2 files changed, 50 insertions, 5 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_dp.c b/drivers/gpu/drm/nouveau/nouveau_dp.c
index ad852e572cfe..59be357b17e0 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dp.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dp.c
@@ -36,12 +36,21 @@ MODULE_PARM_DESC(mst, "Enable DisplayPort multi-stream (default: enabled)");
 static int nouveau_mst = 1;
 module_param_named(mst, nouveau_mst, int, 0400);
 
+static bool
+nouveau_dp_has_sink_count(struct drm_connector *connector,
+			  struct nouveau_encoder *outp)
+{
+	return drm_dp_read_sink_count_cap(connector, outp->dp.dpcd, &outp->dp.desc);
+}
+
 static enum drm_connector_status
 nouveau_dp_probe_dpcd(struct nouveau_connector *nv_connector,
 		      struct nouveau_encoder *outp)
 {
+	struct drm_connector *connector = &nv_connector->base;
 	struct drm_dp_aux *aux = &nv_connector->aux;
 	struct nv50_mstm *mstm = NULL;
+	enum drm_connector_status status = connector_status_disconnected;
 	int ret;
 	u8 *dpcd = outp->dp.dpcd;
 
@@ -50,9 +59,9 @@ nouveau_dp_probe_dpcd(struct nouveau_connector *nv_connector,
 		ret = drm_dp_read_desc(aux, &outp->dp.desc,
 				       drm_dp_is_branch(dpcd));
 		if (ret < 0)
-			return connector_status_disconnected;
+			goto out;
 	} else {
-		return connector_status_disconnected;
+		goto out;
 	}
 
 	if (nouveau_mst) {
@@ -61,12 +70,33 @@ nouveau_dp_probe_dpcd(struct nouveau_connector *nv_connector,
 			mstm->can_mst = drm_dp_read_mst_cap(aux, dpcd);
 	}
 
+	if (nouveau_dp_has_sink_count(connector, outp)) {
+		ret = drm_dp_read_sink_count(aux);
+		if (ret < 0)
+			goto out;
+
+		outp->dp.sink_count = ret;
+
+		/*
+		 * Dongle connected, but no display. Don't bother reading
+		 * downstream port info
+		 */
+		if (!outp->dp.sink_count)
+			return connector_status_disconnected;
+	}
+
 	ret = drm_dp_read_downstream_info(aux, dpcd,
 					  outp->dp.downstream_ports);
 	if (ret < 0)
-		return connector_status_disconnected;
+		goto out;
 
-	return connector_status_connected;
+	status = connector_status_connected;
+out:
+	if (status != connector_status_connected) {
+		/* Clear any cached info */
+		outp->dp.sink_count = 0;
+	}
+	return status;
 }
 
 int
@@ -159,6 +189,8 @@ void nouveau_dp_irq(struct nouveau_drm *drm,
 	struct drm_connector *connector = &nv_connector->base;
 	struct nouveau_encoder *outp = find_encoder(connector, DCB_OUTPUT_DP);
 	struct nv50_mstm *mstm;
+	int ret;
+	bool send_hpd = false;
 
 	if (!outp)
 		return;
@@ -170,12 +202,23 @@ void nouveau_dp_irq(struct nouveau_drm *drm,
 
 	if (mstm && mstm->is_mst) {
 		if (!nv50_mstm_service(drm, nv_connector, mstm))
-			nouveau_connector_hpd(connector);
+			send_hpd = true;
 	} else {
 		drm_dp_cec_irq(&nv_connector->aux);
+
+		if (nouveau_dp_has_sink_count(connector, outp)) {
+			ret = drm_dp_read_sink_count(&nv_connector->aux);
+			if (ret != outp->dp.sink_count)
+				send_hpd = true;
+			if (ret >= 0)
+				outp->dp.sink_count = ret;
+		}
 	}
 
 	mutex_unlock(&outp->dp.hpd_irq_lock);
+
+	if (send_hpd)
+		nouveau_connector_hpd(connector);
 }
 
 /* TODO:
diff --git a/drivers/gpu/drm/nouveau/nouveau_encoder.h b/drivers/gpu/drm/nouveau/nouveau_encoder.h
index c1924a4529a7..21937f1c7dd9 100644
--- a/drivers/gpu/drm/nouveau/nouveau_encoder.h
+++ b/drivers/gpu/drm/nouveau/nouveau_encoder.h
@@ -74,6 +74,8 @@ struct nouveau_encoder {
 			u8 dpcd[DP_RECEIVER_CAP_SIZE];
 			u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS];
 			struct drm_dp_desc desc;
+
+			u8 sink_count;
 		} dp;
 	};