drm/i915: add DP 1.2 MST support (v0.7)

This adds DP 1.2 MST support on Haswell systems.

Notes:
a) this reworks irq handling for DP MST ports, so that we can
avoid the mode config locking in the current hpd handlers, as
we need to process up/down msgs at a better time.

Changes since v0.1:
use PORT_PCH_HOTPLUG to detect short vs long pulses
add a workqueue to deal with digital events as they can get blocked on the
main workqueue beyong mode_config mutex
fix a bunch of modeset checker warnings
acks irqs in the driver
cleanup the MST encoders

Changes since v0.2:
check irq status again in work handler
move around bring up and tear down to fix DPMS on/off
use path properties.

Changes since v0.3:
updates for mst apis
more state checker fixes
irq handling improvements
fbcon handling support
improved reference counting of link - fixes redocking.

Changes since v0.4:
handle gpu reset hpd reinit without oopsing
check link status on HPD irqs
fix suspend/resume

Changes since v0.5:
use proper functions to get max link/lane counts
fix another checker backtrace - due to connectors disappearing.
set output type in more places fro, unknown->displayport
don't talk to devices if no HPD asserted
check mst on short irqs only
check link status properly
rebase onto prepping irq changes.
drop unsued force_act

Changes since v0.6:
cleanup unused struct entry.

[airlied: fix some sparse warnings].

Reviewed-by: Todd Previte <tprevite@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

12 files changed, 934 insertions, 38 deletions

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index cad1683d8bb5..91bd167e1cb7 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -59,6 +59,7 @@ i915-y += dvo_ch7017.o \
           intel_crt.o \
           intel_ddi.o \
           intel_dp.o \
+          intel_dp_mst.o \
           intel_dsi_cmd.o \
           intel_dsi.o \
           intel_dsi_pll.o \
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 6df6506db919..d335c46ec6bc 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1717,6 +1717,13 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
                 goto out_mtrrfree;
         }
 
+        dev_priv->dp_wq = alloc_ordered_workqueue("i915-dp", 0);
+        if (dev_priv->dp_wq == NULL) {
+                DRM_ERROR("Failed to create our dp workqueue.\n");
+                ret = -ENOMEM;
+                goto out_freewq;
+        }
+
         intel_irq_init(dev);
         intel_uncore_sanitize(dev);
 
@@ -1792,6 +1799,8 @@ out_gem_unload:
         intel_teardown_gmbus(dev);
         intel_teardown_mchbar(dev);
         pm_qos_remove_request(&dev_priv->pm_qos);
+        destroy_workqueue(dev_priv->dp_wq);
+out_freewq:
         destroy_workqueue(dev_priv->wq);
 out_mtrrfree:
         arch_phys_wc_del(dev_priv->gtt.mtrr);
@@ -1892,6 +1901,7 @@ int i915_driver_unload(struct drm_device *dev)
         intel_teardown_gmbus(dev);
         intel_teardown_mchbar(dev);
 
+        destroy_workqueue(dev_priv->dp_wq);
         destroy_workqueue(dev_priv->wq);
         pm_qos_remove_request(&dev_priv->pm_qos);
 
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 83cb43a24768..a361bb9bc243 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -518,7 +518,6 @@ static int i915_drm_freeze(struct drm_device *dev)
 
                 flush_delayed_work(&dev_priv->rps.delayed_resume_work);
 
-                intel_runtime_pm_disable_interrupts(dev);
 
                 intel_suspend_gt_powersave(dev);
 
@@ -532,6 +531,9 @@ static int i915_drm_freeze(struct drm_device *dev)
                 }
                 drm_modeset_unlock_all(dev);
 
+                intel_dp_mst_suspend(dev);
+                intel_runtime_pm_disable_interrupts(dev);
+
                 intel_modeset_suspend_hw(dev);
         }
 
@@ -646,6 +648,15 @@ static int __i915_drm_thaw(struct drm_device *dev, bool restore_gtt_mappings)
 
                 intel_modeset_init_hw(dev);
 
+                {
+                        unsigned long irqflags;
+                        spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
+                        if (dev_priv->display.hpd_irq_setup)
+                                dev_priv->display.hpd_irq_setup(dev);
+                        spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
+                }
+
+                intel_dp_mst_resume(dev);
                 drm_modeset_lock_all(dev);
                 intel_modeset_setup_hw_state(dev, true);
                 drm_modeset_unlock_all(dev);
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 2dc3a922a3c8..7db16bee2997 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1595,6 +1595,15 @@ struct drm_i915_private {
         u32 short_hpd_port_mask;
         struct work_struct dig_port_work;
 
+        /*
+         * if we get a HPD irq from DP and a HPD irq from non-DP
+         * the non-DP HPD could block the workqueue on a mode config
+         * mutex getting, that userspace may have taken. However
+         * userspace is waiting on the DP workqueue to run which is
+         * blocked behind the non-DP one.
+         */
+        struct workqueue_struct *dp_wq;
+
         /* Old dri1 support infrastructure, beware the dragons ya fools entering
          * here! */
         struct i915_dri1_state dri1;
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 12d77b5368c4..07e1a409e488 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1846,7 +1846,7 @@ static inline void intel_hpd_irq_handler(struct drm_device *dev,
          * deadlock.
          */
         if (queue_dig)
-                schedule_work(&dev_priv->dig_port_work);
+                queue_work(dev_priv->dp_wq, &dev_priv->dig_port_work);
         if (queue_hp)
                 schedule_work(&dev_priv->hotplug_work);
 }
@@ -4739,7 +4739,9 @@ void intel_hpd_init(struct drm_device *dev)
         list_for_each_entry(connector, &mode_config->connector_list, head) {
                 struct intel_connector *intel_connector = to_intel_connector(connector);
                 connector->polled = intel_connector->polled;
-                if (!connector->polled && I915_HAS_HOTPLUG(dev) && intel_connector->encoder->hpd_pin > HPD_NONE)
+                if (connector->encoder && !connector->polled && I915_HAS_HOTPLUG(dev) && intel_connector->encoder->hpd_pin > HPD_NONE)
+                        connector->polled = DRM_CONNECTOR_POLL_HPD;
+                if (intel_connector->mst_port)
                         connector->polled = DRM_CONNECTOR_POLL_HPD;
         }
 
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 1aec4257e296..9b1542f1cf01 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -116,7 +116,10 @@ enum port intel_ddi_get_encoder_port(struct intel_encoder *intel_encoder)
         struct drm_encoder *encoder = &intel_encoder->base;
         int type = intel_encoder->type;
 
-        if (type == INTEL_OUTPUT_DISPLAYPORT || type == INTEL_OUTPUT_EDP ||
+        if (type == INTEL_OUTPUT_DP_MST) {
+                struct intel_digital_port *intel_dig_port = enc_to_mst(encoder)->primary;
+                return intel_dig_port->port;
+        } else if (type == INTEL_OUTPUT_DISPLAYPORT || type == INTEL_OUTPUT_EDP ||
             type == INTEL_OUTPUT_HDMI || type == INTEL_OUTPUT_UNKNOWN) {
                 struct intel_digital_port *intel_dig_port =
                         enc_to_dig_port(encoder);
@@ -584,8 +587,8 @@ static int intel_ddi_calc_wrpll_link(struct drm_i915_private *dev_priv,
         return (refclk * n * 100) / (p * r);
 }
 
