drm/radeon/kms: fix DP after DPMS cycle

The transmitter needs to be enabled before the link is trained.
Reported-By: NLars Doelle <lars.doelle@on-line.de>
Signed-off-by: NAlex Deucher <alexdeucher@gmail.com>
Cc: stable <stable@kernel.org>
Signed-off-by: NDave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_encoders.c

@@ -1072,6 +1072,8 @@ radeon_atom_encoder_dpms(struct drm_encoder *encoder, int mode)
 	if (is_dig) {
 		switch (mode) {
 		case DRM_MODE_DPMS_ON:
+			if (!ASIC_IS_DCE4(rdev))
+				atombios_dig_transmitter_setup(encoder, ATOM_TRANSMITTER_ACTION_ENABLE_OUTPUT, 0, 0);
 			if (atombios_get_encoder_mode(encoder) == ATOM_ENCODER_MODE_DP) {
 				struct drm_connector *connector = radeon_get_connector_for_encoder(encoder);
 
@@ -1079,8 +1081,6 @@ radeon_atom_encoder_dpms(struct drm_encoder *encoder, int mode)
 				if (ASIC_IS_DCE4(rdev))
 					atombios_dig_encoder_setup(encoder, ATOM_ENCODER_CMD_DP_VIDEO_ON);
 			}
-			if (!ASIC_IS_DCE4(rdev))
-				atombios_dig_transmitter_setup(encoder, ATOM_TRANSMITTER_ACTION_ENABLE_OUTPUT, 0, 0);
 			break;
 		case DRM_MODE_DPMS_STANDBY:
 		case DRM_MODE_DPMS_SUSPEND: