Under DP mst daisy chain configuration, unplug one chained monitor during suspend and then resume, observe left connected monitor not light up. After analyzing, seems it's due to changing dpcd DP_MSTM_CTRL value after LT during reume. We used to defer handling UP request by disabling DP_UP_REQ_EN at the begining of resume process to avoid some problems. However, it turns out that it will cause problem on the hub if we change DP_UP_REQ_EN after LT. This series is trying to solve the problem by another way that we don't explicitly disable DP_UP_REQ_EN at source side. Instead, source should ignore the CSN event before source completeting topology probing during resume. Wayne Lin (3): drm/dp_mst: Fix all mstb marked as not probed after suspend/resume drm/dp_mst: Skip CSN if topology probing is not done yet drm/amd/display: Solve mst monitors blank out problem after resume drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 3 ++- drivers/gpu/drm/display/drm_dp_mst_topology.c | 15 +++++++++++++-- 2 files changed, 15 insertions(+), 3 deletions(-) -- 2.37.3