-static void intel_ddi_clock_get(struct intel_encoder *encoder,
-                                struct intel_crtc_config *pipe_config)
+void intel_ddi_clock_get(struct intel_encoder *encoder,
+                         struct intel_crtc_config *pipe_config)
 {
         struct drm_i915_private *dev_priv = encoder->base.dev->dev_private;
         int link_clock = 0;
@@ -755,8 +758,7 @@ void intel_ddi_set_pipe_settings(struct drm_crtc *crtc)
         int type = intel_encoder->type;
         uint32_t temp;
 
-        if (type == INTEL_OUTPUT_DISPLAYPORT || type == INTEL_OUTPUT_EDP) {
-
+        if (type == INTEL_OUTPUT_DISPLAYPORT || type == INTEL_OUTPUT_EDP || type == INTEL_OUTPUT_DP_MST) {
                 temp = TRANS_MSA_SYNC_CLK;
                 switch (intel_crtc->config.pipe_bpp) {
                 case 18:
@@ -778,6 +780,21 @@ void intel_ddi_set_pipe_settings(struct drm_crtc *crtc)
         }
 }
 
+void intel_ddi_set_vc_payload_alloc(struct drm_crtc *crtc, bool state)
+{
+        struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+        struct drm_device *dev = crtc->dev;
+        struct drm_i915_private *dev_priv = dev->dev_private;
+        enum transcoder cpu_transcoder = intel_crtc->config.cpu_transcoder;
+        uint32_t temp;
+        temp = I915_READ(TRANS_DDI_FUNC_CTL(cpu_transcoder));
+        if (state == true)
+                temp |= TRANS_DDI_DP_VC_PAYLOAD_ALLOC;
+        else
+                temp &= ~TRANS_DDI_DP_VC_PAYLOAD_ALLOC;
+        I915_WRITE(TRANS_DDI_FUNC_CTL(cpu_transcoder), temp);
+}
+
 void intel_ddi_enable_transcoder_func(struct drm_crtc *crtc)
 {
         struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
@@ -857,7 +874,19 @@ void intel_ddi_enable_transcoder_func(struct drm_crtc *crtc)
                    type == INTEL_OUTPUT_EDP) {
                 struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
 
-                temp |= TRANS_DDI_MODE_SELECT_DP_SST;
+                if (intel_dp->is_mst) {
+                        temp |= TRANS_DDI_MODE_SELECT_DP_MST;
+                } else
+                        temp |= TRANS_DDI_MODE_SELECT_DP_SST;
+
+                temp |= DDI_PORT_WIDTH(intel_dp->lane_count);
+        } else if (type == INTEL_OUTPUT_DP_MST) {
+                struct intel_dp *intel_dp = &enc_to_mst(encoder)->primary->dp;
+
+                if (intel_dp->is_mst) {
+                        temp |= TRANS_DDI_MODE_SELECT_DP_MST;
+                } else
+                        temp |= TRANS_DDI_MODE_SELECT_DP_SST;
 
                 temp |= DDI_PORT_WIDTH(intel_dp->lane_count);
         } else {
@@ -874,7 +903,7 @@ void intel_ddi_disable_transcoder_func(struct drm_i915_private *dev_priv,
         uint32_t reg = TRANS_DDI_FUNC_CTL(cpu_transcoder);
         uint32_t val = I915_READ(reg);
 
-        val &= ~(TRANS_DDI_FUNC_ENABLE | TRANS_DDI_PORT_MASK);
+        val &= ~(TRANS_DDI_FUNC_ENABLE | TRANS_DDI_PORT_MASK | TRANS_DDI_DP_VC_PAYLOAD_ALLOC);
         val |= TRANS_DDI_PORT_NONE;
         I915_WRITE(reg, val);
 }
@@ -913,8 +942,11 @@ bool intel_ddi_connector_get_hw_state(struct intel_connector *intel_connector)
         case TRANS_DDI_MODE_SELECT_DP_SST:
                 if (type == DRM_MODE_CONNECTOR_eDP)
                         return true;
-        case TRANS_DDI_MODE_SELECT_DP_MST:
                 return (type == DRM_MODE_CONNECTOR_DisplayPort);
+        case TRANS_DDI_MODE_SELECT_DP_MST:
+                /* if the transcoder is in MST state then
+                 * connector isn't connected */
+                return false;
 
         case TRANS_DDI_MODE_SELECT_FDI:
                 return (type == DRM_MODE_CONNECTOR_VGA);
@@ -966,6 +998,9 @@ bool intel_ddi_get_hw_state(struct intel_encoder *encoder,
 
                         if ((tmp & TRANS_DDI_PORT_MASK)
                             == TRANS_DDI_SELECT_PORT(port)) {
+                                if ((tmp & TRANS_DDI_MODE_SELECT_MASK) == TRANS_DDI_MODE_SELECT_DP_MST)
+                                        return false;
+
                                 *pipe = i;
                                 return true;
                         }
@@ -1272,10 +1307,15 @@ void intel_ddi_prepare_link_retrain(struct drm_encoder *encoder)
                         intel_wait_ddi_buf_idle(dev_priv, port);
         }
 
-        val = DP_TP_CTL_ENABLE | DP_TP_CTL_MODE_SST |
+        val = DP_TP_CTL_ENABLE |
               DP_TP_CTL_LINK_TRAIN_PAT1 | DP_TP_CTL_SCRAMBLE_DISABLE;
-        if (drm_dp_enhanced_frame_cap(intel_dp->dpcd))
-                val |= DP_TP_CTL_ENHANCED_FRAME_ENABLE;
+        if (intel_dp->is_mst)
+                val |= DP_TP_CTL_MODE_MST;
+        else {
+                val |= DP_TP_CTL_MODE_SST;
+                if (drm_dp_enhanced_frame_cap(intel_dp->dpcd))
+                        val |= DP_TP_CTL_ENHANCED_FRAME_ENABLE;
+        }
         I915_WRITE(DP_TP_CTL(port), val);
         POSTING_READ(DP_TP_CTL(port));
 
@@ -1314,11 +1354,16 @@ void intel_ddi_fdi_disable(struct drm_crtc *crtc)
 
 static void intel_ddi_hot_plug(struct intel_encoder *intel_encoder)
 {
-        struct intel_dp *intel_dp = enc_to_intel_dp(&intel_encoder->base);
-        int type = intel_encoder->type;
+        struct intel_digital_port *intel_dig_port = enc_to_dig_port(&intel_encoder->base);
+        int type = intel_dig_port->base.type;
+
+        if (type != INTEL_OUTPUT_DISPLAYPORT &&
+            type != INTEL_OUTPUT_EDP &&
+            type != INTEL_OUTPUT_UNKNOWN) {
+                return;
+        }
 
-        if (type == INTEL_OUTPUT_DISPLAYPORT || type == INTEL_OUTPUT_EDP)
-                intel_dp_check_link_status(intel_dp);
+        intel_dp_hot_plug(intel_encoder);
 }
 
 void intel_ddi_get_config(struct intel_encoder *encoder,
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 421ea71b2e58..7b542b477a4e 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -101,6 +101,14 @@ static void haswell_set_pipeconf(struct drm_crtc *crtc);
 static void intel_set_pipe_csc(struct drm_crtc *crtc);
 static void vlv_prepare_pll(struct intel_crtc *crtc);
 
