drm/amd/display: Disable common modes for LVDS

[Why]
Common modes are added to LVDS for compatibility in clone mode, but
not all panels support them.  Non-native modes were disabled in the past
but this caused problems because compositors didn't use scaling for non
native modes. Now non-native modes on LVDS will enable the scaler by
default.

[How]
Check the connector type.  If the connector is LVDS avoid adding common
modes.

Reviewed-by: Harry Wentland <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

Author: alexdeucher

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -8374,7 +8374,8 @@ static int amdgpu_dm_connector_get_modes(struct drm_connector *connector)
 				drm_add_modes_noedid(connector, 1920, 1080);
 	} else {
 		amdgpu_dm_connector_ddc_get_modes(connector, drm_edid);
-		if (encoder && connector->connector_type != DRM_MODE_CONNECTOR_eDP)
+		if (encoder && (connector->connector_type != DRM_MODE_CONNECTOR_eDP) &&
+		    (connector->connector_type != DRM_MODE_CONNECTOR_LVDS))
 			amdgpu_dm_connector_add_common_modes(encoder, connector);
 		amdgpu_dm_connector_add_freesync_modes(connector, drm_edid);
 	}