)
 	return (max_link_clock * max_lanes * 8) / 10;
 }
 
+static int intel_dp_upfront_crtc_disable(struct intel_crtc *crtc,
+					 struct drm_modeset_acquire_ctx *ctx,
+					 bool enable)
+{
+	int ret;
+	struct drm_atomic_state *state;
+	struct intel_crtc_state *crtc_state;
+	struct drm_device *dev = crtc->base.dev;
+	enum pipe pipe = crtc->pipe;
+
+	state = drm_atomic_state_alloc(dev);
+	if (!state)
+		return -ENOMEM;
+
+	state->acquire_ctx = ctx;
+
+	crtc_state = intel_atomic_get_crtc_state(state, crtc);
+	if (IS_ERR(crtc_state)) {
+		ret = PTR_ERR(crtc_state);
+		drm_atomic_state_free(state);
+		return ret;
+	}
+
+	DRM_DEBUG_KMS("%sabling crtc %c %s upfront link train\n",
+			enable ? "En" : "Dis",
+			pipe_name(pipe),
+			enable ? "after" : "before");
+
+	crtc_state->base.active = enable;
+	ret = drm_atomic_commit(state);
+	if (ret)
+		drm_atomic_state_free(state);
+
+	return ret;
+}
+
+static int
+intel_dp_sink_rates(struct intel_dp *intel_dp, const int **sink_rates)
+{
+	if (intel_dp->num_sink_rates) {
+		*sink_rates = intel_dp->sink_rates;
+		return intel_dp->num_sink_rates;
+	}
+
+	*sink_rates = default_rates;
+
+	return (intel_dp_max_link_bw(intel_dp) >> 3) + 1;
+}
+
+bool intel_dp_source_supports_hbr2(struct intel_dp *intel_dp)
+{
+	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+	struct drm_i915_private *dev_priv = to_i915(dig_port->base.base.dev);
+
+	/* WaDisableHBR2:skl */
+	if (IS_SKL_REVID(dev_priv, 0, SKL_REVID_B0))
+		return false;
+
+	if ((IS_HASWELL(dev_priv) && !IS_HSW_ULX(dev_priv)) ||
+	    IS_BROADWELL(dev_priv) || (INTEL_GEN(dev_priv) >= 9))
+		return true;
+	else
+		return false;
+}
+
+static int
+intel_dp_source_rates(struct intel_dp *intel_dp, const int **source_rates)
+{
+	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+	struct drm_i915_private *dev_priv = to_i915(dig_port->base.base.dev);
+	int size;
+
+	if (IS_BROXTON(dev_priv)) {
+		*source_rates = bxt_rates;
+		size = ARRAY_SIZE(bxt_rates);
+	} else if (IS_SKYLAKE(dev_priv) || IS_KABYLAKE(dev_priv)) {
+		*source_rates = skl_rates;
+		size = ARRAY_SIZE(skl_rates);
+	} else {
+		*source_rates = default_rates;
+		size = ARRAY_SIZE(default_rates);
+	}
+
+	/* This depends on the fact that 5.4 is last value in the array */
+	if (!intel_dp_source_supports_hbr2(intel_dp))
+		size--;
+
+	return size;
+}
+
+static int intersect_rates(const int *source_rates, int source_len,
+			   const int *sink_rates, int sink_len,
+			   int *common_rates)
+{
+	int i = 0, j = 0, k = 0;
+
+	while (i < source_len && j < sink_len) {
+		if (source_rates[i] == sink_rates[j]) {
+			if (WARN_ON(k >= DP_MAX_SUPPORTED_RATES))
+				return k;
+			common_rates[k] = source_rates[i];
+			++k;
+			++i;
+			++j;
+		} else if (source_rates[i] < sink_rates[j]) {
+			++i;
+		} else {
+			++j;
+		}
+	}
+	return k;
+}
+
+static int intel_dp_common_rates(struct intel_dp *intel_dp,
+				 int *common_rates)
+{
+	const int *source_rates, *sink_rates;
+	int source_len, sink_len;
+
+	sink_len = intel_dp_sink_rates(intel_dp, &sink_rates);