+static struct intel_encoder *intel_find_encoder(struct intel_connector *connector, int pipe)
+{
+        if (!connector->mst_port)
+                return connector->encoder;
+        else
+                return &connector->mst_port->mst_encoders[pipe]->base;
+}
+
 typedef struct {
         int     min, max;
 } intel_range_t;
@@ -4130,6 +4138,9 @@ static void haswell_crtc_enable(struct drm_crtc *crtc)
         if (intel_crtc->config.has_pch_encoder)
                 lpt_pch_enable(crtc);
 
+        if (intel_crtc->config.dp_encoder_is_mst)
+                intel_ddi_set_vc_payload_alloc(crtc, true);
+
         for_each_encoder_on_crtc(dev, crtc, encoder) {
                 encoder->enable(encoder);
                 intel_opregion_notify_encoder(encoder, true);
@@ -4178,6 +4189,9 @@ static void ironlake_crtc_disable(struct drm_crtc *crtc)
 
         intel_disable_pipe(dev_priv, pipe);
 
+        if (intel_crtc->config.dp_encoder_is_mst)
+                intel_ddi_set_vc_payload_alloc(crtc, false);
+
         ironlake_pfit_disable(intel_crtc);
 
         for_each_encoder_on_crtc(dev, crtc, encoder)
@@ -4336,6 +4350,9 @@ intel_display_port_power_domain(struct intel_encoder *intel_encoder)
         case INTEL_OUTPUT_EDP:
                 intel_dig_port = enc_to_dig_port(&intel_encoder->base);
                 return port_to_power_domain(intel_dig_port->port);
+        case INTEL_OUTPUT_DP_MST:
+                intel_dig_port = enc_to_mst(&intel_encoder->base)->primary;
+                return port_to_power_domain(intel_dig_port->port);
         case INTEL_OUTPUT_ANALOG:
                 return POWER_DOMAIN_PORT_CRT;
         case INTEL_OUTPUT_DSI:
@@ -5004,6 +5021,10 @@ static void intel_connector_check_state(struct intel_connector *connector)
                               connector->base.base.id,
                               connector->base.name);
 
+                /* there is no real hw state for MST connectors */
+                if (connector->mst_port)
+                        return;
+
                 WARN(connector->base.dpms == DRM_MODE_DPMS_OFF,
                      "wrong connector dpms state\n");
                 WARN(connector->base.encoder != &encoder->base,
@@ -10524,6 +10545,14 @@ check_encoder_state(struct drm_device *dev)
                         if (connector->base.dpms != DRM_MODE_DPMS_OFF)
                                 active = true;
                 }
+                /*
+                 * for MST connectors if we unplug the connector is gone
+                 * away but the encoder is still connected to a crtc
+                 * until a modeset happens in response to the hotplug.
+                 */
+                if (!enabled && encoder->base.encoder_type == DRM_MODE_ENCODER_DPMST)
+                        continue;
+
                 WARN(!!encoder->base.crtc != enabled,
                      "encoder's enabled state mismatch "
                      "(expected %i, found %i)\n",
@@ -11069,7 +11098,7 @@ intel_modeset_stage_output_state(struct drm_device *dev,
                  * for them. */
                 for (ro = 0; ro < set->num_connectors; ro++) {
                         if (set->connectors[ro] == &connector->base) {
-                                connector->new_encoder = connector->encoder;
+                                connector->new_encoder = intel_find_encoder(connector, to_intel_crtc(set->crtc)->pipe);
                                 break;
                         }
                 }
@@ -11115,7 +11144,7 @@ intel_modeset_stage_output_state(struct drm_device *dev,
                                          new_crtc)) {
                         return -EINVAL;
                 }
-                connector->encoder->new_crtc = to_intel_crtc(new_crtc);
+                connector->new_encoder->new_crtc = to_intel_crtc(new_crtc);
 
                 DRM_DEBUG_KMS("[CONNECTOR:%d:%s] to [CRTC:%d]\n",
                         connector->base.base.id,
@@ -11149,7 +11178,12 @@ intel_modeset_stage_output_state(struct drm_device *dev,
                 }
         }
         /* Now we've also updated encoder->new_crtc for all encoders. */
-
+        list_for_each_entry(connector, &dev->mode_config.connector_list,
+                            base.head) {
+                if (connector->new_encoder)
+                        if (connector->new_encoder != connector->encoder)
+                                connector->encoder = connector->new_encoder;
+        }
         for_each_intel_crtc(dev, crtc) {
                 crtc->new_enabled = false;
 
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 30816b3b0742..e7a7953da6d1 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -112,7 +112,7 @@ static void intel_dp_link_down(struct intel_dp *intel_dp);
 static bool _edp_panel_vdd_on(struct intel_dp *intel_dp);
 static void edp_panel_vdd_off(struct intel_dp *intel_dp, bool sync);
 
-static int
+int
 intel_dp_max_link_bw(struct intel_dp *intel_dp)
 {
         int max_link_bw = intel_dp->dpcd[DP_MAX_LINK_RATE];
@@ -740,8 +740,9 @@ intel_dp_connector_unregister(struct intel_connector *intel_connector)
 {
         struct intel_dp *intel_dp = intel_attached_dp(&intel_connector->base);
 
-        sysfs_remove_link(&intel_connector->base.kdev->kobj,
-                          intel_dp->aux.ddc.dev.kobj.name);
+        if (!intel_connector->mst_port)
+                sysfs_remove_link(&intel_connector->base.kdev->kobj,
+                                  intel_dp->aux.ddc.dev.kobj.name);
         intel_connector_unregister(intel_connector);
 }
 
@@ -3309,6 +3310,33 @@ intel_dp_probe_oui(struct intel_dp *intel_dp)
         edp_panel_vdd_off(intel_dp, false);
 }
 
+static bool
+intel_dp_probe_mst(struct intel_dp *intel_dp)
+{
+        u8 buf[1];
+
+        if (!intel_dp->can_mst)
+                return false;
+
+        if (intel_dp->dpcd[DP_DPCD_REV] < 0x12)
+                return false;
+
+        _edp_panel_vdd_on(intel_dp);
+        if (intel_dp_dpcd_read_wake(&intel_dp->aux, DP_MSTM_CAP, buf, 1)) {
+                if (buf[0] & DP_MST_CAP) {
+                        DRM_DEBUG_KMS("Sink is MST capable\n");
+                        intel_dp->is_mst = true;
+                } else {
+                        DRM_DEBUG_KMS("Sink is not MST capable\n");
+                        intel_dp->is_mst = false;
+                }
+        }
+        edp_panel_vdd_off(intel_dp, false);
+
+        drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst_mgr, intel_dp->is_mst);
+        return intel_dp->is_mst;
+}
+
 int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc)
 {
         struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
@@ -3346,6 +3374,20 @@ intel_dp_get_sink_irq(struct intel_dp *intel_dp, u8 *sink_irq_vector)
                                        sink_irq_vector, 1) == 1;
 }
 
+static bool
+intel_dp_get_sink_irq_esi(struct intel_dp *intel_dp, u8 *sink_irq_vector)
+{
+        int ret;
+
+        ret = intel_dp_dpcd_read_wake(&intel_dp->aux,
+                                             DP_SINK_COUNT_ESI,
+                                             sink_irq_vector, 14);
+        if (ret != 14)
+                return false;
+
+        return true;
+}
+
 static void
 intel_dp_handle_test_request(struct intel_dp *intel_dp)
 {
@@ -3353,6 +3395,63 @@ intel_dp_handle_test_request(struct intel_dp *intel_dp)
         drm_dp_dpcd_writeb(&intel_dp->aux, DP_TEST_RESPONSE, DP_TEST_NAK);
 }
 
