drm/radeon/kms/atom: fix duallink on some early DCE3.2 cards

Certain revisions of the vbios on DCE3.2 cards have a bug
in the transmitter control table which prevents duallink from
being enabled properly on some cards.  The action switch statement
jumps to the wrong offset for the OUTPUT_ENABLE action.  The fix
is to use the ENABLE action rather than the OUTPUT_ENABLE action
on the affected cards.  In fixed version of the vbios, both
actions jump to the same offset, so the change should be safe.
Reported-and-tested-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_encoders.c

@@ -1431,7 +1431,11 @@ radeon_atom_encoder_dpms(struct drm_encoder *encoder, int mode)
 	if (is_dig) {
 		switch (mode) {
 		case DRM_MODE_DPMS_ON:
-			atombios_dig_transmitter_setup(encoder, ATOM_TRANSMITTER_ACTION_ENABLE_OUTPUT, 0, 0);
+			/* some early dce3.2 boards have a bug in their transmitter control table */
+			if ((rdev->family == CHIP_RV710) || (rdev->family == CHIP_RV730))
+				atombios_dig_transmitter_setup(encoder, ATOM_TRANSMITTER_ACTION_ENABLE, 0, 0);
+			else
+				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);