[0/3] Fix mst daisy chain light up issue after resume

Message

Lin, Wayne June 26, 2024, 8:48 a.m. UTC

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(-)