+static int
+intel_dp_check_mst_status(struct intel_dp *intel_dp)
+{
+        bool bret;
+
+        if (intel_dp->is_mst) {
+                u8 esi[16] = { 0 };
+                int ret = 0;
+                int retry;
+                bool handled;
+                bret = intel_dp_get_sink_irq_esi(intel_dp, esi);
+go_again:
+                if (bret == true) {
+
+                        /* check link status - esi[10] = 0x200c */
+                        if (intel_dp->active_mst_links && !drm_dp_channel_eq_ok(&esi[10], intel_dp->lane_count)) {
+                                DRM_DEBUG_KMS("channel EQ not ok, retraining\n");
+                                intel_dp_start_link_train(intel_dp);
+                                intel_dp_complete_link_train(intel_dp);
+                                intel_dp_stop_link_train(intel_dp);
+                        }
+
+                        DRM_DEBUG_KMS("got esi %02x %02x %02x\n", esi[0], esi[1], esi[2]);
+                        ret = drm_dp_mst_hpd_irq(&intel_dp->mst_mgr, esi, &handled);
+
+                        if (handled) {
+                                for (retry = 0; retry < 3; retry++) {
+                                        int wret;
+                                        wret = drm_dp_dpcd_write(&intel_dp->aux,
+                                                                 DP_SINK_COUNT_ESI+1,
+                                                                 &esi[1], 3);
+                                        if (wret == 3) {
+                                                break;
+                                        }
+                                }
+
+                                bret = intel_dp_get_sink_irq_esi(intel_dp, esi);
+                                if (bret == true) {
+                                        DRM_DEBUG_KMS("got esi2 %02x %02x %02x\n", esi[0], esi[1], esi[2]);
+                                        goto go_again;
+                                }
+                        } else
+                                ret = 0;
+
+                        return ret;
+                } else {
+                        struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
+                        DRM_DEBUG_KMS("failed to get ESI - device may have failed\n");
+                        intel_dp->is_mst = false;
+                        drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst_mgr, intel_dp->is_mst);
+                        /* send a hotplug event */
+                        drm_kms_helper_hotplug_event(intel_dig_port->base.base.dev);
+                }
+        }
+        return -EINVAL;
+}
+
 /*
  * According to DP spec
  * 5.1.2:
@@ -3361,7 +3460,6 @@ intel_dp_handle_test_request(struct intel_dp *intel_dp)
  *  3. Use Link Training from 2.5.3.3 and 3.5.1.3
  *  4. Check link status on receipt of hot-plug interrupt
  */
-
 void
 intel_dp_check_link_status(struct intel_dp *intel_dp)
 {
@@ -3581,6 +3679,7 @@ intel_dp_detect(struct drm_connector *connector, bool force)
         enum drm_connector_status status;
         enum intel_display_power_domain power_domain;
         struct edid *edid = NULL;
+        bool ret;
 
         intel_runtime_pm_get(dev_priv);
 
@@ -3590,6 +3689,14 @@ intel_dp_detect(struct drm_connector *connector, bool force)
         DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n",
                       connector->base.id, connector->name);
 
+        if (intel_dp->is_mst) {
+                /* MST devices are disconnected from a monitor POV */
+                if (intel_encoder->type != INTEL_OUTPUT_EDP)
+                        intel_encoder->type = INTEL_OUTPUT_DISPLAYPORT;
+                status = connector_status_disconnected;
+                goto out;
+        }
+
         intel_dp->has_audio = false;
 
         if (HAS_PCH_SPLIT(dev))
@@ -3602,6 +3709,16 @@ intel_dp_detect(struct drm_connector *connector, bool force)
 
         intel_dp_probe_oui(intel_dp);
 
+        ret = intel_dp_probe_mst(intel_dp);
+        if (ret) {
+                /* if we are in MST mode then this connector
+                   won't appear connected or have anything with EDID on it */
+                if (intel_encoder->type != INTEL_OUTPUT_EDP)
+                        intel_encoder->type = INTEL_OUTPUT_DISPLAYPORT;
+                status = connector_status_disconnected;
+                goto out;
+        }
+
         if (intel_dp->force_audio != HDMI_AUDIO_AUTO) {
                 intel_dp->has_audio = (intel_dp->force_audio == HDMI_AUDIO_ON);
         } else {
@@ -3797,6 +3914,7 @@ void intel_dp_encoder_destroy(struct drm_encoder *encoder)
         struct drm_device *dev = intel_dp_to_dev(intel_dp);
 
         drm_dp_aux_unregister(&intel_dp->aux);
+        intel_dp_mst_encoder_cleanup(intel_dig_port);
         drm_encoder_cleanup(encoder);
         if (is_edp(intel_dp)) {
                 cancel_delayed_work_sync(&intel_dp->panel_vdd_work);
@@ -3825,28 +3943,62 @@ static const struct drm_encoder_funcs intel_dp_enc_funcs = {
         .destroy = intel_dp_encoder_destroy,
 };
 
-static void
+void
 intel_dp_hot_plug(struct intel_encoder *intel_encoder)
 {
-        struct intel_dp *intel_dp = enc_to_intel_dp(&intel_encoder->base);
-
-        intel_dp_check_link_status(intel_dp);
+        return;
 }
 
 bool
 intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
 {
         struct intel_dp *intel_dp = &intel_dig_port->dp;
+        struct drm_device *dev = intel_dig_port->base.base.dev;
+        struct drm_i915_private *dev_priv = dev->dev_private;
+        int ret;
+        if (intel_dig_port->base.type != INTEL_OUTPUT_EDP)
+                intel_dig_port->base.type = INTEL_OUTPUT_DISPLAYPORT;
 
-        if (long_hpd)
-                return true;
+        DRM_DEBUG_KMS("got hpd irq on port %d - %s\n", intel_dig_port->port,
+                      long_hpd ? "long" : "short");
 
-        /*
-         * we'll check the link status via the normal hot plug path later -
-         * but for short hpds we should check it now
-         */
-        intel_dp_check_link_status(intel_dp);
+        if (long_hpd) {
+                if (!ibx_digital_port_connected(dev_priv, intel_dig_port))
+                        goto mst_fail;
+
+                if (!intel_dp_get_dpcd(intel_dp)) {
+                        goto mst_fail;
+                }
+
+                intel_dp_probe_oui(intel_dp);
+
+                if (!intel_dp_probe_mst(intel_dp))
+                        goto mst_fail;
+
+        } else {
+                if (intel_dp->is_mst) {
+                        ret = intel_dp_check_mst_status(intel_dp);
+                        if (ret == -EINVAL)
+                                goto mst_fail;
+                }
+
+                if (!intel_dp->is_mst) {
+                        /*
+                         * we'll check the link status via the normal hot plug path later -
+                         * but for short hpds we should check it now
+                         */
+                        intel_dp_check_link_status(intel_dp);
+                }
+        }
         return false;
+mst_fail:
+        /* if we were in MST mode, and device is not there get out of MST mode */
+        if (intel_dp->is_mst) {
+                DRM_DEBUG_KMS("MST device may have disappeared %d vs %d\n", intel_dp->is_mst, intel_dp->mst_mgr.mst_state);
+                intel_dp->is_mst = false;
+                drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst_mgr, intel_dp->is_mst);
+        }
+        return true;
 }
 
