If the sink supports 128b/132b and single-stream sideband messaging, enable MST mode. With this, the topology manager will still write DP_MSTM_CTRL, which should be ignored by the sink. In the future, drm_dp_mst_topology_mgr_set_mst() bool mst_state parameter should probably be turned into an enum drm_dp_mst_mode mst_mode parameter. Cc: Arun R Murthy <arun.r.murthy@xxxxxxxxx> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx> --- drivers/gpu/drm/i915/display/intel_dp.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c index 4dd9c50226d1..16130e87dc23 100644 --- a/drivers/gpu/drm/i915/display/intel_dp.c +++ b/drivers/gpu/drm/i915/display/intel_dp.c @@ -4020,7 +4020,9 @@ static bool intel_dp_mst_detect(struct intel_dp *intel_dp) intel_dp->is_mst = i915->display.params.enable_dp_mst && intel_dp_mst_source_support(intel_dp) && - sink_mst_mode == DP_MST_CAPABLE; + (sink_mst_mode == DP_MST_CAPABLE || + (sink_mst_mode == DP_MST_SIDEBAND_MSG && + intel_dp->dpcd[DP_MAIN_LINK_CHANNEL_CODING] & DP_CAP_ANSI_128B132B)); drm_dbg_kms(&i915->drm, "[ENCODER:%d:%s] MST support: port: %s, sink: %s, modparam: %s -> enable: %s\n", -- 2.39.2
