drm/radeon/kms/atom: set sane defaults in atombios_get_encoder_mode()

If there was no connector mapped to the encoder, atombios_get_encoder_mode()
returned 0 which is the id for DP. Return something sane instead based on
the encoder id. This avoids hitting the DP paths on non-DP encoders.

Signed-off-by: Alex Deucher <[e-mail]>
Cc: [e-mail]
Signed-off-by: Dave Airlie <[e-mail]>

drivers/gpu/drm/radeon/radeon_encoders.c

···
 int
 atombios_get_encoder_mode(struct drm_encoder *encoder)
 {
+	struct radeon_encoder *radeon_encoder = to_radeon_encoder(encoder);
 	struct drm_device *dev = encoder->dev;
 	struct radeon_device *rdev = dev->dev_private;
 	struct drm_connector *connector;
···
 	struct radeon_connector_atom_dig *dig_connector;
 
 	connector = radeon_get_connector_for_encoder(encoder);
-	if (!connector)
-		return 0;
-
+	if (!connector) {
+		switch (radeon_encoder->encoder_id) {
+		case ENCODER_OBJECT_ID_INTERNAL_UNIPHY:
+		case ENCODER_OBJECT_ID_INTERNAL_UNIPHY1:
+		case ENCODER_OBJECT_ID_INTERNAL_UNIPHY2:
+		case ENCODER_OBJECT_ID_INTERNAL_KLDSCP_LVTMA:
+		case ENCODER_OBJECT_ID_INTERNAL_KLDSCP_DVO1:
+			return ATOM_ENCODER_MODE_DVI;
+		case ENCODER_OBJECT_ID_INTERNAL_KLDSCP_DAC1:
+		case ENCODER_OBJECT_ID_INTERNAL_KLDSCP_DAC2:
+		default:
+			return ATOM_ENCODER_MODE_CRT;
+		}
+	}
 	radeon_connector = to_radeon_connector(connector);
 
 	switch (connector->connector_type) {