 /* Return which DP Port should be selected for Transcoder DP control */
@@ -3897,7 +4049,7 @@ bool intel_dp_is_edp(struct drm_device *dev, enum port port)
         return false;
 }
 
-static void
+void
 intel_dp_add_properties(struct intel_dp *intel_dp, struct drm_connector *connector)
 {
         struct intel_connector *intel_connector = to_intel_connector(connector);
@@ -4391,6 +4543,13 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
 
         intel_dp_aux_init(intel_dp, intel_connector);
 
+        /* init MST on ports that can support it */
+        if (IS_HASWELL(dev) || IS_BROADWELL(dev)) {
+                if (port == PORT_B || port == PORT_C || port == PORT_D) {
+                        intel_dp_mst_encoder_init(intel_dig_port, intel_connector->base.base.id);
+                }
+        }
+
         if (!intel_edp_init_connector(intel_dp, intel_connector, &power_seq)) {
                 drm_dp_aux_unregister(&intel_dp->aux);
                 if (is_edp(intel_dp)) {
@@ -4487,3 +4646,46 @@ intel_dp_init(struct drm_device *dev, int output_reg, enum port port)
                 kfree(intel_connector);
         }
 }
+
+void intel_dp_mst_suspend(struct drm_device *dev)
+{
+        struct drm_i915_private *dev_priv = dev->dev_private;
+        int i;
+
+        /* disable MST */
+        for (i = 0; i < I915_MAX_PORTS; i++) {
+                struct intel_digital_port *intel_dig_port = dev_priv->hpd_irq_port[i];
+                if (!intel_dig_port)
+                        continue;
+
+                if (intel_dig_port->base.type == INTEL_OUTPUT_DISPLAYPORT) {
+                        if (!intel_dig_port->dp.can_mst)
+                                continue;
+                        if (intel_dig_port->dp.is_mst)
+                                drm_dp_mst_topology_mgr_suspend(&intel_dig_port->dp.mst_mgr);
+                }
+        }
+}
+
+void intel_dp_mst_resume(struct drm_device *dev)
+{
+        struct drm_i915_private *dev_priv = dev->dev_private;
+        int i;
+
+        for (i = 0; i < I915_MAX_PORTS; i++) {
+                struct intel_digital_port *intel_dig_port = dev_priv->hpd_irq_port[i];
+                if (!intel_dig_port)
+                        continue;
+                if (intel_dig_port->base.type == INTEL_OUTPUT_DISPLAYPORT) {
+                        int ret;
+
+                        if (!intel_dig_port->dp.can_mst)
+                                continue;
+
+                        ret = drm_dp_mst_topology_mgr_resume(&intel_dig_port->dp.mst_mgr);
+                        if (ret != 0) {
+                                intel_dp_check_mst_status(&intel_dig_port->dp);
+                        }
+                }
+        }
+}
diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
new file mode 100644
index 000000000000..ec48d562c7fc
--- /dev/null
+++ b/drivers/gpu/drm/i915/intel_dp_mst.c
@@ -0,0 +1,534 @@
+/*
+ * Copyright © 2008 Intel Corporation
+ *             2014 Red Hat Inc.
+ *
+ * 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 <drm/drmP.h>
+#include "i915_drv.h"
+#include "intel_drv.h"
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_edid.h>
+
+static bool intel_dp_mst_compute_config(struct intel_encoder *encoder,
+                                        struct intel_crtc_config *pipe_config)
+{
+        struct intel_dp_mst_encoder *intel_mst = enc_to_mst(&encoder->base);
+        struct intel_digital_port *intel_dig_port = intel_mst->primary;
+        struct intel_dp *intel_dp = &intel_dig_port->dp;
+        struct drm_device *dev = encoder->base.dev;
+        int bpp;
+        int lane_count, slots;
+        struct drm_display_mode *adjusted_mode = &pipe_config->adjusted_mode;
+        struct intel_connector *found = NULL, *intel_connector;
+        int mst_pbn;
+
+        pipe_config->dp_encoder_is_mst = true;
+        pipe_config->has_pch_encoder = false;
+        pipe_config->has_dp_encoder = true;
+        bpp = 24;
+        /*
+         * for MST we always configure max link bw - the spec doesn't
+         * seem to suggest we should do otherwise.
+         */
+        lane_count = drm_dp_max_lane_count(intel_dp->dpcd);
+        intel_dp->link_bw = intel_dp_max_link_bw(intel_dp);
+        intel_dp->lane_count = lane_count;
+
+        pipe_config->pipe_bpp = 24;
+        pipe_config->port_clock = drm_dp_bw_code_to_link_rate(intel_dp->link_bw);
+
+        list_for_each_entry(intel_connector, &dev->mode_config.connector_list, base.head) {
+                if (intel_connector->new_encoder == encoder) {
+                        found = intel_connector;
+                        break;
+                }
+        }
+
+        if (!found) {
+                DRM_ERROR("can't find connector\n");
+                return false;
+        }
+
+        mst_pbn = drm_dp_calc_pbn_mode(adjusted_mode->clock, bpp);
+
+        pipe_config->pbn = mst_pbn;
+        slots = drm_dp_find_vcpi_slots(&intel_dp->mst_mgr, mst_pbn);
+
+        intel_link_compute_m_n(bpp, lane_count,
+                               adjusted_mode->crtc_clock,
+                               pipe_config->port_clock,
+                               &pipe_config->dp_m_n);
+
+        pipe_config->dp_m_n.tu = slots;
+        return true;
+
+}
+
+static void intel_mst_disable_dp(struct intel_encoder *encoder)
+{
+        struct intel_dp_mst_encoder *intel_mst = enc_to_mst(&encoder->base);
+        struct intel_digital_port *intel_dig_port = intel_mst->primary;
+        struct intel_dp *intel_dp = &intel_dig_port->dp;
+        int ret;
+
+        DRM_DEBUG_KMS("%d\n", intel_dp->active_mst_links);
+
+        drm_dp_mst_reset_vcpi_slots(&intel_dp->mst_mgr, intel_mst->port);
+
+        ret = drm_dp_update_payload_part1(&intel_dp->mst_mgr);
+        if (ret) {
+                DRM_ERROR("failed to update payload %d\n", ret);
+        }
+}
+
+static void intel_mst_post_disable_dp(struct intel_encoder *encoder)
+{
+        struct intel_dp_mst_encoder *intel_mst = enc_to_mst(&encoder->base);
+        struct intel_digital_port *intel_dig_port = intel_mst->primary;
+        struct intel_dp *intel_dp = &intel_dig_port->dp;
+
+        DRM_DEBUG_KMS("%d\n", intel_dp->active_mst_links);
+
+        /* this can fail */
+        drm_dp_check_act_status(&intel_dp->mst_mgr);
+        /* and this can also fail */
+        drm_dp_update_payload_part2(&intel_dp->mst_mgr);
+
+        drm_dp_mst_deallocate_vcpi(&intel_dp->mst_mgr, intel_mst->port);
+
+        intel_dp->active_mst_links--;
+        intel_mst->port = NULL;
+        if (intel_dp->active_mst_links == 0) {
+                intel_dig_port->base.post_disable(&intel_dig_port->base);
+                intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
+        }
+}
+
+static void intel_mst_pre_enable_dp(struct intel_encoder *encoder)
+{
+        struct intel_dp_mst_encoder *intel_mst = enc_to_mst(&encoder->base);
+        struct intel_digital_port *intel_dig_port = intel_mst->primary;
+        struct intel_dp *intel_dp = &intel_dig_port->dp;
+        struct drm_device *dev = encoder->base.dev;
+        struct drm_i915_private *dev_priv = dev->dev_private;