+
+	/* Cap sink rates w.r.t upfront values */
+	if (intel_dp->max_link_rate_upfront) {
+		int len = sink_len - 1;
+
+		while (len > 0 && sink_rates[len] >
+		       intel_dp->max_link_rate_upfront)
+			len--;
+		sink_len = len + 1;
+	}
+
+	source_len = intel_dp_source_rates(intel_dp, &source_rates);
+
+	return intersect_rates(source_rates, source_len,
+			       sink_rates, sink_len,
+			       common_rates);
+}
+
+static bool intel_dp_upfront_link_train(struct intel_dp *intel_dp)
+{
+	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
+	struct intel_encoder *intel_encoder = &intel_dig_port->base;
+	struct drm_device *dev = intel_encoder->base.dev;
+	struct drm_i915_private *dev_priv = to_i915(dev);
+	struct drm_mode_config *config = &dev->mode_config;
+	struct drm_modeset_acquire_ctx ctx;
+	struct intel_crtc *intel_crtc;
+	struct drm_crtc *crtc = NULL;
+	struct intel_shared_dpll *pll;
+	struct intel_shared_dpll_config tmp_pll_config;
+	bool disable_dpll = false;
+	int ret;
+	bool done = false, has_mst = false;
+	uint8_t max_lanes;
+	int common_rates[DP_MAX_SUPPORTED_RATES] = {};
+	int common_len;
+	enum intel_display_power_domain power_domain;
+
+	power_domain = intel_display_port_power_domain(intel_encoder);
+	intel_display_power_get(dev_priv, power_domain);
+
+	common_len = intel_dp_common_rates(intel_dp, common_rates);
+	max_lanes = intel_dp_max_lane_count(intel_dp);
+	if (WARN_ON(common_len <= 0))
+		return true;
+
+	drm_modeset_acquire_init(&ctx, 0);
+retry:
+	ret = drm_modeset_lock(&config->connection_mutex, &ctx);
+	if (ret)
+		goto exit_fail;
+
+	if (intel_encoder->base.crtc) {
+		crtc = intel_encoder->base.crtc;
+
+		ret = drm_modeset_lock(&crtc->mutex, &ctx);
+		if (ret)
+			goto exit_fail;
+
+		ret = drm_modeset_lock(&crtc->primary->mutex, &ctx);
+		if (ret)
+			goto exit_fail;
+
+		intel_crtc = to_intel_crtc(crtc);
+		pll = intel_crtc->config->shared_dpll;
+		disable_dpll = true;
+		has_mst = intel_crtc_has_type(intel_crtc->config,
+					      INTEL_OUTPUT_DP_MST);
+		ret = intel_dp_upfront_crtc_disable(intel_crtc, &ctx, false);
+		if (ret)
+			goto exit_fail;
+	}
+
+	mutex_lock(&dev_priv->dpll_lock);
+	if (disable_dpll) {
+		/* Clear the PLL config state */
+		tmp_pll_config = pll->config;
+		pll->config.crtc_mask = 0;
+	}
+
+	done = intel_dp->upfront_link_train(intel_dp,
+					    common_rates[common_len-1],
+					    max_lanes,
+					    has_mst,
+					    true);
+	if (disable_dpll)
+		pll->config = tmp_pll_config;
+
+	mutex_unlock(&dev_priv->dpll_lock);
+
+	if (crtc)
+		ret = intel_dp_upfront_crtc_disable(intel_crtc, &ctx, true);
+
+exit_fail:
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry;
+	}
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+	intel_display_power_put(dev_priv, power_domain);
+	return done;
+}
+
 static enum drm_mode_status
 intel_dp_mode_valid(struct drm_connector *connector,
 		    struct drm_display_mode *mode)
@@ -211,6 +444,19 @@  intel_dp_mode_valid(struct drm_connector *connector,
 		target_clock = fixed_mode->clock;
 	}
 
