drm/nouveau/kms: handle mDP connectors

commit d1f5a3f upstream.

In some cases we have the handle those explicitly as the fallback
connector type detection fails and marks those as eDP connectors.

Attempting to use such a connector with mutter leads to a crash of mutter
as it ends up with two eDP displays.

Information is taken from the official DCB documentation.

Cc: stable@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: Ben Skeggs <bskeggs@redhat.com>
Reported-by: Mark Pearson <markpearson@lenovo.com>
Tested-by: Mark Pearson <markpearson@lenovo.com>
Signed-off-by: Karol Herbst <kherbst@redhat.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gpu/drm/nouveau/include/nvkm/subdev/bios/conn.h

@@ -14,6 +14,7 @@ enum dcb_connector_type {
 	DCB_CONNECTOR_LVDS_SPWG = 0x41,
 	DCB_CONNECTOR_DP = 0x46,
 	DCB_CONNECTOR_eDP = 0x47,
+	DCB_CONNECTOR_mDP = 0x48,
 	DCB_CONNECTOR_HDMI_0 = 0x60,
 	DCB_CONNECTOR_HDMI_1 = 0x61,
 	DCB_CONNECTOR_HDMI_C = 0x63,

drivers/gpu/drm/nouveau/nouveau_connector.c

@@ -1210,6 +1210,7 @@ drm_conntype_from_dcb(enum dcb_connector_type dcb)
 	case DCB_CONNECTOR_DMS59_DP0:
 	case DCB_CONNECTOR_DMS59_DP1:
 	case DCB_CONNECTOR_DP       :
+	case DCB_CONNECTOR_mDP      :
 	case DCB_CONNECTOR_USB_C    : return DRM_MODE_CONNECTOR_DisplayPort;
 	case DCB_CONNECTOR_eDP      : return DRM_MODE_CONNECTOR_eDP;
 	case DCB_CONNECTOR_HDMI_0   :