drm: Add an encoder and connector type enum for DPI.

Right now exynos is exposing DPI as a TMDS encoder and VGA connector,
which seems rather misleading.  This isn't just an internal detail,
since xrandr actually exposes "VGA" as the output name.  Define some
new enums so that vc4's DPI can have a more informative name.

I considered other names for the connector as well.  For VC4, the
Adafruit DPI kippah takes the 28 GPIO pins and routes them to a
standard-ish 40-pin FPC connector, but "40-pin FPC" doesn't uniquely
identify an ordering of pins (apparently some other orderings exist),
doesn't explain things as well for the user (who, if anything, knows
their product is a DPI kippah/panel combo), and actually doesn't have
to exist (one could connect the 28 GPIOs directly to something else).
Simply "DPI" seems like a good compromise name to distinguish from the
HDMI, DSI, and TV connectors .

Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_crtc.c

@@ -168,6 +168,7 @@ static struct drm_conn_prop_enum_list drm_connector_enum_list[] = {
 	{ DRM_MODE_CONNECTOR_eDP, "eDP" },
 	{ DRM_MODE_CONNECTOR_VIRTUAL, "Virtual" },
 	{ DRM_MODE_CONNECTOR_DSI, "DSI" },
+	{ DRM_MODE_CONNECTOR_DPI, "DPI" },
 };
 
 static const struct drm_prop_enum_list drm_encoder_enum_list[] = {
@@ -179,6 +180,7 @@ static const struct drm_prop_enum_list drm_encoder_enum_list[] = {
 	{ DRM_MODE_ENCODER_VIRTUAL, "Virtual" },
 	{ DRM_MODE_ENCODER_DSI, "DSI" },
 	{ DRM_MODE_ENCODER_DPMST, "DP MST" },
+	{ DRM_MODE_ENCODER_DPI, "DPI" },
 };
 
 static const struct drm_prop_enum_list drm_subpixel_enum_list[] = {

include/uapi/drm/drm_mode.h

@@ -202,6 +202,7 @@ struct drm_mode_get_plane_res {
 #define DRM_MODE_ENCODER_VIRTUAL 5
 #define DRM_MODE_ENCODER_DSI	6
 #define DRM_MODE_ENCODER_DPMST	7
+#define DRM_MODE_ENCODER_DPI	8
 
 struct drm_mode_get_encoder {
 	__u32 encoder_id;
@@ -241,6 +242,7 @@ struct drm_mode_get_encoder {
 #define DRM_MODE_CONNECTOR_eDP		14
 #define DRM_MODE_CONNECTOR_VIRTUAL      15
 #define DRM_MODE_CONNECTOR_DSI		16
+#define DRM_MODE_CONNECTOR_DPI		17
 
 struct drm_mode_get_connector {