+	if (intel_dp->upfront_link_train && !intel_dp->upfront_done) {
+		bool do_upfront_link_train;
+		/* Do not do upfront link train, if it is a compliance
+		 * request
+		 */
+		do_upfront_link_train = !intel_dp->upfront_done &&
+			(intel_dp->compliance_test_type !=
+			 DP_TEST_LINK_TRAINING);
+
+		if (do_upfront_link_train)
+			intel_dp->upfront_done = intel_dp_upfront_link_train(intel_dp);
+	}
+
 	max_link_clock = intel_dp_max_link_rate(intel_dp);
 	max_lanes = intel_dp_max_lane_count(intel_dp);
 
@@ -1256,60 +1502,6 @@  intel_dp_aux_init(struct intel_dp *intel_dp, struct intel_connector *connector)
 	intel_dp->aux.transfer = intel_dp_aux_transfer;
 }
 
-static int
-intel_dp_sink_rates(struct intel_dp *intel_dp, const int **sink_rates)
-{
-	if (intel_dp->num_sink_rates) {
-		*sink_rates = intel_dp->sink_rates;
-		return intel_dp->num_sink_rates;
-	}
-
-	*sink_rates = default_rates;
-
-	return (intel_dp_max_link_bw(intel_dp) >> 3) + 1;
-}
-
-bool intel_dp_source_supports_hbr2(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;
-
-	/* WaDisableHBR2:skl */
-	if (IS_SKL_REVID(dev, 0, SKL_REVID_B0))
-		return false;
-
-	if ((IS_HASWELL(dev) && !IS_HSW_ULX(dev)) || IS_BROADWELL(dev) ||
-	    (INTEL_INFO(dev)->gen >= 9))
-		return true;
-	else
-		return false;
-}
-
-static int
-intel_dp_source_rates(struct intel_dp *intel_dp, const int **source_rates)
-{
-	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
-	struct drm_device *dev = dig_port->base.base.dev;
-	int size;
-
-	if (IS_BROXTON(dev)) {
-		*source_rates = bxt_rates;
-		size = ARRAY_SIZE(bxt_rates);
-	} else if (IS_SKYLAKE(dev) || IS_KABYLAKE(dev)) {
-		*source_rates = skl_rates;
-		size = ARRAY_SIZE(skl_rates);
-	} else {
-		*source_rates = default_rates;
-		size = ARRAY_SIZE(default_rates);
-	}
-
-	/* This depends on the fact that 5.4 is last value in the array */
-	if (!intel_dp_source_supports_hbr2(intel_dp))
-		size--;
-
-	return size;
-}
-
 static void
 intel_dp_set_clock(struct intel_encoder *encoder,
 		   struct intel_crtc_state *pipe_config)
@@ -1343,42 +1535,6 @@  intel_dp_set_clock(struct intel_encoder *encoder,
 	}
 }
 
-static int intersect_rates(const int *source_rates, int source_len,
-			   const int *sink_rates, int sink_len,
-			   int *common_rates)
-{
-	int i = 0, j = 0, k = 0;
-
-	while (i < source_len && j < sink_len) {
-		if (source_rates[i] == sink_rates[j]) {
-			if (WARN_ON(k >= DP_MAX_SUPPORTED_RATES))
-				return k;
-			common_rates[k] = source_rates[i];
-			++k;
-			++i;
-			++j;
-		} else if (source_rates[i] < sink_rates[j]) {
-			++i;
-		} else {
-			++j;
-		}
-	}
-	return k;
-}
-
-static int intel_dp_common_rates(struct intel_dp *intel_dp,
-				 int *common_rates)
-{
-	const int *source_rates, *sink_rates;
-	int source_len, sink_len;
-
-	sink_len = intel_dp_sink_rates(intel_dp, &sink_rates);
-	source_len = intel_dp_source_rates(intel_dp, &source_rates);
-
-	return intersect_rates(source_rates, source_len,
-			       sink_rates, sink_len,
-			       common_rates);
-}
 
 static void snprintf_int_array(char *str, size_t len,
 			       const int *array, int nelem)
@@ -1436,6 +1592,9 @@  intel_dp_max_link_rate(struct intel_dp *intel_dp)
 	int rates[DP_MAX_SUPPORTED_RATES] = {};
 	int len;
 
+	if (intel_dp->max_link_rate_upfront)
+		return intel_dp->max_link_rate_upfront;
+
 	len = intel_dp_common_rates(intel_dp, rates);
 	if (WARN_ON(len <= 0))
 		return 162000;
@@ -1488,7 +1647,7 @@  intel_dp_compute_config(struct intel_encoder *encoder,
 	enum port port = dp_to_dig_port(intel_dp)->port;
 	struct intel_crtc *intel_crtc = to_intel_crtc(pipe_config->base.crtc);
 	struct intel_connector *intel_connector = intel_dp->attached_connector;
-	int lane_count, clock;
+	int lane_count, clock = 0;
 	int min_lane_count = 1;
 	int max_lane_count = intel_dp_max_lane_count(intel_dp);
 	/* Conveniently, the link BW constants become indices with a shift...*/
@@ -1567,6 +1726,21 @@  intel_dp_compute_config(struct intel_encoder *encoder,
 	for (; bpp >= 6*3; bpp -= 2*3) {
 		mode_rate = intel_dp_link_required(adjusted_mode->crtc_clock,
 						   bpp);
+
+		if (!is_edp(intel_dp) && intel_dp->upfront_done) {
+			clock = max_clock;
+			lane_count = intel_dp->max_lanes_upfront;
+			link_clock = intel_dp->max_link_rate_upfront;
+			link_avail = intel_dp_max_data_rate(link_clock,
+							    lane_count);
+			mode_rate = intel_dp_link_required(adjusted_mode->crtc_clock,
+							   bpp);
+			if (mode_rate <= link_avail)
+				goto found;
+			else
+				continue;
+		}
+
 		clock = max_clock;
 		lane_count = max_lane_count;
 		link_clock = common_rates[clock];
@@ -1595,7 +1769,6 @@  found:
 	}
 
 	pipe_config->lane_count = lane_count;
-
 	pipe_config->pipe_bpp = bpp;
 	pipe_config->port_clock = common_rates[clock];
 
