drm/i915/dp: use VBT provided eDP params if available

We can skip most of the link training step if we use the VBT provided
values.
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/intel_dp.c

@@ -581,6 +581,17 @@ intel_dp_mode_fixup(struct drm_encoder *encoder, struct drm_display_mode *mode,
 		mode->clock = dev_priv->panel_fixed_mode->clock;
 	}
 
+	/* Just use VBT values for eDP */
+	if (is_edp(intel_dp)) {
+		intel_dp->lane_count = dev_priv->edp.lanes;
+		intel_dp->link_bw = dev_priv->edp.rate;
+		adjusted_mode->clock = intel_dp_link_clock(intel_dp->link_bw);
+		DRM_DEBUG_KMS("eDP link bw %02x lane count %d clock %d\n",
+			      intel_dp->link_bw, intel_dp->lane_count,
+			      adjusted_mode->clock);
+		return true;
+	}
+
 	for (lane_count = 1; lane_count <= max_lane_count; lane_count <<= 1) {
 		for (clock = 0; clock <= max_clock; clock++) {
 			int link_avail = intel_dp_max_data_rate(intel_dp_link_clock(bws[clock]), lane_count);
@@ -599,19 +610,6 @@ intel_dp_mode_fixup(struct drm_encoder *encoder, struct drm_display_mode *mode,
 		}
 	}
 
-	if (is_edp(intel_dp)) {
-		/* okay we failed just pick the highest */
-		intel_dp->lane_count = max_lane_count;
-		intel_dp->link_bw = bws[max_clock];
-		adjusted_mode->clock = intel_dp_link_clock(intel_dp->link_bw);
-		DRM_DEBUG_KMS("Force picking display port link bw %02x lane "
-			      "count %d clock %d\n",
-			      intel_dp->link_bw, intel_dp->lane_count,
-			      adjusted_mode->clock);
-
-		return true;
-	}
-
 	return false;
 }
 
@@ -1088,11 +1086,21 @@ intel_get_adjust_train(struct intel_dp *intel_dp)
 }
 
 static uint32_t
-intel_dp_signal_levels(uint8_t train_set, int lane_count)
+intel_dp_signal_levels(struct intel_dp *intel_dp)
 {
+	struct drm_device *dev = intel_dp->base.base.dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
 	uint32_t signal_levels = 0;
+	u8 train_set = intel_dp->train_set[0];
+	u32 vswing = train_set & DP_TRAIN_VOLTAGE_SWING_MASK;
+	u32 preemphasis = train_set & DP_TRAIN_PRE_EMPHASIS_MASK;
+
+	if (is_edp(intel_dp)) {
+		vswing = dev_priv->edp.vswing;
+		preemphasis = dev_priv->edp.preemphasis;
+	}
 
-	switch (train_set & DP_TRAIN_VOLTAGE_SWING_MASK) {
+	switch (vswing) {
 	case DP_TRAIN_VOLTAGE_SWING_400:
 	default:
 		signal_levels |= DP_VOLTAGE_0_4;
@@ -1107,7 +1115,7 @@ intel_dp_signal_levels(uint8_t train_set, int lane_count)
 		signal_levels |= DP_VOLTAGE_1_2;
 		break;
 	}
-	switch (train_set & DP_TRAIN_PRE_EMPHASIS_MASK) {
+	switch (preemphasis) {
 	case DP_TRAIN_PRE_EMPHASIS_0:
 	default:
 		signal_levels |= DP_PRE_EMPHASIS_0;
@@ -1193,6 +1201,18 @@ intel_channel_eq_ok(struct intel_dp *intel_dp)
 	return true;
 }
 
