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, the topology manager should probably only set the sideband messaging related parts of the register. 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 | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c index 7f97d5512a3e..689d5c8ba6b0 100644 --- a/drivers/gpu/drm/i915/display/intel_dp.c +++ b/drivers/gpu/drm/i915/display/intel_dp.c @@ -4027,7 +4027,8 @@ intel_dp_mst_mode_choose(struct intel_dp *intel_dp, if (!intel_dp_mst_source_support(intel_dp)) return DRM_DP_SST; - if (sink_mst_mode == DRM_DP_SST_SIDEBAND_MSG) + if (sink_mst_mode == DRM_DP_SST_SIDEBAND_MSG && + !(intel_dp->dpcd[DP_MAIN_LINK_CHANNEL_CODING] & DP_CAP_ANSI_128B132B)) return DRM_DP_SST; return sink_mst_mode; -- 2.39.2
