2 files changed, 22 insertions, 1 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_encoder.h b/drivers/gpu/drm/nouveau/nouveau_encoder.h
index bc4a24029ed1..9f28b94e479b 100644
--- a/drivers/gpu/drm/nouveau/nouveau_encoder.h
+++ b/drivers/gpu/drm/nouveau/nouveau_encoder.h
@@ -47,6 +47,7 @@ struct nouveau_encoder {
 
         union {
                 struct {
+                        int mc_unknown;
                         int dpcd_version;
                         int link_nr;
                         int link_bw;
diff --git a/drivers/gpu/drm/nouveau/nv50_sor.c b/drivers/gpu/drm/nouveau/nv50_sor.c
index c2fff543b06f..e31ba312c2ff 100644
--- a/drivers/gpu/drm/nouveau/nv50_sor.c
+++ b/drivers/gpu/drm/nouveau/nv50_sor.c
@@ -211,7 +211,7 @@ nv50_sor_mode_set(struct drm_encoder *encoder, struct drm_display_mode *mode,
                         mode_ctl = 0x0200;
                 break;
         case OUTPUT_DP:
-                mode_ctl |= 0x00050000;
+                mode_ctl |= (nv_encoder->dp.mc_unknown << 16);
                 if (nv_encoder->dcb->sorconf.link & 1)
                         mode_ctl |= 0x00000800;
                 else
@@ -274,6 +274,7 @@ static const struct drm_encoder_funcs nv50_sor_encoder_funcs = {
 int
 nv50_sor_create(struct drm_device *dev, struct dcb_entry *entry)
 {
+        struct drm_nouveau_private *dev_priv = dev->dev_private;
         struct nouveau_encoder *nv_encoder = NULL;
         struct drm_encoder *encoder;
         bool dum;
@@ -319,5 +320,24 @@ nv50_sor_create(struct drm_device *dev, struct dcb_entry *entry)
         encoder->possible_crtcs = entry->heads;
         encoder->possible_clones = 0;
 
+        if (nv_encoder->dcb->type == OUTPUT_DP) {
+                uint32_t mc, or = nv_encoder->or;
+
+                if (dev_priv->chipset < 0x90 ||
+                    dev_priv->chipset == 0x92 || dev_priv->chipset == 0xa0)
+                        mc = nv_rd32(dev, NV50_PDISPLAY_SOR_MODE_CTRL_C(or));
+                else
+                        mc = nv_rd32(dev, NV90_PDISPLAY_SOR_MODE_CTRL_C(or));
+
+                switch ((mc & 0x00000f00) >> 8) {
+                case 8:
+                case 9:
+                        nv_encoder->dp.mc_unknown = (mc & 0x000f0000) >> 16;
+                        break;
+                default:
+                        break;
+                }
+        }
+
         return 0;
 }