+static bool
+intel_dp_aux_handshake_required(struct intel_dp *intel_dp)
+{
+	struct drm_device *dev = intel_dp->base.base.dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	if (is_edp(intel_dp) && dev_priv->no_aux_handshake)
+		return false;
+
+	return true;
+}
+
 static bool
 intel_dp_set_link_train(struct intel_dp *intel_dp,
 			uint32_t dp_reg_value,
@@ -1205,6 +1225,9 @@ intel_dp_set_link_train(struct intel_dp *intel_dp,
 	I915_WRITE(intel_dp->output_reg, dp_reg_value);
 	POSTING_READ(intel_dp->output_reg);
 
+	if (!intel_dp_aux_handshake_required(intel_dp))
+		return true;
+
 	intel_dp_aux_native_write_1(intel_dp,
 				    DP_TRAINING_PATTERN_SET,
 				    dp_train_pat);
@@ -1237,6 +1260,7 @@ intel_dp_start_link_train(struct intel_dp *intel_dp)
 	POSTING_READ(intel_dp->output_reg);
 	intel_wait_for_vblank(dev, intel_crtc->pipe);
 
+	if (intel_dp_aux_handshake_required(intel_dp))
 		/* Write the link configuration data */
 		intel_dp_aux_native_write(intel_dp, DP_LINK_BW_SET,
 					  intel_dp->link_configuration,
@@ -1258,7 +1282,7 @@ intel_dp_start_link_train(struct intel_dp *intel_dp)
 			signal_levels = intel_gen6_edp_signal_levels(intel_dp->train_set[0]);
 			DP = (DP & ~EDP_LINK_TRAIN_VOL_EMP_MASK_SNB) | signal_levels;
 		} else {
-			signal_levels = intel_dp_signal_levels(intel_dp->train_set[0], intel_dp->lane_count);
+			signal_levels = intel_dp_signal_levels(intel_dp);
 			DP = (DP & ~(DP_VOLTAGE_MASK|DP_PRE_EMPHASIS_MASK)) | signal_levels;
 		}
 
@@ -1272,7 +1296,10 @@ intel_dp_start_link_train(struct intel_dp *intel_dp)
 			break;
 		/* Set training pattern 1 */
 
-		udelay(100);
+		udelay(500);
+		if (intel_dp_aux_handshake_required(intel_dp)) {
+			break;
+		} else {
 			if (!intel_dp_get_link_status(intel_dp))
 				break;
 
@@ -1300,6 +1327,7 @@ intel_dp_start_link_train(struct intel_dp *intel_dp)
 			/* Compute new intel_dp->train_set as requested by target */
 			intel_get_adjust_train(intel_dp);
 		}
+	}
 
 	intel_dp->DP = DP;
 }
@@ -1325,7 +1353,7 @@ intel_dp_complete_link_train(struct intel_dp *intel_dp)
 			signal_levels = intel_gen6_edp_signal_levels(intel_dp->train_set[0]);
 			DP = (DP & ~EDP_LINK_TRAIN_VOL_EMP_MASK_SNB) | signal_levels;
 		} else {
-			signal_levels = intel_dp_signal_levels(intel_dp->train_set[0], intel_dp->lane_count);
+			signal_levels = intel_dp_signal_levels(intel_dp);
 			DP = (DP & ~(DP_VOLTAGE_MASK|DP_PRE_EMPHASIS_MASK)) | signal_levels;
 		}
 
@@ -1339,7 +1367,11 @@ intel_dp_complete_link_train(struct intel_dp *intel_dp)
 					     DP_TRAINING_PATTERN_2))
 			break;
 
-		udelay(400);
+		udelay(500);
+
+		if (!intel_dp_aux_handshake_required(intel_dp)) {
+			break;
+		} else {
 			if (!intel_dp_get_link_status(intel_dp))
 				break;
 
@@ -1356,7 +1388,7 @@ intel_dp_complete_link_train(struct intel_dp *intel_dp)
 			intel_get_adjust_train(intel_dp);
 			++tries;
 		}
-
+	}
 	if (HAS_PCH_CPT(dev) && !is_edp(intel_dp))
 		reg = DP | DP_LINK_TRAIN_OFF_CPT;
 	else