3 files changed, 50 insertions, 15 deletions

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 26a0a570f92e..fb961bb81903 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1265,6 +1265,8 @@ static void intel_ddi_pre_enable(struct intel_encoder *intel_encoder)
                 intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
                 intel_dp_start_link_train(intel_dp);
                 intel_dp_complete_link_train(intel_dp);
+                if (port != PORT_A)
+                        intel_dp_stop_link_train(intel_dp);
         }
 }
 
@@ -1326,6 +1328,9 @@ static void intel_enable_ddi(struct intel_encoder *intel_encoder)
         } else if (type == INTEL_OUTPUT_EDP) {
                 struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
 
+                if (port == PORT_A)
+                        intel_dp_stop_link_train(intel_dp);
+
                 ironlake_edp_backlight_on(intel_dp);
         }
 
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 0ab9813a79b5..93694da7f717 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1379,6 +1379,7 @@ static void intel_enable_dp(struct intel_encoder *encoder)
         ironlake_edp_panel_on(intel_dp);
         ironlake_edp_panel_vdd_off(intel_dp, true);
         intel_dp_complete_link_train(intel_dp);
+        intel_dp_stop_link_train(intel_dp);
         ironlake_edp_backlight_on(intel_dp);
 }
 
@@ -1701,10 +1702,9 @@ intel_dp_set_link_train(struct intel_dp *intel_dp,
         struct drm_i915_private *dev_priv = dev->dev_private;
         enum port port = intel_dig_port->port;
         int ret;
-        uint32_t temp;
 
         if (HAS_DDI(dev)) {
-                temp = I915_READ(DP_TP_CTL(port));
+                uint32_t temp = I915_READ(DP_TP_CTL(port));
 
                 if (dp_train_pat & DP_LINK_SCRAMBLING_DISABLE)
                         temp |= DP_TP_CTL_SCRAMBLE_DISABLE;
@@ -1714,18 +1714,6 @@ intel_dp_set_link_train(struct intel_dp *intel_dp,
                 temp &= ~DP_TP_CTL_LINK_TRAIN_MASK;
                 switch (dp_train_pat & DP_TRAINING_PATTERN_MASK) {
                 case DP_TRAINING_PATTERN_DISABLE:
-
-                        if (port != PORT_A) {
-                                temp |= DP_TP_CTL_LINK_TRAIN_IDLE;
-                                I915_WRITE(DP_TP_CTL(port), temp);
-
-                                if (wait_for((I915_READ(DP_TP_STATUS(port)) &
-                                              DP_TP_STATUS_IDLE_DONE), 1))
-                                        DRM_ERROR("Timed out waiting for DP idle patterns\n");
-
-                                temp &= ~DP_TP_CTL_LINK_TRAIN_MASK;
-                        }
-
                         temp |= DP_TP_CTL_LINK_TRAIN_NORMAL;
 
                         break;
@@ -1801,6 +1789,37 @@ intel_dp_set_link_train(struct intel_dp *intel_dp,
         return true;
 }
 
+static 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;
+        struct drm_i915_private *dev_priv = dev->dev_private;
+        enum port port = intel_dig_port->port;
+        uint32_t val;
+
+        if (!HAS_DDI(dev))
+                return;
+
+        val = I915_READ(DP_TP_CTL(port));
+        val &= ~DP_TP_CTL_LINK_TRAIN_MASK;
+        val |= DP_TP_CTL_LINK_TRAIN_IDLE;
+        I915_WRITE(DP_TP_CTL(port), val);
+
+        /*
+         * On PORT_A we can have only eDP in SST mode. There the only reason
+         * we need to set idle transmission mode is to work around a HW issue
+         * where we enable the pipe while not in idle link-training mode.
+         * In this case there is requirement to wait for a minimum number of
+         * idle patterns to be sent.
+         */
+        if (port == PORT_A)
+                return;
+
+        if (wait_for((I915_READ(DP_TP_STATUS(port)) & DP_TP_STATUS_IDLE_DONE),
+                     1))
+                DRM_ERROR("Timed out waiting for DP idle patterns\n");
+}
+
 /* Enable corresponding port and start training pattern 1 */
 void
 intel_dp_start_link_train(struct intel_dp *intel_dp)
@@ -1943,10 +1962,19 @@ intel_dp_complete_link_train(struct intel_dp *intel_dp)
                 ++tries;
         }
 
+        intel_dp_set_idle_link_train(intel_dp);
+
+        intel_dp->DP = DP;
+
         if (channel_eq)
                 DRM_DEBUG_KMS("Channel EQ done. DP Training successfull\n");
 
-        intel_dp_set_link_train(intel_dp, DP, DP_TRAINING_PATTERN_DISABLE);
+}
+
+void intel_dp_stop_link_train(struct intel_dp *intel_dp)
+{
+        intel_dp_set_link_train(intel_dp, intel_dp->DP,
+                                DP_TRAINING_PATTERN_DISABLE);
 }
 
 static void
@@ -2154,6 +2182,7 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
                               drm_get_encoder_name(&intel_encoder->base));
                 intel_dp_start_link_train(intel_dp);
                 intel_dp_complete_link_train(intel_dp);
+                intel_dp_stop_link_train(intel_dp);
         }
 }
 
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index b5b6d19e6dd3..624a9e6b8d71 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -499,6 +499,7 @@ extern void intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
 extern void intel_dp_init_link_config(struct intel_dp *intel_dp);
 extern void intel_dp_start_link_train(struct intel_dp *intel_dp);
 extern void intel_dp_complete_link_train(struct intel_dp *intel_dp);
+extern void intel_dp_stop_link_train(struct intel_dp *intel_dp);
 extern void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode);
 extern void intel_dp_encoder_destroy(struct drm_encoder *encoder);
 extern void intel_dp_check_link_status(struct intel_dp *intel_dp);