6.6-stable review patch. If anyone has any objections, please let me know.
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From: Wayne Lin Wayne.Lin@amd.com
commit 3c6a743c6961cc2cab453b343bb157d6bbbf8120 upstream.
[Why] drm_dp_mst_topology_queue_probe() is used under the assumption that mst is already initialized. If we connect system with SST first then switch to the mst branch during suspend, we will fail probing topology by calling the wrong API since the mst manager is yet to be initialized.
[How] At dm_resume(), once it's detected as mst branc connected, check if the mst is initialized already. If not, call dm_helpers_dp_mst_start_top_mgr() instead to initialize mst
V2: Adjust the commit msg a bit
Fixes: bc068194f548 ("drm/amd/display: Don't write DP_MSTM_CTRL after LT") Cc: Fangzhi Zuo jerry.zuo@amd.com Cc: Mario Limonciello mario.limonciello@amd.com Cc: Alex Deucher alexander.deucher@amd.com Reviewed-by: Tom Chung chiahsuan.chung@amd.com Signed-off-by: Wayne Lin Wayne.Lin@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com (cherry picked from commit 62320fb8d91a0bddc44a228203cfa9bfbb5395bd) Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -2993,6 +2993,7 @@ static int dm_resume(void *handle) /* Do mst topology probing after resuming cached state*/ drm_connector_list_iter_begin(ddev, &iter); drm_for_each_connector_iter(connector, &iter) { + bool init = false;
if (connector->connector_type == DRM_MODE_CONNECTOR_WRITEBACK) continue; @@ -3002,7 +3003,14 @@ static int dm_resume(void *handle) aconnector->mst_root) continue;
- drm_dp_mst_topology_queue_probe(&aconnector->mst_mgr); + scoped_guard(mutex, &aconnector->mst_mgr.lock) { + init = !aconnector->mst_mgr.mst_primary; + } + if (init) + dm_helpers_dp_mst_start_top_mgr(aconnector->dc_link->ctx, + aconnector->dc_link, false); + else + drm_dp_mst_topology_queue_probe(&aconnector->mst_mgr); } drm_connector_list_iter_end(&iter);