From: Eric Yang Date: Tue, 12 Jun 2018 18:37:12 -0400 Subject: drm/amd/display: support access ddc for mst branch Git-commit: 0a14544661fad1606cc96aece30b2950fd9c4c81 Patch-mainline: v4.19-rc1 References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166 [Why] Megachip dockings accesses ddc line through display driver when installing FW. Previously, we would fail every transaction because link attached to mst branch did not have their ddc transaction type set. [How] Set ddc transaction type when mst branch is connected. Signed-off-by: Eric Yang Reviewed-by: Charlene Liu Acked-by: Harry Wentland Signed-off-by: Alex Deucher Acked-by: Petr Tesarik --- drivers/gpu/drm/amd/display/dc/core/dc_link.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c @@ -498,6 +498,10 @@ static bool detect_dp( sink_caps->signal = SIGNAL_TYPE_DISPLAY_PORT_MST; link->type = dc_connection_mst_branch; + dal_ddc_service_set_transaction_type( + link->ddc, + sink_caps->transaction_type); + /* * This call will initiate MST topology discovery. Which * will detect MST ports and add new DRM connector DRM