+        enum port port = intel_dig_port->port;
+        int ret;
+        uint32_t temp;
+        struct intel_connector *found = NULL, *intel_connector;
+        int slots;
+        struct drm_crtc *crtc = encoder->base.crtc;
+        struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+
+        list_for_each_entry(intel_connector, &dev->mode_config.connector_list, base.head) {
+                if (intel_connector->new_encoder == encoder) {
+                        found = intel_connector;
+                        break;
+                }
+        }
+
+        if (!found) {
+                DRM_ERROR("can't find connector\n");
+                return;
+        }
+
+        DRM_DEBUG_KMS("%d\n", intel_dp->active_mst_links);
+        intel_mst->port = found->port;
+
+        if (intel_dp->active_mst_links == 0) {
+                enum port port = intel_ddi_get_encoder_port(encoder);
+
+                I915_WRITE(PORT_CLK_SEL(port), intel_crtc->config.ddi_pll_sel);
+
+                intel_ddi_init_dp_buf_reg(&intel_dig_port->base);
+
+                intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
+
+
+                intel_dp_start_link_train(intel_dp);
+                intel_dp_complete_link_train(intel_dp);
+                intel_dp_stop_link_train(intel_dp);
+        }
+
+        ret = drm_dp_mst_allocate_vcpi(&intel_dp->mst_mgr,
+                                       intel_mst->port, intel_crtc->config.pbn, &slots);
+        if (ret == false) {
+                DRM_ERROR("failed to allocate vcpi\n");
+                return;
+        }
+
+
+        intel_dp->active_mst_links++;
+        temp = I915_READ(DP_TP_STATUS(port));
+        I915_WRITE(DP_TP_STATUS(port), temp);
+
+        ret = drm_dp_update_payload_part1(&intel_dp->mst_mgr);
+}
+
+static void intel_mst_enable_dp(struct intel_encoder *encoder)
+{
+        struct intel_dp_mst_encoder *intel_mst = enc_to_mst(&encoder->base);
+        struct intel_digital_port *intel_dig_port = intel_mst->primary;
+        struct intel_dp *intel_dp = &intel_dig_port->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;
+        int ret;
+
+        DRM_DEBUG_KMS("%d\n", intel_dp->active_mst_links);
+
+        if (wait_for((I915_READ(DP_TP_STATUS(port)) & DP_TP_STATUS_ACT_SENT),
+                     1))
+                DRM_ERROR("Timed out waiting for ACT sent\n");
+
+        ret = drm_dp_check_act_status(&intel_dp->mst_mgr);
+
+        ret = drm_dp_update_payload_part2(&intel_dp->mst_mgr);
+}
+
+static bool intel_dp_mst_enc_get_hw_state(struct intel_encoder *encoder,
+                                      enum pipe *pipe)
+{
+        struct intel_dp_mst_encoder *intel_mst = enc_to_mst(&encoder->base);
+        *pipe = intel_mst->pipe;
+        if (intel_mst->port)
+                return true;
+        return false;
+}
+
+static void intel_dp_mst_enc_get_config(struct intel_encoder *encoder,
+                                        struct intel_crtc_config *pipe_config)
+{
+        struct intel_dp_mst_encoder *intel_mst = enc_to_mst(&encoder->base);
+        struct intel_digital_port *intel_dig_port = intel_mst->primary;
+        struct intel_crtc *crtc = to_intel_crtc(encoder->base.crtc);
+        struct drm_device *dev = encoder->base.dev;
+        struct drm_i915_private *dev_priv = dev->dev_private;
+        enum transcoder cpu_transcoder = crtc->config.cpu_transcoder;
+        u32 temp, flags = 0;
+
+        pipe_config->has_dp_encoder = true;
+
+        temp = I915_READ(TRANS_DDI_FUNC_CTL(cpu_transcoder));
+        if (temp & TRANS_DDI_PHSYNC)
+                flags |= DRM_MODE_FLAG_PHSYNC;
+        else
+                flags |= DRM_MODE_FLAG_NHSYNC;
+        if (temp & TRANS_DDI_PVSYNC)
+                flags |= DRM_MODE_FLAG_PVSYNC;
+        else
+                flags |= DRM_MODE_FLAG_NVSYNC;
+
+        switch (temp & TRANS_DDI_BPC_MASK) {
+        case TRANS_DDI_BPC_6:
+                pipe_config->pipe_bpp = 18;
+                break;
+        case TRANS_DDI_BPC_8:
+                pipe_config->pipe_bpp = 24;
+                break;
+        case TRANS_DDI_BPC_10:
+                pipe_config->pipe_bpp = 30;
+                break;
+        case TRANS_DDI_BPC_12:
+                pipe_config->pipe_bpp = 36;
+                break;
+        default:
+                break;
+        }
+        pipe_config->adjusted_mode.flags |= flags;
+        intel_dp_get_m_n(crtc, pipe_config);
+
+        intel_ddi_clock_get(&intel_dig_port->base, pipe_config);
+}
+
+static int intel_dp_mst_get_ddc_modes(struct drm_connector *connector)
+{
+        struct intel_connector *intel_connector = to_intel_connector(connector);
+        struct intel_dp *intel_dp = intel_connector->mst_port;
+        struct edid *edid;
+        int ret;
+
+        edid = drm_dp_mst_get_edid(connector, &intel_dp->mst_mgr, intel_connector->port);
+        if (!edid)
+                return 0;
+
+        ret = intel_connector_update_modes(connector, edid);
+        kfree(edid);
+
+        return ret;
+}
+
+static enum drm_connector_status
+intel_mst_port_dp_detect(struct drm_connector *connector)
+{
+        struct intel_connector *intel_connector = to_intel_connector(connector);
+        struct intel_dp *intel_dp = intel_connector->mst_port;
+
+        return drm_dp_mst_detect_port(&intel_dp->mst_mgr, intel_connector->port);
+}
+
+static enum drm_connector_status
+intel_dp_mst_detect(struct drm_connector *connector, bool force)
+{
+        enum drm_connector_status status;
+        status = intel_mst_port_dp_detect(connector);
+        return status;
+}
+
+static int
+intel_dp_mst_set_property(struct drm_connector *connector,
+                          struct drm_property *property,
+                          uint64_t val)
+{
+        return 0;
+}
+
+static void
+intel_dp_mst_connector_destroy(struct drm_connector *connector)
+{
+        struct intel_connector *intel_connector = to_intel_connector(connector);
+
+        if (!IS_ERR_OR_NULL(intel_connector->edid))
+                kfree(intel_connector->edid);
+
+        drm_connector_cleanup(connector);
+        kfree(connector);
+}
+
+static const struct drm_connector_funcs intel_dp_mst_connector_funcs = {
+        .dpms = intel_connector_dpms,
+        .detect = intel_dp_mst_detect,
+        .fill_modes = drm_helper_probe_single_connector_modes,
+        .set_property = intel_dp_mst_set_property,
+        .destroy = intel_dp_mst_connector_destroy,
+};
+
+static int intel_dp_mst_get_modes(struct drm_connector *connector)
+{
+        return intel_dp_mst_get_ddc_modes(connector);
+}
+
+static enum drm_mode_status
+intel_dp_mst_mode_valid(struct drm_connector *connector,
+                        struct drm_display_mode *mode)
+{
+        /* TODO - validate mode against available PBN for link */
+        if (mode->clock < 10000)
+                return MODE_CLOCK_LOW;
+
+        if (mode->flags & DRM_MODE_FLAG_DBLCLK)
+                return MODE_H_ILLEGAL;
+
+        return MODE_OK;
+}
+
+static struct drm_encoder *intel_mst_best_encoder(struct drm_connector *connector)
+{
+        struct intel_connector *intel_connector = to_intel_connector(connector);