@@ -4279,7 +4452,7 @@  intel_dp_long_pulse(struct intel_connector *intel_connector)
 	struct drm_device *dev = connector->dev;
 	enum drm_connector_status status;
 	enum intel_display_power_domain power_domain;
-	u8 sink_irq_vector = 0;
+	u8 sink_irq_vector;
 
 	power_domain = intel_display_port_aux_power_domain(intel_encoder);
 	intel_display_power_get(to_i915(dev), power_domain);
@@ -4372,9 +4545,12 @@  intel_dp_long_pulse(struct intel_connector *intel_connector)
 	}
 
 out:
-	if ((status != connector_status_connected) &&
-	    (intel_dp->is_mst == false))
+	if (status != connector_status_connected) {
 		intel_dp_unset_edid(intel_dp);
+		intel_dp->upfront_done = false;
+		intel_dp->max_lanes_upfront = 0;
+		intel_dp->max_link_rate_upfront = 0;
+	}
 
 	intel_display_power_put(to_i915(dev), power_domain);
 	return;
@@ -5618,6 +5794,13 @@  intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
 	if (type == DRM_MODE_CONNECTOR_eDP)
 		intel_encoder->type = INTEL_OUTPUT_EDP;
 
+	/* Initialize upfront link training vfunc for DP */
+	if (intel_encoder->type != INTEL_OUTPUT_EDP) {
+		if (IS_BROXTON(dev_priv) || IS_SKYLAKE(dev_priv) ||
+		    IS_BROADWELL(dev_priv) || IS_HASWELL(dev_priv))
+			intel_dp->upfront_link_train = intel_ddi_link_train;
+	}
+
 	/* eDP only on port B and/or C on vlv/chv */
 	if (WARN_ON((IS_VALLEYVIEW(dev) || IS_CHERRYVIEW(dev)) &&
 		    is_edp(intel_dp) && port != PORT_B && port != PORT_C))
diff --git a/drivers/gpu/drm/i915/intel_dp_link_training.c b/drivers/gpu/drm/i915/intel_dp_link_training.c
index f1e08f0..b6f380b 100644
--- a/drivers/gpu/drm/i915/intel_dp_link_training.c
+++ b/drivers/gpu/drm/i915/intel_dp_link_training.c
@@ -304,7 +304,6 @@  intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
 	intel_dp_set_idle_link_train(intel_dp);
 
 	return intel_dp->channel_eq_status;
-
 }
 
 void intel_dp_stop_link_train(struct intel_dp *intel_dp)
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 5b97a7d4..e5ab375 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -882,6 +882,12 @@  struct intel_dp {
 	enum hdmi_force_audio force_audio;
 	bool limited_color_range;
 	bool color_range_auto;
+
+	/* Upfront link train parameters */
+	int max_link_rate_upfront;
+	uint8_t max_lanes_upfront;
+	bool upfront_done;
+
 	uint8_t dpcd[DP_RECEIVER_CAP_SIZE];
 	uint8_t psr_dpcd[EDP_PSR_RECEIVER_CAP_SIZE];
 	uint8_t downstream_ports[DP_MAX_DOWNSTREAM_PORTS];
@@ -939,6 +945,11 @@  struct intel_dp {
 	/* This is called before a link training is starterd */
 	void (*prepare_link_retrain)(struct intel_dp *intel_dp);
 
+	/* For Upfront link training */
+	bool (*upfront_link_train)(struct intel_dp *intel_dp, int clock,
+				   uint8_t lane_count, bool link_mst,
+				   bool is_upfront);
+
 	/* Displayport compliance testing */
 	unsigned long compliance_test_type;
 	unsigned long compliance_test_data;
@@ -1161,7 +1172,8 @@  void intel_ddi_clock_get(struct intel_encoder *encoder,
 void intel_ddi_set_vc_payload_alloc(struct drm_crtc *crtc, bool state);
 uint32_t ddi_signal_levels(struct intel_dp *intel_dp);
 bool intel_ddi_link_train(struct intel_dp *intel_dp, int max_link_rate,
-			  uint8_t max_lane_count, bool link_mst);
+			  uint8_t max_lane_count, bool link_mst,
+			  bool is_upfront);
 struct intel_shared_dpll *intel_ddi_get_link_dpll(struct intel_dp *intel_dp,
 						  int clock);
 unsigned int intel_fb_align_height(struct drm_device *dev,