+        struct intel_dp *intel_dp = intel_connector->mst_port;
+        return &intel_dp->mst_encoders[0]->base.base;
+}
+
+static const struct drm_connector_helper_funcs intel_dp_mst_connector_helper_funcs = {
+        .get_modes = intel_dp_mst_get_modes,
+        .mode_valid = intel_dp_mst_mode_valid,
+        .best_encoder = intel_mst_best_encoder,
+};
+
+static void intel_dp_mst_encoder_destroy(struct drm_encoder *encoder)
+{
+        struct intel_dp_mst_encoder *intel_mst = enc_to_mst(encoder);
+
+        drm_encoder_cleanup(encoder);
+        kfree(intel_mst);
+}
+
+static const struct drm_encoder_funcs intel_dp_mst_enc_funcs = {
+        .destroy = intel_dp_mst_encoder_destroy,
+};
+
+static bool intel_dp_mst_get_hw_state(struct intel_connector *connector)
+{
+        if (connector->encoder) {
+                enum pipe pipe;
+                if (!connector->encoder->get_hw_state(connector->encoder, &pipe))
+                        return false;
+                return true;
+        }
+        return false;
+}
+
+static struct drm_connector *intel_dp_add_mst_connector(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port, char *pathprop)
+{
+        struct intel_dp *intel_dp = container_of(mgr, struct intel_dp, mst_mgr);
+        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;
+        struct intel_connector *intel_connector;
+        struct drm_connector *connector;
+        int i;
+
+        intel_connector = kzalloc(sizeof(*intel_connector), GFP_KERNEL);
+        if (!intel_connector)
+                return NULL;
+
+        connector = &intel_connector->base;
+        drm_connector_init(dev, connector, &intel_dp_mst_connector_funcs, DRM_MODE_CONNECTOR_DisplayPort);
+        drm_connector_helper_add(connector, &intel_dp_mst_connector_helper_funcs);
+
+        intel_connector->unregister = intel_connector_unregister;
+        intel_connector->get_hw_state = intel_dp_mst_get_hw_state;
+        intel_connector->mst_port = intel_dp;
+        intel_connector->port = port;
+
+        for (i = PIPE_A; i <= PIPE_C; i++) {
+                drm_mode_connector_attach_encoder(&intel_connector->base,
+                                                  &intel_dp->mst_encoders[i]->base.base);
+        }
+        intel_dp_add_properties(intel_dp, connector);
+
+        drm_object_attach_property(&connector->base, dev->mode_config.path_property, 0);
+        drm_mode_connector_set_path_property(connector, pathprop);
+        drm_reinit_primary_mode_group(dev);
+        mutex_lock(&dev->mode_config.mutex);
+        drm_fb_helper_add_one_connector(&dev_priv->fbdev->helper, connector);
+        mutex_unlock(&dev->mode_config.mutex);
+        drm_connector_register(&intel_connector->base);
+        return connector;
+}
+
+static void intel_dp_destroy_mst_connector(struct drm_dp_mst_topology_mgr *mgr,
+                                           struct drm_connector *connector)
+{
+        struct intel_connector *intel_connector = to_intel_connector(connector);
+        struct drm_device *dev = connector->dev;
+        struct drm_i915_private *dev_priv = dev->dev_private;
+        /* need to nuke the connector */
+        mutex_lock(&dev->mode_config.mutex);
+        intel_connector_dpms(connector, DRM_MODE_DPMS_OFF);
+        mutex_unlock(&dev->mode_config.mutex);
+
+        intel_connector->unregister(intel_connector);
+
+        mutex_lock(&dev->mode_config.mutex);
+        drm_fb_helper_remove_one_connector(&dev_priv->fbdev->helper, connector);
+        drm_connector_cleanup(connector);
+        mutex_unlock(&dev->mode_config.mutex);
+
+        drm_reinit_primary_mode_group(dev);
+
+        kfree(intel_connector);
+        DRM_DEBUG_KMS("\n");
+}
+
+static void intel_dp_mst_hotplug(struct drm_dp_mst_topology_mgr *mgr)
+{
+        struct intel_dp *intel_dp = container_of(mgr, struct intel_dp, mst_mgr);
+        struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
+        struct drm_device *dev = intel_dig_port->base.base.dev;
+
+        drm_kms_helper_hotplug_event(dev);
+}
+
+static struct drm_dp_mst_topology_cbs mst_cbs = {
+        .add_connector = intel_dp_add_mst_connector,
+        .destroy_connector = intel_dp_destroy_mst_connector,
+        .hotplug = intel_dp_mst_hotplug,
+};
+
+static struct intel_dp_mst_encoder *
+intel_dp_create_fake_mst_encoder(struct intel_digital_port *intel_dig_port, enum pipe pipe)
+{
+        struct intel_dp_mst_encoder *intel_mst;
+        struct intel_encoder *intel_encoder;
+        struct drm_device *dev = intel_dig_port->base.base.dev;
+
+        intel_mst = kzalloc(sizeof(*intel_mst), GFP_KERNEL);
+
+        if (!intel_mst)
+                return NULL;
+
+        intel_mst->pipe = pipe;
+        intel_encoder = &intel_mst->base;
+        intel_mst->primary = intel_dig_port;
+
+        drm_encoder_init(dev, &intel_encoder->base, &intel_dp_mst_enc_funcs,
+                         DRM_MODE_ENCODER_DPMST);
+
+        intel_encoder->type = INTEL_OUTPUT_DP_MST;
+        intel_encoder->crtc_mask = 0x7;
+        intel_encoder->cloneable = 0;
+
+        intel_encoder->compute_config = intel_dp_mst_compute_config;
+        intel_encoder->disable = intel_mst_disable_dp;
+        intel_encoder->post_disable = intel_mst_post_disable_dp;
+        intel_encoder->pre_enable = intel_mst_pre_enable_dp;
+        intel_encoder->enable = intel_mst_enable_dp;
+        intel_encoder->get_hw_state = intel_dp_mst_enc_get_hw_state;
+        intel_encoder->get_config = intel_dp_mst_enc_get_config;
+
+        return intel_mst;
+
+}
+
+static bool
+intel_dp_create_fake_mst_encoders(struct intel_digital_port *intel_dig_port)
+{
+        int i;
+        struct intel_dp *intel_dp = &intel_dig_port->dp;
+
+        for (i = PIPE_A; i <= PIPE_C; i++)
+                intel_dp->mst_encoders[i] = intel_dp_create_fake_mst_encoder(intel_dig_port, i);
+        return true;
+}
+
+int
+intel_dp_mst_encoder_init(struct intel_digital_port *intel_dig_port, int conn_base_id)
+{
+        struct intel_dp *intel_dp = &intel_dig_port->dp;
+        struct drm_device *dev = intel_dig_port->base.base.dev;
+        int ret;
+
+        intel_dp->can_mst = true;
+        intel_dp->mst_mgr.cbs = &mst_cbs;
+
+        /* create encoders */
+        intel_dp_create_fake_mst_encoders(intel_dig_port);
+        ret = drm_dp_mst_topology_mgr_init(&intel_dp->mst_mgr, dev->dev, &intel_dp->aux, 16, 3, conn_base_id);
+        if (ret) {
+                intel_dp->can_mst = false;
+                return ret;
+        }
+        return 0;
+}
+
+void
+intel_dp_mst_encoder_cleanup(struct intel_digital_port *intel_dig_port)
+{
+        struct intel_dp *intel_dp = &intel_dig_port->dp;
+
+        if (!intel_dp->can_mst)
+                return;
+
+        drm_dp_mst_topology_mgr_destroy(&intel_dp->mst_mgr);
+        /* encoders will get killed by normal cleanup */
+}
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 40086e1a4ee3..1dfd1e518551 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -32,7 +32,7 @@
 #include <drm/drm_crtc.h>
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_fb_helper.h>
-#include <drm/drm_dp_helper.h>
+#include <drm/drm_dp_mst_helper.h>
 
 /**
  * _wait_for - magic (register) wait macro
@@ -100,6 +100,7 @@
 #define INTEL_OUTPUT_EDP 8
 #define INTEL_OUTPUT_DSI 9
 #define INTEL_OUTPUT_UNKNOWN 10
+#define INTEL_OUTPUT_DP_MST 11
 
 #define INTEL_DVO_CHIP_NONE 0
 #define INTEL_DVO_CHIP_LVDS 1
@@ -207,6 +208,10 @@ struct intel_connector {
         /* since POLL and HPD connectors may use the same HPD line keep the native
            state of connector->polled in case hotplug storm detection changes it */
         u8 polled;
+
+        void *port; /* store this opaque as its illegal to dereference it */
+
+        struct intel_dp *mst_port;
 };
 
 typedef struct dpll {
@@ -351,6 +356,9 @@ struct intel_crtc_config {
         bool ips_enabled;
 
         bool double_wide;
+
+        bool dp_encoder_is_mst;
+        int pbn;
 };
 
 struct intel_pipe_wm {
@@ -506,6 +514,7 @@ struct intel_hdmi {
                                struct drm_display_mode *adjusted_mode);
 };
 
+struct intel_dp_mst_encoder;
 #define DP_MAX_DOWNSTREAM_PORTS         0x10
 
 /**
@@ -545,8 +554,16 @@ struct intel_dp {
         unsigned long last_power_on;
         unsigned long last_backlight_off;
         bool use_tps3;
+        bool can_mst; /* this port supports mst */
+        bool is_mst;
+        int active_mst_links;
+        /* connector directly attached - won't be use for modeset in mst world */
         struct intel_connector *attached_connector;
 
+        /* mst connector list */
+        struct intel_dp_mst_encoder *mst_encoders[I915_MAX_PIPES];
+        struct drm_dp_mst_topology_mgr mst_mgr;
+
         uint32_t (*get_aux_clock_divider)(struct intel_dp *dp, int index);
         /*
          * This function returns the value we have to program the AUX_CTL
@@ -573,6 +590,13 @@ struct intel_digital_port {
         bool (*hpd_pulse)(struct intel_digital_port *, bool);
 };
 
+struct intel_dp_mst_encoder {
+        struct intel_encoder base;
+        enum pipe pipe;
+        struct intel_digital_port *primary;
+        void *port; /* store this opaque as its illegal to dereference it */
+};
+
 static inline int
 vlv_dport_to_channel(struct intel_digital_port *dport)
 {
@@ -657,6 +681,12 @@ enc_to_dig_port(struct drm_encoder *encoder)
         return container_of(encoder, struct intel_digital_port, base.base);
 }
 
+static inline struct intel_dp_mst_encoder *
+enc_to_mst(struct drm_encoder *encoder)
+{
+        return container_of(encoder, struct intel_dp_mst_encoder, base.base);
+}
+
 static inline struct intel_dp *enc_to_intel_dp(struct drm_encoder *encoder)
 {
         return &enc_to_dig_port(encoder)->dp;
@@ -719,6 +749,9 @@ void intel_ddi_get_config(struct intel_encoder *encoder,
                           struct intel_crtc_config *pipe_config);
 
 void intel_ddi_init_dp_buf_reg(struct intel_encoder *encoder);
+void intel_ddi_clock_get(struct intel_encoder *encoder,
+                         struct intel_crtc_config *pipe_config);
+void intel_ddi_set_vc_payload_alloc(struct drm_crtc *crtc, bool state);
 
 /* intel_display.c */
 const char *intel_output_name(int output);
@@ -871,6 +904,15 @@ void intel_dp_set_drrs_state(struct drm_device *dev, int refresh_rate);
 void intel_edp_psr_exit(struct drm_device *dev);
 void intel_edp_psr_init(struct drm_device *dev);
 
+int intel_dp_handle_hpd_irq(struct intel_digital_port *digport, bool long_hpd);
+void intel_dp_add_properties(struct intel_dp *intel_dp, struct drm_connector *connector);
+void intel_dp_mst_suspend(struct drm_device *dev);
+void intel_dp_mst_resume(struct drm_device *dev);
+int intel_dp_max_link_bw(struct intel_dp *intel_dp);
+void intel_dp_hot_plug(struct intel_encoder *intel_encoder);
+/* 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);
 /* intel_dsi.c */
 void intel_dsi_init(struct drm_device *dev);
 
diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
index f475414671d8..7cdb8861bb7c 100644
--- a/drivers/gpu/drm/i915/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/intel_fbdev.c
@@ -375,6 +375,11 @@ static bool intel_fb_initial_config(struct drm_fb_helper *fb_helper,
                 }
 
                 encoder = connector->encoder;
+                if (!encoder) {
+                        struct drm_connector_helper_funcs *connector_funcs;
+                        connector_funcs = connector->helper_private;
+                        encoder = connector_funcs->best_encoder(connector);
+                }
                 if (!encoder || WARN_ON(!encoder->crtc)) {
                         DRM_DEBUG_KMS("connector %s has no encoder or crtc, skipping\n",
                                       connector->name);
diff --git a/drivers/gpu/drm/i915/intel_opregion.c b/drivers/gpu/drm/i915/intel_opregion.c
index 2e2c71fcc9ed..d37934b6338e 100644
--- a/drivers/gpu/drm/i915/intel_opregion.c
+++ b/drivers/gpu/drm/i915/intel_opregion.c
@@ -352,6 +352,7 @@ int intel_opregion_notify_encoder(struct intel_encoder *intel_encoder,
         case INTEL_OUTPUT_UNKNOWN:
         case INTEL_OUTPUT_DISPLAYPORT:
         case INTEL_OUTPUT_HDMI:
+        case INTEL_OUTPUT_DP_MST:
                 type = DISPLAY_TYPE_EXTERNAL_FLAT_PANEL;
                 break;
         case INTEL_OUTPUT_EDP: